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ActiveRecord::Base

Active Record

Active Record objects don’t specify their attributes directly, but rather infer them from the table definition with which they’re linked. Adding, removing, and changing attributes and their type is done directly in the database. Any change is instantly reflected in the Active Record objects. The mapping that binds a given Active Record class to a certain database table will happen automatically in most common cases, but can be overwritten for the uncommon ones.

See the mapping rules in table_name and the full example in files/activerecord/README_rdoc.html for more insight.

Creation

Active Records accept constructor parameters either in a hash or as a block. The hash method is especially useful when you’re receiving the data from somewhere else, like an HTTP request. It works like this:

  user = User.new(:name => "David", :occupation => "Code Artist")
  user.name # => "David"

You can also use block initialization:

  user = User.new do |u|
    u.name = "David"
    u.occupation = "Code Artist"
  end

And of course you can just create a bare object and specify the attributes after the fact:

  user = User.new
  user.name = "David"
  user.occupation = "Code Artist"

Conditions

Conditions can either be specified as a string, array, or hash representing the WHERE-part of an SQL statement. The array form is to be used when the condition input is tainted and requires sanitization. The string form can be used for statements that don’t involve tainted data. The hash form works much like the array form, except only equality and range is possible. Examples:

  class User < ActiveRecord::Base
    def self.authenticate_unsafely(user_name, password)
      where("user_name = '#{user_name}' AND password = '#{password}'").first
    end

    def self.authenticate_safely(user_name, password)
      where("user_name = ? AND password = ?", user_name, password).first
    end

    def self.authenticate_safely_simply(user_name, password)
      where(:user_name => user_name, :password => password).first
    end
  end

The authenticate_unsafely method inserts the parameters directly into the query and is thus susceptible to SQL-injection attacks if the user_name and password parameters come directly from an HTTP request. The authenticate_safely and authenticate_safely_simply both will sanitize the user_name and password before inserting them in the query, which will ensure that an attacker can’t escape the query and fake the login (or worse).

When using multiple parameters in the conditions, it can easily become hard to read exactly what the fourth or fifth question mark is supposed to represent. In those cases, you can resort to named bind variables instead. That’s done by replacing the question marks with symbols and supplying a hash with values for the matching symbol keys:

  Company.where(
    "id = :id AND name = :name AND division = :division AND created_at > :accounting_date",
    { :id => 3, :name => "37signals", :division => "First", :accounting_date => '2005-01-01' }
  ).first

Similarly, a simple hash without a statement will generate conditions based on equality with the SQL AND operator. For instance:

  Student.where(:first_name => "Harvey", :status => 1)
  Student.where(params[:student])

A range may be used in the hash to use the SQL BETWEEN operator:

  Student.where(:grade => 9..12)

An array may be used in the hash to use the SQL IN operator:

  Student.where(:grade => [9,11,12])

When joining tables, nested hashes or keys written in the form ‘table_name.column_name’ can be used to qualify the table name of a particular condition. For instance:

  Student.joins(:schools).where(:schools => { :type => 'public' })
  Student.joins(:schools).where('schools.type' => 'public' )

Overwriting default accessors

All column values are automatically available through basic accessors on the Active Record object, but sometimes you want to specialize this behavior. This can be done by overwriting the default accessors (using the same name as the attribute) and calling read_attribute(attr_name) and write_attribute(attr_name, value) to actually change things.

  class Song < ActiveRecord::Base
    # Uses an integer of seconds to hold the length of the song

    def length=(minutes)
      write_attribute(:length, minutes.to_i * 60)
    end

    def length
      read_attribute(:length) / 60
    end
  end

You can alternatively use self[:attribute]=(value) and self[:attribute] instead of write_attribute(:attribute, value) and read_attribute(:attribute).

Attribute query methods

In addition to the basic accessors, query methods are also automatically available on the Active Record object. Query methods allow you to test whether an attribute value is present.

For example, an Active Record User with the name attribute has a name? method that you can call to determine whether the user has a name:

  user = User.new(:name => "David")
  user.name? # => true

  anonymous = User.new(:name => "")
  anonymous.name? # => false

Accessing attributes before they have been typecasted

Sometimes you want to be able to read the raw attribute data without having the column-determined typecast run its course first. That can be done by using the <attribute>_before_type_cast accessors that all attributes have. For example, if your Account model has a balance attribute, you can call account.balance_before_type_cast or account.id_before_type_cast.

This is especially useful in validation situations where the user might supply a string for an integer field and you want to display the original string back in an error message. Accessing the attribute normally would typecast the string to 0, which isn’t what you want.

Dynamic attribute-based finders

Dynamic attribute-based finders are a cleaner way of getting (and/or creating) objects by simple queries without turning to SQL. They work by appending the name of an attribute to find_by_, find_last_by_, or find_all_by_ and thus produces finders like Person.find_by_user_name, Person.find_all_by_last_name, and Payment.find_by_transaction_id. Instead of writing Person.where(:user_name => user_name).first, you just do Person.find_by_user_name(user_name). And instead of writing Person.where(:last_name => last_name).all, you just do Person.find_all_by_last_name(last_name).

It’s also possible to use multiple attributes in the same find by separating them with “and“.

 Person.where(:user_name => user_name, :password => password).first
 Person.find_by_user_name_and_password #with dynamic finder

 Person.where(:user_name => user_name, :password => password, :gender => 'male').first
 Payment.find_by_user_name_and_password_and_gender

It’s even possible to call these dynamic finder methods on relations and named scopes.

  Payment.order("created_on").find_all_by_amount(50)
  Payment.pending.find_last_by_amount(100)

The same dynamic finder style can be used to create the object if it doesn’t already exist. This dynamic finder is called with find_or_create_by_ and will return the object if it already exists and otherwise creates it, then returns it. Protected attributes won’t be set unless they are given in a block.

  # No 'Summer' tag exists
  Tag.find_or_create_by_name("Summer") # equal to Tag.create(:name => "Summer")

  # Now the 'Summer' tag does exist
  Tag.find_or_create_by_name("Summer") # equal to Tag.find_by_name("Summer")

  # Now 'Bob' exist and is an 'admin'
  User.find_or_create_by_name('Bob', :age => 40) { |u| u.admin = true }

Use the find_or_initialize_by_ finder if you want to return a new record without saving it first. Protected attributes won’t be set unless they are given in a block.

  # No 'Winter' tag exists
  winter = Tag.find_or_initialize_by_name("Winter")
  winter.persisted? # false

To find by a subset of the attributes to be used for instantiating a new object, pass a hash instead of a list of parameters.

  Tag.find_or_create_by_name(:name => "rails", :creator => current_user)

That will either find an existing tag named “rails”, or create a new one while setting the user that created it.

Just like find_by_*, you can also use scoped_by_* to retrieve data. The good thing about using this feature is that the very first time result is returned using method_missing technique but after that the method is declared on the class. Henceforth method_missing will not be hit.

 User.scoped_by_user_name('David')

Saving arrays, hashes, and other non-mappable objects in text columns

Active Record can serialize any object in text columns using YAML. To do so, you must specify this with a call to the class method serialize. This makes it possible to store arrays, hashes, and other non-mappable objects without doing any additional work.

  class User < ActiveRecord::Base
    serialize :preferences
  end

  user = User.create(:preferences => { "background" => "black", "display" => large })
  User.find(user.id).preferences # => { "background" => "black", "display" => large }

You can also specify a class option as the second parameter that’ll raise an exception if a serialized object is retrieved as a descendant of a class not in the hierarchy.

  class User < ActiveRecord::Base
    serialize :preferences, Hash
  end

  user = User.create(:preferences => %w( one two three ))
  User.find(user.id).preferences    # raises SerializationTypeMismatch

Single table inheritance

Active Record allows inheritance by storing the name of the class in a column that by default is named “type” (can be changed by overwriting Base.inheritance_column). This means that an inheritance looking like this:

  class Company < ActiveRecord::Base; end
  class Firm < Company; end
  class Client < Company; end
  class PriorityClient < Client; end

When you do Firm.create(:name => "37signals"), this record will be saved in the companies table with type = “Firm”. You can then fetch this row again using Company.where(:name => '37signals').first and it will return a Firm object.

If you don’t have a type column defined in your table, single-table inheritance won’t be triggered. In that case, it’ll work just like normal subclasses with no special magic for differentiating between them or reloading the right type with find.

Note, all the attributes for all the cases are kept in the same table. Read more: www.martinfowler.com/eaaCatalog/singleTableInheritance.html

Connection to multiple databases in different models

Connections are usually created through ActiveRecord::Base.establish_connection and retrieved by ActiveRecord::Base.connection. All classes inheriting from ActiveRecord::Base will use this connection. But you can also set a class-specific connection. For example, if Course is an ActiveRecord::Base, but resides in a different database, you can just say Course.establish_connection and Course and all of its subclasses will use this connection instead.

This feature is implemented by keeping a connection pool in ActiveRecord::Base that is a Hash indexed by the class. If a connection is requested, the retrieve_connection method will go up the class-hierarchy until a connection is found in the connection pool.

Exceptions

Note: The attributes listed are class-level attributes (accessible from both the class and instance level). So it’s possible to assign a logger to the class through Base.logger= which will then be used by all instances in the current object space.

Attributes

abstract_class[RW]

Set this to true if this is an abstract class (see abstract_class?).

Public Class Methods

===(object) click to toggle source

Overwrite the default class equality method to provide support for association proxies.

     # File lib/active_record/base.rb, line 813
813:       def ===(object)
814:         object.is_a?(self)
815:       end
abstract_class?() click to toggle source

Returns whether this class is an abstract class or not.

     # File lib/active_record/base.rb, line 831
831:       def abstract_class?
832:         defined?(@abstract_class) && @abstract_class == true
833:       end
arel_engine() click to toggle source
     # File lib/active_record/base.rb, line 853
853:       def arel_engine
854:         @arel_engine ||= begin
855:           if self == ActiveRecord::Base
856:             Arel::Table.engine
857:           else
858:             connection_handler.connection_pools[name] ? self : superclass.arel_engine
859:           end
860:         end
861:       end
arel_table() click to toggle source
     # File lib/active_record/base.rb, line 849
849:       def arel_table
850:         @arel_table ||= Arel::Table.new(table_name, arel_engine)
851:       end
attr_readonly(*attributes) click to toggle source

Attributes listed as readonly will be used to create a new record but update operations will ignore these fields.

     # File lib/active_record/base.rb, line 521
521:       def attr_readonly(*attributes)
522:         write_inheritable_attribute(:attr_readonly, Set.new(attributes.map { |a| a.to_s }) + (readonly_attributes || []))
523:       end
attribute_method?(attribute) click to toggle source
     # File lib/active_record/base.rb, line 751
751:       def attribute_method?(attribute)
752:         super || (table_exists? && column_names.include?(attribute.to_s.sub(/=$/, '')))
753:       end
base_class() click to toggle source

Returns the base AR subclass that this class descends from. If A extends AR::Base, A.base_class will return A. If B descends from A through some arbitrarily deep hierarchy, B.base_class will return A.

If B < A and C < B and if A is an abstract_class then both B.base_class and C.base_class would return B as the answer since A is an abstract_class.

     # File lib/active_record/base.rb, line 823
823:       def base_class
824:         class_of_active_record_descendant(self)
825:       end
colorize_logging(*args) click to toggle source
     # File lib/active_record/base.rb, line 432
432:       def colorize_logging(*args)
433:         ActiveSupport::Deprecation.warn "ActiveRecord::Base.colorize_logging and " <<
434:           "config.active_record.colorize_logging are deprecated. Please use " <<
435:           "Rails::LogSubscriber.colorize_logging or config.colorize_logging instead", caller
436:       end
column_names() click to toggle source

Returns an array of column names as strings.

     # File lib/active_record/base.rb, line 691
691:       def column_names
692:         @column_names ||= columns.map { |column| column.name }
693:       end
columns() click to toggle source

Returns an array of column objects for the table associated with this class.

     # File lib/active_record/base.rb, line 677
677:       def columns
678:         unless defined?(@columns) && @columns
679:           @columns = connection.columns(table_name, "#{name} Columns")
680:           @columns.each { |column| column.primary = column.name == primary_key }
681:         end
682:         @columns
683:       end
columns_hash() click to toggle source

Returns a hash of column objects for the table associated with this class.

     # File lib/active_record/base.rb, line 686
686:       def columns_hash
687:         @columns_hash ||= Hash[columns.map { |column| [column.name, column] }]
688:       end
configurations click to toggle source

Contains the database configuration - as is typically stored in config/database.yml - as a Hash.

For example, the following database.yml...

  development:
    adapter: sqlite3
    database: db/development.sqlite3

  production:
    adapter: sqlite3
    database: db/production.sqlite3

…would result in ActiveRecord::Base.configurations to look like this:

  {
     'development' => {
        'adapter'  => 'sqlite3',
        'database' => 'db/development.sqlite3'
     },
     'production' => {
        'adapter'  => 'sqlite3',
        'database' => 'db/production.sqlite3'
     }
  }
     # File lib/active_record/base.rb, line 358
358:     cattr_accessor :configurations, :instance_writer => false
connected?() click to toggle source

Returns true if Active Record is connected.

     # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 101
101:       def connected?
102:         connection_handler.connected?(self)
103:       end
connection() click to toggle source

Returns the connection currently associated with the class. This can also be used to “borrow” the connection to do database work unrelated to any of the specific Active Records.

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 88
88:       def connection
89:         retrieve_connection
90:       end
connection_handler click to toggle source

The connection handler

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 13
13:     class_attribute :connection_handler, :instance_writer => false
connection_pool() click to toggle source
    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 92
92:       def connection_pool
93:         connection_handler.retrieve_connection_pool(self)
94:       end
content_columns() click to toggle source

Returns an array of column objects where the primary id, all columns ending in “_id” or “_count”, and columns used for single table inheritance have been removed.

     # File lib/active_record/base.rb, line 697
697:       def content_columns
698:         @content_columns ||= columns.reject { |c| c.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column }
699:       end
count_by_sql(sql) click to toggle source

Returns the result of an SQL statement that should only include a COUNT(*) in the SELECT part. The use of this method should be restricted to complicated SQL queries that can’t be executed using the ActiveRecord::Calculations class methods. Look into those before using this.

Parameters

  • sql - An SQL statement which should return a count query from the database, see the example below.

Examples

  Product.count_by_sql "SELECT COUNT(*) FROM sales s, customers c WHERE s.customer_id = c.id"
     # File lib/active_record/base.rb, line 514
514:       def count_by_sql(sql)
515:         sql = sanitize_conditions(sql)
516:         connection.select_value(sql, "#{name} Count").to_i
517:       end
create(attributes = nil, &block) click to toggle source

Creates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not.

The attributes parameter can be either be a Hash or an Array of Hashes. These Hashes describe the attributes on the objects that are to be created.

Examples

  # Create a single new object
  User.create(:first_name => 'Jamie')

  # Create an Array of new objects
  User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }])

  # Create a single object and pass it into a block to set other attributes.
  User.create(:first_name => 'Jamie') do |u|
    u.is_admin = false
  end

  # Creating an Array of new objects using a block, where the block is executed for each object:
  User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }]) do |u|
    u.is_admin = false
  end
     # File lib/active_record/base.rb, line 492
492:       def create(attributes = nil, &block)
493:         if attributes.is_a?(Array)
494:           attributes.collect { |attr| create(attr, &block) }
495:         else
496:           object = new(attributes)
497:           yield(object) if block_given?
498:           object.save
499:           object
500:         end
501:       end
default_timezone click to toggle source

Determines whether to use Time.local (using :local) or Time.utc (using :utc) when pulling dates and times from the database. This is set to :local by default.

     # File lib/active_record/base.rb, line 403
403:     cattr_accessor :default_timezone, :instance_writer => false
descends_from_active_record?() click to toggle source

True if this isn’t a concrete subclass needing a STI type condition.

     # File lib/active_record/base.rb, line 776
776:       def descends_from_active_record?
777:         if superclass.abstract_class?
778:           superclass.descends_from_active_record?
779:         else
780:           superclass == Base || !columns_hash.include?(inheritance_column)
781:         end
782:       end
establish_connection(spec = nil) click to toggle source

Establishes the connection to the database. Accepts a hash as input where the :adapter key must be specified with the name of a database adapter (in lower-case) example for regular databases (MySQL, Postgresql, etc):

  ActiveRecord::Base.establish_connection(
    :adapter  => "mysql",
    :host     => "localhost",
    :username => "myuser",
    :password => "mypass",
    :database => "somedatabase"
  )

Example for SQLite database:

  ActiveRecord::Base.establish_connection(
    :adapter => "sqlite",
    :database  => "path/to/dbfile"
  )

Also accepts keys as strings (for parsing from YAML for example):

  ActiveRecord::Base.establish_connection(
    "adapter" => "sqlite",
    "database"  => "path/to/dbfile"
  )

The exceptions AdapterNotSpecified, AdapterNotFound and ArgumentError may be returned on an error.

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 51
51:     def self.establish_connection(spec = nil)
52:       case spec
53:         when nil
54:           raise AdapterNotSpecified unless defined?(Rails.env)
55:           establish_connection(Rails.env)
56:         when ConnectionSpecification
57:           self.connection_handler.establish_connection(name, spec)
58:         when Symbol, String
59:           if configuration = configurations[spec.to_s]
60:             establish_connection(configuration)
61:           else
62:             raise AdapterNotSpecified, "#{spec} database is not configured"
63:           end
64:         else
65:           spec = spec.symbolize_keys
66:           unless spec.key?(:adapter) then raise AdapterNotSpecified, "database configuration does not specify adapter" end
67: 
68:           begin
69:             require "active_record/connection_adapters/#{spec[:adapter]}_adapter"
70:           rescue LoadError => e
71:             raise "Please install the #{spec[:adapter]} adapter: `gem install activerecord-#{spec[:adapter]}-adapter` (#{e})"
72:           end
73: 
74:           adapter_method = "#{spec[:adapter]}_connection"
75:           if !respond_to?(adapter_method)
76:             raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter"
77:           end
78: 
79:           remove_connection
80:           establish_connection(ConnectionSpecification.new(spec, adapter_method))
81:       end
82:     end
find_by_sql(sql) click to toggle source

Executes a custom SQL query against your database and returns all the results. The results will be returned as an array with columns requested encapsulated as attributes of the model you call this method from. If you call Product.find_by_sql then the results will be returned in a Product object with the attributes you specified in the SQL query.

If you call a complicated SQL query which spans multiple tables the columns specified by the SELECT will be attributes of the model, whether or not they are columns of the corresponding table.

The sql parameter is a full SQL query as a string. It will be called as is, there will be no database agnostic conversions performed. This should be a last resort because using, for example, MySQL specific terms will lock you to using that particular database engine or require you to change your call if you switch engines.

Examples

  # A simple SQL query spanning multiple tables
  Post.find_by_sql "SELECT p.title, c.author FROM posts p, comments c WHERE p.id = c.post_id"
  > [#<Post:0x36bff9c @attributes={"title"=>"Ruby Meetup", "first_name"=>"Quentin"}>, ...]

  # You can use the same string replacement techniques as you can with ActiveRecord#find
  Post.find_by_sql ["SELECT title FROM posts WHERE author = ? AND created > ?", author_id, start_date]
  > [#<Post:0x36bff9c @attributes={"first_name"=>"The Cheap Man Buys Twice"}>, ...]
     # File lib/active_record/base.rb, line 466
466:       def find_by_sql(sql)
467:         connection.select_all(sanitize_sql(sql), "#{name} Load").collect! { |record| instantiate(record) }
468:       end
inheritance_column() click to toggle source

Defines the column name for use with single table inheritance. Use set_inheritance_column to set a different value.

     # File lib/active_record/base.rb, line 610
610:       def inheritance_column
611:         @inheritance_column ||= "type"
612:       end
inspect() click to toggle source

Returns a string like ‘Post id:integer, title:string, body:text’

     # File lib/active_record/base.rb, line 790
790:       def inspect
791:         if self == Base
792:           super
793:         elsif abstract_class?
794:           "#{super}(abstract)"
795:         elsif table_exists?
796:           attr_list = columns.map { |c| "#{c.name}: #{c.type}" } * ', '
797:           "#{super}(#{attr_list})"
798:         else
799:           "#{super}(Table doesn't exist)"
800:         end
801:       end
logger click to toggle source

Accepts a logger conforming to the interface of Log4r or the default Ruby 1.8+ Logger class, which is then passed on to any new database connections made and which can be retrieved on both a class and instance level by calling logger.

     # File lib/active_record/base.rb, line 317
317:     cattr_accessor :logger, :instance_writer => false
new(attributes = nil) click to toggle source

New objects can be instantiated as either empty (pass no construction parameter) or pre-set with attributes but not yet saved (pass a hash with key names matching the associated table column names). In both instances, valid attribute keys are determined by the column names of the associated table — hence you can’t have attributes that aren’t part of the table columns.

      # File lib/active_record/base.rb, line 1393
1393:       def initialize(attributes = nil)
1394:         @attributes = attributes_from_column_definition
1395:         @attributes_cache = {}
1396:         @persisted = false
1397:         @readonly = false
1398:         @destroyed = false
1399:         @marked_for_destruction = false
1400:         @previously_changed = {}
1401:         @changed_attributes = {}
1402: 
1403:         ensure_proper_type
1404: 
1405:         populate_with_current_scope_attributes
1406:         self.attributes = attributes unless attributes.nil?
1407: 
1408:         result = yield self if block_given?
1409:         _run_initialize_callbacks
1410:         result
1411:       end
pluralize_table_names click to toggle source

Indicates whether table names should be the pluralized versions of the corresponding class names. If true, the default table name for a Product class will be products. If false, it would just be product. See table_name for the full rules on table/class naming. This is true, by default.

     # File lib/active_record/base.rb, line 396
396:     cattr_accessor :pluralize_table_names, :instance_writer => false
primary_key_prefix_type click to toggle source

Accessor for the prefix type that will be prepended to every primary key column name. The options are :table_name and :table_name_with_underscore. If the first is specified, the Product class will look for “productid” instead of “id” as the primary column. If the latter is specified, the Product class will look for “product_id“ instead of “id”. Remember that this is a global setting for all Active Records.

     # File lib/active_record/base.rb, line 368
368:     cattr_accessor :primary_key_prefix_type, :instance_writer => false
quoted_table_name() click to toggle source

Returns a quoted version of the table name, used to construct SQL statements.

     # File lib/active_record/base.rb, line 595
595:       def quoted_table_name
596:         @quoted_table_name ||= connection.quote_table_name(table_name)
597:       end
readonly_attributes() click to toggle source

Returns an array of all the attributes that have been specified as readonly.

     # File lib/active_record/base.rb, line 526
526:       def readonly_attributes
527:         read_inheritable_attribute(:attr_readonly) || []
528:       end
remove_connection(klass = self) click to toggle source
     # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 105
105:       def remove_connection(klass = self)
106:         connection_handler.remove_connection(klass)
107:       end
reset_column_information() click to toggle source

Resets all the cached information about columns, which will cause them to be reloaded on the next request.

The most common usage pattern for this method is probably in a migration, when just after creating a table you want to populate it with some default values, eg:

 class CreateJobLevels < ActiveRecord::Migration
   def self.up
     create_table :job_levels do |t|
       t.integer :id
       t.string :name

       t.timestamps
     end

     JobLevel.reset_column_information
     %w{assistant executive manager director}.each do |type|
       JobLevel.create(:name => type)
     end
   end

   def self.down
     drop_table :job_levels
   end
 end
     # File lib/active_record/base.rb, line 741
741:       def reset_column_information
742:         undefine_attribute_methods
743:         @column_names = @columns = @columns_hash = @content_columns = @dynamic_methods_hash = @inheritance_column = nil
744:         @arel_engine = @relation = @arel_table = nil
745:       end
respond_to?(method_id, include_private = false) click to toggle source
     # File lib/active_record/base.rb, line 835
835:       def respond_to?(method_id, include_private = false)
836:         if match = DynamicFinderMatch.match(method_id)
837:           return true if all_attributes_exists?(match.attribute_names)
838:         elsif match = DynamicScopeMatch.match(method_id)
839:           return true if all_attributes_exists?(match.attribute_names)
840:         end
841: 
842:         super
843:       end
retrieve_connection() click to toggle source
    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 96
96:       def retrieve_connection
97:         connection_handler.retrieve_connection(self)
98:       end
schema_format click to toggle source

Specifies the format to use when dumping the database schema with Rails’ Rakefile. If :sql, the schema is dumped as (potentially database- specific) SQL statements. If :ruby, the schema is dumped as an ActiveRecord::Schema file which can be loaded into any database that supports migrations. Use :ruby if you want to have different database adapters for, e.g., your development and test environments.

     # File lib/active_record/base.rb, line 414
414:     cattr_accessor :schema_format , :instance_writer => false
serialize(attr_name, class_name = Object) click to toggle source

If you have an attribute that needs to be saved to the database as an object, and retrieved as the same object, then specify the name of that attribute using this method and it will be handled automatically. The serialization is done through YAML. If class_name is specified, the serialized object must be of that class on retrieval or SerializationTypeMismatch will be raised.

Parameters

  • attr_name - The field name that should be serialized.

  • class_name - Optional, class name that the object type should be equal to.

Example

  # Serialize a preferences attribute
  class User
    serialize :preferences
  end
     # File lib/active_record/base.rb, line 545
545:       def serialize(attr_name, class_name = Object)
546:         serialized_attributes[attr_name.to_s] = class_name
547:       end
serialized_attributes() click to toggle source

Returns a hash of all the attributes that have been specified for serialization as keys and their class restriction as values.

     # File lib/active_record/base.rb, line 551
551:       def serialized_attributes
552:         read_inheritable_attribute(:attr_serialized) or write_inheritable_attribute(:attr_serialized, {})
553:       end
set_inheritance_column(value = nil, &block) click to toggle source

Sets the name of the inheritance column to use to the given value, or (if the value # is nil or false) to the value returned by the given block.

  class Project < ActiveRecord::Base
    set_inheritance_column do
      original_inheritance_column + "_id"
    end
  end
     # File lib/active_record/base.rb, line 647
647:       def set_inheritance_column(value = nil, &block)
648:         define_attr_method :inheritance_column, value, &block
649:       end
set_sequence_name(value = nil, &block) click to toggle source

Sets the name of the sequence to use when generating ids to the given value, or (if the value is nil or false) to the value returned by the given block. This is required for Oracle and is useful for any database which relies on sequences for primary key generation.

If a sequence name is not explicitly set when using Oracle or Firebird, it will default to the commonly used pattern of: #{table_name}_seq

If a sequence name is not explicitly set when using PostgreSQL, it will discover the sequence corresponding to your primary key for you.

  class Project < ActiveRecord::Base
    set_sequence_name "projectseq"   # default would have been "project_seq"
  end
     # File lib/active_record/base.rb, line 666
666:       def set_sequence_name(value = nil, &block)
667:         define_attr_method :sequence_name, value, &block
668:       end
set_table_name(value = nil, &block) click to toggle source

Sets the table name. If the value is nil or false then the value returned by the given block is used.

  class Project < ActiveRecord::Base
    set_table_name "project"
  end
     # File lib/active_record/base.rb, line 632
632:       def set_table_name(value = nil, &block)
633:         @quoted_table_name = nil
634:         define_attr_method :table_name, value, &block
635:       end
sti_name() click to toggle source
     # File lib/active_record/base.rb, line 845
845:       def sti_name
846:         store_full_sti_class ? name : name.demodulize
847:       end
subclasses() click to toggle source
     # File lib/active_record/base.rb, line 324
324:       def subclasses
325:         descendants
326:       end
table_exists?() click to toggle source

Indicates whether the table associated with this class exists

     # File lib/active_record/base.rb, line 672
672:       def table_exists?
673:         connection.table_exists?(table_name)
674:       end
table_name() click to toggle source

Guesses the table name (in forced lower-case) based on the name of the class in the inheritance hierarchy descending directly from ActiveRecord::Base. So if the hierarchy looks like: Reply < Message < ActiveRecord::Base, then Message is used to guess the table name even when called on Reply. The rules used to do the guess are handled by the Inflector class in Active Support, which knows almost all common English inflections. You can add new inflections in config/initializers/inflections.rb.

Nested classes are given table names prefixed by the singular form of the parent’s table name. Enclosing modules are not considered.

Examples

  class Invoice < ActiveRecord::Base; end;
  file                  class               table_name
  invoice.rb            Invoice             invoices

  class Invoice < ActiveRecord::Base; class Lineitem < ActiveRecord::Base; end; end;
  file                  class               table_name
  invoice.rb            Invoice::Lineitem   invoice_lineitems

  module Invoice; class Lineitem < ActiveRecord::Base; end; end;
  file                  class               table_name
  invoice/lineitem.rb   Invoice::Lineitem   lineitems

Additionally, the class-level table_name_prefix is prepended and the table_name_suffix is appended. So if you have “myapp_” as a prefix, the table name guess for an Invoice class becomes “myapp_invoices“. Invoice::Lineitem becomes “myapp_invoice_lineitems“.

You can also overwrite this class method to allow for unguessable links, such as a Mouse class with a link to a “mice” table. Example:

  class Mouse < ActiveRecord::Base
    set_table_name "mice"
  end
     # File lib/active_record/base.rb, line 590
590:       def table_name
591:         reset_table_name
592:       end
table_name_prefix click to toggle source

Accessor for the name of the prefix string to prepend to every table name. So if set to “basecamp_”, all table names will be named like “basecamp_projects“, “basecamp_people“, etc. This is a convenient way of creating a namespace for tables in a shared database. By default, the prefix is the empty string.

If you are organising your models within modules you can add a prefix to the models within a namespace by defining a singleton method in the parent module called table_name_prefix which returns your chosen prefix.

     # File lib/active_record/base.rb, line 381
381:     class_attribute :table_name_prefix, :instance_writer => false
table_name_suffix click to toggle source

Works like table_name_prefix, but appends instead of prepends (set to “_basecamp” gives “projects_basecamp“, “people_basecamp“). By default, the suffix is the empty string.

     # File lib/active_record/base.rb, line 388
388:     class_attribute :table_name_suffix, :instance_writer => false
timestamped_migrations click to toggle source

Specify whether or not to use timestamps for migration versions

     # File lib/active_record/base.rb, line 420
420:     cattr_accessor :timestamped_migrations , :instance_writer => false

Protected Class Methods

aggregate_mapping(reflection) click to toggle source
      # File lib/active_record/base.rb, line 1242
1242:         def aggregate_mapping(reflection)
1243:           mapping = reflection.options[:mapping] || [reflection.name, reflection.name]
1244:           mapping.first.is_a?(Array) ? mapping : [mapping]
1245:         end
class_of_active_record_descendant(klass) click to toggle source

Returns the class descending directly from ActiveRecord::Base or an abstract class, if any, in the inheritance hierarchy.

      # File lib/active_record/base.rb, line 1205
1205:         def class_of_active_record_descendant(klass)
1206:           if klass.superclass == Base || klass.superclass.abstract_class?
1207:             klass
1208:           elsif klass.superclass.nil?
1209:             raise ActiveRecordError, "#{name} doesn't belong in a hierarchy descending from ActiveRecord"
1210:           else
1211:             class_of_active_record_descendant(klass.superclass)
1212:           end
1213:         end
compute_type(type_name) click to toggle source

Returns the class type of the record using the current module as a prefix. So descendants of MyApp::Business::Account would appear as MyApp::Business::AccountSubclass.

      # File lib/active_record/base.rb, line 1177
1177:         def compute_type(type_name)
1178:           if type_name.match(/^::/)
1179:             # If the type is prefixed with a scope operator then we assume that
1180:             # the type_name is an absolute reference.
1181:             ActiveSupport::Dependencies.constantize(type_name)
1182:           else
1183:             # Build a list of candidates to search for
1184:             candidates = []
1185:             name.scan(/::|$/) { candidates.unshift "#{$`}::#{type_name}" }
1186:             candidates << type_name
1187: 
1188:             candidates.each do |candidate|
1189:               begin
1190:                 constant = ActiveSupport::Dependencies.constantize(candidate)
1191:                 return constant if candidate == constant.to_s
1192:               rescue NameError => e
1193:                 # We don't want to swallow NoMethodError < NameError errors
1194:                 raise e unless e.instance_of?(NameError)
1195:               rescue ArgumentError
1196:               end
1197:             end
1198: 
1199:             raise NameError, "uninitialized constant #{candidates.first}"
1200:           end
1201:         end
default_scope(options = {}) click to toggle source

Sets the default options for the model. The format of the options argument is the same as in find.

  class Person < ActiveRecord::Base
    default_scope order('last_name, first_name')
  end

default_scope is also applied while creating/building a record. It is not applied while updating a record.

  class Article < ActiveRecord::Base
    default_scope where(:published => true)
  end

  Article.new.published    # => true
  Article.create.published # => true
      # File lib/active_record/base.rb, line 1162
1162:         def default_scope(options = {})
1163:           reset_scoped_methods
1164:           self.default_scoping << construct_finder_arel(options, default_scoping.pop)
1165:         end
expand_hash_conditions_for_aggregates(attrs) click to toggle source

Accepts a hash of SQL conditions and replaces those attributes that correspond to a composed_of relationship with their expanded aggregate attribute values. Given:

    class Person < ActiveRecord::Base
      composed_of :address, :class_name => "Address",
        :mapping => [%w(address_street street), %w(address_city city)]
    end

Then:

    { :address => Address.new("813 abc st.", "chicago") }
      # => { :address_street => "813 abc st.", :address_city => "chicago" }
      # File lib/active_record/base.rb, line 1258
1258:         def expand_hash_conditions_for_aggregates(attrs)
1259:           expanded_attrs = {}
1260:           attrs.each do |attr, value|
1261:             unless (aggregation = reflect_on_aggregation(attr.to_sym)).nil?
1262:               mapping = aggregate_mapping(aggregation)
1263:               mapping.each do |field_attr, aggregate_attr|
1264:                 if mapping.size == 1 && !value.respond_to?(aggregate_attr)
1265:                   expanded_attrs[field_attr] = value
1266:                 else
1267:                   expanded_attrs[field_attr] = value.send(aggregate_attr)
1268:                 end
1269:               end
1270:             else
1271:               expanded_attrs[attr] = value
1272:             end
1273:           end
1274:           expanded_attrs
1275:         end
sanitize_sql_array(ary) click to toggle source

Accepts an array of conditions. The array has each value sanitized and interpolated into the SQL statement.

  ["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
      # File lib/active_record/base.rb, line 1312
1312:         def sanitize_sql_array(ary)
1313:           statement, *values = ary
1314:           if values.first.is_a?(Hash) and statement =~ /:\w+/
1315:             replace_named_bind_variables(statement, values.first)
1316:           elsif statement.include?('?')
1317:             replace_bind_variables(statement, values)
1318:           elsif statement.blank?
1319:             statement
1320:           else
1321:             statement % values.collect { |value| connection.quote_string(value.to_s) }
1322:           end
1323:         end
sanitize_sql_for_assignment(assignments) click to toggle source

Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a SET clause.

  { :name => nil, :group_id => 4 }  returns "name = NULL , group_id='4'"
      # File lib/active_record/base.rb, line 1234
1234:         def sanitize_sql_for_assignment(assignments)
1235:           case assignments
1236:             when Array; sanitize_sql_array(assignments)
1237:             when Hash;  sanitize_sql_hash_for_assignment(assignments)
1238:             else        assignments
1239:           end
1240:         end
sanitize_sql_for_conditions(condition, table_name = self.table_name) click to toggle source

Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a WHERE clause.

  ["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
  { :name => "foo'bar", :group_id => 4 }  returns "name='foo''bar' and group_id='4'"
  "name='foo''bar' and group_id='4'" returns "name='foo''bar' and group_id='4'"
      # File lib/active_record/base.rb, line 1220
1220:         def sanitize_sql_for_conditions(condition, table_name = self.table_name)
1221:           return nil if condition.blank?
1222: 
1223:           case condition
1224:             when Array; sanitize_sql_array(condition)
1225:             when Hash;  sanitize_sql_hash_for_conditions(condition, table_name)
1226:             else        condition
1227:           end
1228:         end
sanitize_sql_hash_for_assignment(attrs) click to toggle source

Sanitizes a hash of attribute/value pairs into SQL conditions for a SET clause.

  { :status => nil, :group_id => 1 }
    # => "status = NULL , group_id = 1"
      # File lib/active_record/base.rb, line 1303
1303:         def sanitize_sql_hash_for_assignment(attrs)
1304:           attrs.map do |attr, value|
1305:             "#{connection.quote_column_name(attr)} = #{quote_bound_value(value)}"
1306:           end.join(', ')
1307:         end
sanitize_sql_hash_for_conditions(attrs, default_table_name = self.table_name) click to toggle source

Sanitizes a hash of attribute/value pairs into SQL conditions for a WHERE clause.

  { :name => "foo'bar", :group_id => 4 }
    # => "name='foo''bar' and group_id= 4"
  { :status => nil, :group_id => [1,2,3] }
    # => "status IS NULL and group_id IN (1,2,3)"
  { :age => 13..18 }
    # => "age BETWEEN 13 AND 18"
  { 'other_records.id' => 7 }
    # => "`other_records`.`id` = 7"
  { :other_records => { :id => 7 } }
    # => "`other_records`.`id` = 7"

And for value objects on a composed_of relationship:

  { :address => Address.new("123 abc st.", "chicago") }
    # => "address_street='123 abc st.' and address_city='chicago'"
      # File lib/active_record/base.rb, line 1291
1291:         def sanitize_sql_hash_for_conditions(attrs, default_table_name = self.table_name)
1292:           attrs = expand_hash_conditions_for_aggregates(attrs)
1293: 
1294:           table = Arel::Table.new(self.table_name, :engine => arel_engine, :as => default_table_name)
1295:           builder = PredicateBuilder.new(arel_engine)
1296:           builder.build_from_hash(attrs, table).map{ |b| b.to_sql }.join(' AND ')
1297:         end
with_exclusive_scope(method_scoping = {}, &block) click to toggle source

Works like with_scope, but discards any nested properties.

      # File lib/active_record/base.rb, line 1128
1128:         def with_exclusive_scope(method_scoping = {}, &block)
1129:           if method_scoping.values.any? { |e| e.is_a?(ActiveRecord::Relation) }
1130:             raise ArgumentError, New finder API can not be used with_exclusive_scope. You can either call unscoped to get an anonymous scope not bound to the default_scope:  User.unscoped.where(:active => true)Or call unscoped with a block:  User.unscoped do    User.where(:active => true).all  end
1131:           end
1132:           with_scope(method_scoping, :overwrite, &block)
1133:         end
with_scope(method_scoping = {}, action = :merge, &block) click to toggle source

with_scope lets you apply options to inner block incrementally. It takes a hash and the keys must be :find or :create. :find parameter is Relation while :create parameters are an attributes hash.

  class Article < ActiveRecord::Base
    def self.create_with_scope
      with_scope(:find => where(:blog_id => 1), :create => { :blog_id => 1 }) do
        find(1) # => SELECT * from articles WHERE blog_id = 1 AND id = 1
        a = create(1)
        a.blog_id # => 1
      end
    end
  end

In nested scopings, all previous parameters are overwritten by the innermost rule, with the exception of where, includes, and joins operations in Relation, which are merged.

joins operations are uniqued so multiple scopes can join in the same table without table aliasing problems. If you need to join multiple tables, but still want one of the tables to be uniqued, use the array of strings format for your joins.

  class Article < ActiveRecord::Base
    def self.find_with_scope
      with_scope(:find => where(:blog_id => 1).limit(1), :create => { :blog_id => 1 }) do
        with_scope(:find => limit(10)) do
          all # => SELECT * from articles WHERE blog_id = 1 LIMIT 10
        end
        with_scope(:find => where(:author_id => 3)) do
          all # => SELECT * from articles WHERE blog_id = 1 AND author_id = 3 LIMIT 1
        end
      end
    end
  end

You can ignore any previous scopings by using the with_exclusive_scope method.

  class Article < ActiveRecord::Base
    def self.find_with_exclusive_scope
      with_scope(:find => where(:blog_id => 1).limit(1)) do
        with_exclusive_scope(:find => limit(10)) do
          all # => SELECT * from articles LIMIT 10
        end
      end
    end
  end

Note: the :find scope also has effect on update and deletion methods, like update_all and delete_all.

      # File lib/active_record/base.rb, line 1087
1087:         def with_scope(method_scoping = {}, action = :merge, &block)
1088:           method_scoping = method_scoping.method_scoping if method_scoping.respond_to?(:method_scoping)
1089: 
1090:           if method_scoping.is_a?(Hash)
1091:             # Dup first and second level of hash (method and params).
1092:             method_scoping = method_scoping.dup
1093:             method_scoping.each do |method, params|
1094:               method_scoping[method] = params.dup unless params == true
1095:             end
1096: 
1097:             method_scoping.assert_valid_keys([ :find, :create ])
1098:             relation = construct_finder_arel(method_scoping[:find] || {})
1099: 
1100:             if current_scoped_methods && current_scoped_methods.create_with_value && method_scoping[:create]
1101:               scope_for_create = if action == :merge
1102:                 current_scoped_methods.create_with_value.merge(method_scoping[:create])
1103:               else
1104:                 method_scoping[:create]
1105:               end
1106: 
1107:               relation = relation.create_with(scope_for_create)
1108:             else
1109:               scope_for_create = method_scoping[:create]
1110:               scope_for_create ||= current_scoped_methods.create_with_value if current_scoped_methods
1111:               relation = relation.create_with(scope_for_create) if scope_for_create
1112:             end
1113: 
1114:             method_scoping = relation
1115:           end
1116: 
1117:           method_scoping = current_scoped_methods.merge(method_scoping) if current_scoped_methods && action ==  :merge
1118: 
1119:           self.scoped_methods << method_scoping
1120:           begin
1121:             yield
1122:           ensure
1123:             self.scoped_methods.pop
1124:           end
1125:         end

Private Class Methods

all_attributes_exists?(attribute_names) click to toggle source
      # File lib/active_record/base.rb, line 1033
1033:         def all_attributes_exists?(attribute_names)
1034:           expand_attribute_names_for_aggregates(attribute_names).all? { |name|
1035:             column_methods_hash.include?(name.to_sym)
1036:           }
1037:         end
attributes_protected_by_default() click to toggle source

The primary key and inheritance column can never be set by mass-assignment for security reasons.

      # File lib/active_record/base.rb, line 1704
1704:       def self.attributes_protected_by_default
1705:         default = [ primary_key, inheritance_column ]
1706:         default << 'id' unless primary_key.eql? 'id'
1707:         default
1708:       end
compute_table_name() click to toggle source

Computes and returns a table name according to default conventions.

     # File lib/active_record/base.rb, line 955
955:         def compute_table_name
956:           base = base_class
957:           if self == base
958:             # Nested classes are prefixed with singular parent table name.
959:             if parent < ActiveRecord::Base && !parent.abstract_class?
960:               contained = parent.table_name
961:               contained = contained.singularize if parent.pluralize_table_names
962:               contained << '_'
963:             end
964:             "#{full_table_name_prefix}#{contained}#{undecorated_table_name(name)}#{table_name_suffix}"
965:           else
966:             # STI subclasses always use their superclass' table.
967:             base.table_name
968:           end
969:         end
construct_attributes_from_arguments(attribute_names, arguments) click to toggle source
      # File lib/active_record/base.rb, line 1012
1012:         def construct_attributes_from_arguments(attribute_names, arguments)
1013:           attributes = {}
1014:           attribute_names.each_with_index { |name, idx| attributes[name] = arguments[idx] }
1015:           attributes
1016:         end
construct_finder_arel(options = {}, scope = nil) click to toggle source
     # File lib/active_record/base.rb, line 933
933:         def construct_finder_arel(options = {}, scope = nil)
934:           relation = options.is_a?(Hash) ? unscoped.apply_finder_options(options) : options
935:           relation = scope.merge(relation) if scope
936:           relation
937:         end
expand_attribute_names_for_aggregates(attribute_names) click to toggle source

Similar in purpose to expand_hash_conditions_for_aggregates.

      # File lib/active_record/base.rb, line 1019
1019:         def expand_attribute_names_for_aggregates(attribute_names)
1020:           expanded_attribute_names = []
1021:           attribute_names.each do |attribute_name|
1022:             unless (aggregation = reflect_on_aggregation(attribute_name.to_sym)).nil?
1023:               aggregate_mapping(aggregation).each do |field_attr, aggregate_attr|
1024:                 expanded_attribute_names << field_attr
1025:               end
1026:             else
1027:               expanded_attribute_names << attribute_name
1028:             end
1029:           end
1030:           expanded_attribute_names
1031:         end
find_sti_class(type_name) click to toggle source
     # File lib/active_record/base.rb, line 913
913:         def find_sti_class(type_name)
914:           if type_name.blank? || !columns_hash.include?(inheritance_column)
915:             self
916:           else
917:             begin
918:               if store_full_sti_class
919:                 ActiveSupport::Dependencies.constantize(type_name)
920:               else
921:                 compute_type(type_name)
922:               end
923:             rescue NameError
924:               raise SubclassNotFound,
925:                 "The single-table inheritance mechanism failed to locate the subclass: '#{type_name}'. " +
926:                 "This error is raised because the column '#{inheritance_column}' is reserved for storing the class in case of inheritance. " +
927:                 "Please rename this column if you didn't intend it to be used for storing the inheritance class " +
928:                 "or overwrite #{name}.inheritance_column to use another column for that information."
929:             end
930:           end
931:         end
instantiate(record) click to toggle source

Finder methods must instantiate through this method to work with the single-table inheritance model that makes it possible to create objects of different types from the same table.

     # File lib/active_record/base.rb, line 907
907:         def instantiate(record)
908:           model = find_sti_class(record[inheritance_column]).allocate
909:           model.init_with('attributes' => record)
910:           model
911:         end
method_missing(method_id, *arguments, &block) click to toggle source

Enables dynamic finders like User.find_by_user_name(user_name) and User.scoped_by_user_name(user_name). Refer to Dynamic attribute-based finders section at the top of this file for more detailed information.

It’s even possible to use all the additional parameters to find. For example, the full interface for find_all_by_amount is actually find_all_by_amount(amount, options).

Each dynamic finder using scoped_by_* is also defined in the class after it is first invoked, so that future attempts to use it do not run through method_missing.

      # File lib/active_record/base.rb, line 980
 980:         def method_missing(method_id, *arguments, &block)
 981:           if match = DynamicFinderMatch.match(method_id)
 982:             attribute_names = match.attribute_names
 983:             super unless all_attributes_exists?(attribute_names)
 984:             if match.finder?
 985:               options = arguments.extract_options!
 986:               relation = options.any? ? construct_finder_arel(options, current_scoped_methods) : scoped
 987:               relation.send :find_by_attributes, match, attribute_names, *arguments
 988:             elsif match.instantiator?
 989:               scoped.send :find_or_instantiator_by_attributes, match, attribute_names, *arguments, &block
 990:             end
 991:           elsif match = DynamicScopeMatch.match(method_id)
 992:             attribute_names = match.attribute_names
 993:             super unless all_attributes_exists?(attribute_names)
 994:             if match.scope?
 995:               self.class_eval                 def self.#{method_id}(*args)                        # def self.scoped_by_user_name_and_password(*args)                  options = args.extract_options!                   #   options = args.extract_options!                  attributes = construct_attributes_from_arguments( #   attributes = construct_attributes_from_arguments(                    [:#{attribute_names.join(',:')}], args          #     [:user_name, :password], args                  )                                                 #   )                                                                    #                  scoped(:conditions => attributes)                 #   scoped(:conditions => attributes)                end                                                 # end, __FILE__, __LINE__ + 1
 996:               send(method_id, *arguments)
 997:             end
 998:           else
 999:             super
1000:           end
1001:         end
type_condition() click to toggle source
     # File lib/active_record/base.rb, line 939
939:         def type_condition
940:           sti_column = arel_table[inheritance_column]
941:           condition = sti_column.eq(sti_name)
942:           descendants.each { |subclass| condition = condition.or(sti_column.eq(subclass.sti_name)) }
943: 
944:           condition
945:         end
undecorated_table_name(class_name = base_class.name) click to toggle source

Guesses the table name, but does not decorate it with prefix and suffix information.

     # File lib/active_record/base.rb, line 948
948:         def undecorated_table_name(class_name = base_class.name)
949:           table_name = class_name.to_s.demodulize.underscore
950:           table_name = table_name.pluralize if pluralize_table_names
951:           table_name
952:         end

Public Instance Methods

==(comparison_object) click to toggle source

Returns true if comparison_object is the same exact object, or comparison_object is of the same type and self has an ID and it is equal to comparison_object.id.

Note that new records are different from any other record by definition, unless the other record is the receiver itself. Besides, if you fetch existing records with select and leave the ID out, you’re on your own, this predicate will return false.

Note also that destroying a record preserves its ID in the model instance, so deleted models are still comparable.

      # File lib/active_record/base.rb, line 1619
1619:       def ==(comparison_object)
1620:         comparison_object.equal?(self) ||
1621:           comparison_object.instance_of?(self.class) &&
1622:           id.present? &&
1623:           comparison_object.id == id
1624:       end
[](attr_name) click to toggle source

Returns the value of the attribute identified by attr_name after it has been typecast (for example, “2004-12-12” in a data column is cast to a date object, like Date.new(2004, 12, 12)). (Alias for the protected read_attribute method).

      # File lib/active_record/base.rb, line 1518
1518:       def [](attr_name)
1519:         read_attribute(attr_name)
1520:       end
[]=(attr_name, value) click to toggle source

Updates the attribute identified by attr_name with the specified value. (Alias for the protected write_attribute method).

      # File lib/active_record/base.rb, line 1524
1524:       def []=(attr_name, value)
1525:         write_attribute(attr_name, value)
1526:       end
attribute_for_inspect(attr_name) click to toggle source

Returns an #-like string for the value of the attribute attr_name. String attributes are elided after 50 characters, and Date and Time attributes are returned in the :db format. Other attributes return the value of # without modification.

  person = Person.create!(:name => "David Heinemeier Hansson " * 3)

  person.attribute_for_inspect(:name)
  # => '"David Heinemeier Hansson David Heinemeier Hansson D..."'

  person.attribute_for_inspect(:created_at)
  # => '"2009-01-12 04:48:57"'
      # File lib/active_record/base.rb, line 1586
1586:       def attribute_for_inspect(attr_name)
1587:         value = read_attribute(attr_name)
1588: 
1589:         if value.is_a?(String) && value.length > 50
1590:           "#{value[0..50]}...".inspect
1591:         elsif value.is_a?(Date) || value.is_a?(Time)
1592:           %("#{value.to_s(:db)}")
1593:         else
1594:           value.inspect
1595:         end
1596:       end
attribute_names() click to toggle source

Returns an array of names for the attributes available on this object sorted alphabetically.

      # File lib/active_record/base.rb, line 1511
1511:       def attribute_names
1512:         @attributes.keys.sort
1513:       end
attribute_present?(attribute) click to toggle source

Returns true if the specified attribute has been set by the user or by a database load and is neither nil nor empty? (the latter only applies to objects that respond to empty?, most notably Strings).

      # File lib/active_record/base.rb, line 1600
1600:       def attribute_present?(attribute)
1601:         value = read_attribute(attribute)
1602:         !value.blank?
1603:       end
attributes() click to toggle source

Returns a hash of all the attributes with their names as keys and the values of the attributes as values.

      # File lib/active_record/base.rb, line 1567
1567:       def attributes
1568:         attrs = {}
1569:         attribute_names.each { |name| attrs[name] = read_attribute(name) }
1570:         attrs
1571:       end
attributes=(new_attributes, guard_protected_attributes = true) click to toggle source

Allows you to set all the attributes at once by passing in a hash with keys matching the attribute names (which again matches the column names).

If guard_protected_attributes is true (the default), then sensitive attributes can be protected from this form of mass-assignment by using the attr_protected macro. Or you can alternatively specify which attributes can be accessed with the attr_accessible macro. Then all the attributes not included in that won’t be allowed to be mass-assigned.

  class User < ActiveRecord::Base
    attr_protected :is_admin
  end

  user = User.new
  user.attributes = { :username => 'Phusion', :is_admin => true }
  user.username   # => "Phusion"
  user.is_admin?  # => false

  user.send(:attributes=, { :username => 'Phusion', :is_admin => true }, false)
  user.is_admin?  # => true
      # File lib/active_record/base.rb, line 1548
1548:       def attributes=(new_attributes, guard_protected_attributes = true)
1549:         return unless new_attributes.is_a?(Hash)
1550:         attributes = new_attributes.stringify_keys
1551: 
1552:         multi_parameter_attributes = []
1553:         attributes = sanitize_for_mass_assignment(attributes) if guard_protected_attributes
1554: 
1555:         attributes.each do |k, v|
1556:           if k.include?("(")
1557:             multi_parameter_attributes << [ k, v ]
1558:           else
1559:             respond_to?(:"#{k}=") ? send(:"#{k}=", v) : raise(UnknownAttributeError, "unknown attribute: #{k}")
1560:           end
1561:         end
1562: 
1563:         assign_multiparameter_attributes(multi_parameter_attributes)
1564:       end
cache_key() click to toggle source

Returns a cache key that can be used to identify this record.

Examples

  Product.new.cache_key     # => "products/new"
  Product.find(5).cache_key # => "products/5" (updated_at not available)
  Person.find(5).cache_key  # => "people/5-20071224150000" (updated_at available)
      # File lib/active_record/base.rb, line 1490
1490:       def cache_key
1491:         case
1492:         when !persisted?
1493:           "#{self.class.model_name.cache_key}/new"
1494:         when timestamp = self[:updated_at]
1495:           "#{self.class.model_name.cache_key}/#{id}-#{timestamp.to_s(:number)}"
1496:         else
1497:           "#{self.class.model_name.cache_key}/#{id}"
1498:         end
1499:       end
column_for_attribute(name) click to toggle source

Returns the column object for the named attribute.

      # File lib/active_record/base.rb, line 1606
1606:       def column_for_attribute(name)
1607:         self.class.columns_hash[name.to_s]
1608:       end
connection() click to toggle source

Returns the connection currently associated with the class. This can also be used to “borrow” the connection to do database work that isn’t easily done without going straight to SQL.

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 19
19:     def connection
20:       self.class.connection
21:     end
dup() click to toggle source

Returns duplicated record with unfreezed attributes.

      # File lib/active_record/base.rb, line 1648
1648:       def dup
1649:         obj = super
1650:         obj.instance_variable_set('@attributes', @attributes.dup)
1651:         obj
1652:       end
eql?(comparison_object) click to toggle source

Delegates to ==

      # File lib/active_record/base.rb, line 1627
1627:       def eql?(comparison_object)
1628:         self == (comparison_object)
1629:       end
freeze() click to toggle source

Freeze the attributes hash such that associations are still accessible, even on destroyed records.

      # File lib/active_record/base.rb, line 1638
1638:       def freeze
1639:         @attributes.freeze; self
1640:       end
frozen?() click to toggle source

Returns true if the attributes hash has been frozen.

      # File lib/active_record/base.rb, line 1643
1643:       def frozen?
1644:         @attributes.frozen?
1645:       end
has_attribute?(attr_name) click to toggle source

Returns true if the given attribute is in the attributes hash

      # File lib/active_record/base.rb, line 1506
1506:       def has_attribute?(attr_name)
1507:         @attributes.has_key?(attr_name.to_s)
1508:       end
hash() click to toggle source

Delegates to id in order to allow two records of the same type and id to work with something like:

  [ Person.find(1), Person.find(2), Person.find(3) ] & [ Person.find(1), Person.find(4) ] # => [ Person.find(1) ]
      # File lib/active_record/base.rb, line 1633
1633:       def hash
1634:         id.hash
1635:       end
init_with(coder) click to toggle source

Initialize an empty model object from coder. coder must contain the attributes necessary for initializing an empty model object. For example:

  class Post < ActiveRecord::Base
  end

  post = Post.allocate
  post.init_with('attributes' => { 'title' => 'hello world' })
  post.title # => 'hello world'
      # File lib/active_record/base.rb, line 1447
1447:       def init_with(coder)
1448:         @attributes = coder['attributes']
1449:         @attributes_cache, @previously_changed, @changed_attributes = {}, {}, {}
1450:         @readonly = @destroyed = @marked_for_destruction = false
1451:         @persisted = true
1452:         _run_find_callbacks
1453:         _run_initialize_callbacks
1454:       end
initialize_copy(other) click to toggle source

Cloned objects have no id assigned and are treated as new records. Note that this is a “shallow” clone as it copies the object’s attributes only, not its associations. The extent of a “deep” clone is application specific and is therefore left to the application to implement according to its need.

      # File lib/active_record/base.rb, line 1416
1416:       def initialize_copy(other)
1417:         _run_after_initialize_callbacks if respond_to?(:_run_after_initialize_callbacks)
1418:         cloned_attributes = other.clone_attributes(:read_attribute_before_type_cast)
1419:         cloned_attributes.delete(self.class.primary_key)
1420: 
1421:         @attributes = cloned_attributes
1422: 
1423:         @changed_attributes = {}
1424:         attributes_from_column_definition.each do |attr, orig_value|
1425:           @changed_attributes[attr] = orig_value if field_changed?(attr, orig_value, @attributes[attr])
1426:         end
1427: 
1428:         clear_aggregation_cache
1429:         clear_association_cache
1430:         @attributes_cache = {}
1431:         @persisted = false
1432:         ensure_proper_type
1433: 
1434:         populate_with_current_scope_attributes
1435:       end
inspect() click to toggle source

Returns the contents of the record as a nicely formatted string.

      # File lib/active_record/base.rb, line 1666
1666:       def inspect
1667:         attributes_as_nice_string = self.class.column_names.collect { |name|
1668:           if has_attribute?(name) || !persisted?
1669:             "#{name}: #{attribute_for_inspect(name)}"
1670:           end
1671:         }.compact.join(", ")
1672:         "#<#{self.class} #{attributes_as_nice_string}>"
1673:       end
readonly!() click to toggle source

Marks this record as read only.

      # File lib/active_record/base.rb, line 1661
1661:       def readonly!
1662:         @readonly = true
1663:       end
readonly?() click to toggle source

Returns true if the record is read only. Records loaded through joins with piggy-back attributes will be marked as read only since they cannot be saved.

      # File lib/active_record/base.rb, line 1656
1656:       def readonly?
1657:         @readonly
1658:       end
to_param() click to toggle source

Returns a String, which Action Pack uses for constructing an URL to this object. The default implementation returns this record’s id as a String, or nil if this record’s unsaved.

For example, suppose that you have a User model, and that you have a resources :users route. Normally, user_path will construct a path with the user object’s ‘id’ in it:

  user = User.find_by_name('Phusion')
  user_path(user)  # => "/users/1"

You can override to_param in your model to make user_path construct a path using the user’s name instead of the user’s id:

  class User < ActiveRecord::Base
    def to_param  # overridden
      name
    end
  end

  user = User.find_by_name('Phusion')
  user_path(user)  # => "/users/Phusion"
      # File lib/active_record/base.rb, line 1478
1478:       def to_param
1479:         # We can't use alias_method here, because method 'id' optimizes itself on the fly.
1480:         id && id.to_s # Be sure to stringify the id for routes
1481:       end

Protected Instance Methods

clone_attribute_value(reader_method, attribute_name) click to toggle source
      # File lib/active_record/base.rb, line 1683
1683:       def clone_attribute_value(reader_method, attribute_name)
1684:         value = send(reader_method, attribute_name)
1685:         value.duplicable? ? value.clone : value
1686:       rescue TypeError, NoMethodError
1687:         value
1688:       end
clone_attributes(reader_method = :read_attribute, attributes = {}) click to toggle source
      # File lib/active_record/base.rb, line 1676
1676:       def clone_attributes(reader_method = :read_attribute, attributes = {})
1677:         attribute_names.each do |name|
1678:           attributes[name] = clone_attribute_value(reader_method, name)
1679:         end
1680:         attributes
1681:       end

Private Instance Methods

arel_attributes_values(include_primary_key = true, include_readonly_attributes = true, attribute_names = @attributes.keys) click to toggle source

Returns a copy of the attributes hash where all the values have been safely quoted for use in an Arel insert/update method.

      # File lib/active_record/base.rb, line 1712
1712:       def arel_attributes_values(include_primary_key = true, include_readonly_attributes = true, attribute_names = @attributes.keys)
1713:         attrs = {}
1714:         attribute_names.each do |name|
1715:           if (column = column_for_attribute(name)) && (include_primary_key || !column.primary)
1716: 
1717:             if include_readonly_attributes || (!include_readonly_attributes && !self.class.readonly_attributes.include?(name))
1718:               value = read_attribute(name)
1719: 
1720:               if value && self.class.serialized_attributes.key?(name)
1721:                 value = YAML.dump value
1722:               end
1723:               attrs[self.class.arel_table[name]] = value
1724:             end
1725:           end
1726:         end
1727:         attrs
1728:       end
assign_multiparameter_attributes(pairs) click to toggle source

Instantiates objects for all attribute classes that needs more than one constructor parameter. This is done by calling new on the column type or aggregation type (through composed_of) object with these parameters. So having the pairs written_on(1) = “2004”, written_on(2) = “6”, written_on(3) = “24”, will instantiate written_on (a date type) with Date.new(“2004”, “6”, “24”). You can also specify a typecast character in the parentheses to have the parameters typecasted before they’re used in the constructor. Use i for Fixnum, f for Float, s for String, and a for Array. If all the values for a given attribute are empty, the attribute will be set to nil.

      # File lib/active_record/base.rb, line 1748
1748:       def assign_multiparameter_attributes(pairs)
1749:         execute_callstack_for_multiparameter_attributes(
1750:           extract_callstack_for_multiparameter_attributes(pairs)
1751:         )
1752:       end
comma_pair_list(hash) click to toggle source

Returns a comma-separated pair list, like “key1 = val1, key2 = val2”.

      # File lib/active_record/base.rb, line 1823
1823:       def comma_pair_list(hash)
1824:         hash.map { |k,v| "#{k} = #{v}" }.join(", ")
1825:       end
convert_number_column_value(value) click to toggle source
      # File lib/active_record/base.rb, line 1835
1835:       def convert_number_column_value(value)
1836:         if value == false
1837:           0
1838:         elsif value == true
1839:           1
1840:         elsif value.is_a?(String) && value.blank?
1841:           nil
1842:         else
1843:           value
1844:         end
1845:       end
ensure_proper_type() click to toggle source

Sets the attribute used for single table inheritance to this class name if this is not the ActiveRecord::Base descendant. Considering the hierarchy Reply < Message < ActiveRecord::Base, this makes it possible to do Reply.new without having to set Reply = "Reply" yourself. No such attribute would be set for objects of the Message class in that example.

      # File lib/active_record/base.rb, line 1697
1697:       def ensure_proper_type
1698:         unless self.class.descends_from_active_record?
1699:           write_attribute(self.class.inheritance_column, self.class.sti_name)
1700:         end
1701:       end
execute_callstack_for_multiparameter_attributes(callstack) click to toggle source
      # File lib/active_record/base.rb, line 1762
1762:       def execute_callstack_for_multiparameter_attributes(callstack)
1763:         errors = []
1764:         callstack.each do |name, values_with_empty_parameters|
1765:           begin
1766:             klass = (self.class.reflect_on_aggregation(name.to_sym) || column_for_attribute(name)).klass
1767:             # in order to allow a date to be set without a year, we must keep the empty values.
1768:             # Otherwise, we wouldn't be able to distinguish it from a date with an empty day.
1769:             values = values_with_empty_parameters.reject { |v| v.nil? }
1770: 
1771:             if values.empty?
1772:               send(name + "=", nil)
1773:             else
1774: 
1775:               value = if Time == klass
1776:                 instantiate_time_object(name, values)
1777:               elsif Date == klass
1778:                 begin
1779:                   values = values_with_empty_parameters.collect do |v| v.nil? ? 1 : v end
1780:                   Date.new(*values)
1781:                 rescue ArgumentError => ex # if Date.new raises an exception on an invalid date
1782:                   instantiate_time_object(name, values).to_date # we instantiate Time object and convert it back to a date thus using Time's logic in handling invalid dates
1783:                 end
1784:               else
1785:                 klass.new(*values)
1786:               end
1787: 
1788:               send(name + "=", value)
1789:             end
1790:           rescue => ex
1791:             errors << AttributeAssignmentError.new("error on assignment #{values.inspect} to #{name}", ex, name)
1792:           end
1793:         end
1794:         unless errors.empty?
1795:           raise MultiparameterAssignmentErrors.new(errors), "#{errors.size} error(s) on assignment of multiparameter attributes"
1796:         end
1797:       end
extract_callstack_for_multiparameter_attributes(pairs) click to toggle source
      # File lib/active_record/base.rb, line 1799
1799:       def extract_callstack_for_multiparameter_attributes(pairs)
1800:         attributes = { }
1801: 
1802:         for pair in pairs
1803:           multiparameter_name, value = pair
1804:           attribute_name = multiparameter_name.split("(").first
1805:           attributes[attribute_name] = [] unless attributes.include?(attribute_name)
1806: 
1807:           parameter_value = value.empty? ? nil : type_cast_attribute_value(multiparameter_name, value)
1808:           attributes[attribute_name] << [ find_parameter_position(multiparameter_name), parameter_value ]
1809:         end
1810: 
1811:         attributes.each { |name, values| attributes[name] = values.sort_by{ |v| v.first }.collect { |v| v.last } }
1812:       end
find_parameter_position(multiparameter_name) click to toggle source
      # File lib/active_record/base.rb, line 1818
1818:       def find_parameter_position(multiparameter_name)
1819:         multiparameter_name.scan(/\(([0-9]*).*\)/).first.first
1820:       end
instantiate_time_object(name, values) click to toggle source
      # File lib/active_record/base.rb, line 1754
1754:       def instantiate_time_object(name, values)
1755:         if self.class.send(:create_time_zone_conversion_attribute?, name, column_for_attribute(name))
1756:           Time.zone.local(*values)
1757:         else
1758:           Time.time_with_datetime_fallback(@@default_timezone, *values)
1759:         end
1760:       end
interpolate_sql(sql, record = nil) click to toggle source

Interpolate custom SQL string in instance context. Optional record argument is meant for custom insert_sql.

      # File lib/active_record/base.rb, line 1737
1737:       def interpolate_sql(sql, record = nil)
1738:         instance_eval("%@#{sql.gsub('@', '\@')}@", __FILE__, __LINE__)
1739:       end
object_from_yaml(string) click to toggle source
      # File lib/active_record/base.rb, line 1847
1847:       def object_from_yaml(string)
1848:         return string unless string.is_a?(String) && string =~ /^---/
1849:         YAML::load(string) rescue string
1850:       end
populate_with_current_scope_attributes() click to toggle source
      # File lib/active_record/base.rb, line 1852
1852:       def populate_with_current_scope_attributes
1853:         if scope = self.class.send(:current_scoped_methods)
1854:           create_with = scope.scope_for_create
1855:           create_with.each { |att,value| self.respond_to?(:"#{att}=") && self.send("#{att}=", value) } if create_with
1856:         end
1857:       end
quote_columns(quoter, hash) click to toggle source
      # File lib/active_record/base.rb, line 1827
1827:       def quote_columns(quoter, hash)
1828:         Hash[hash.map { |name, value| [quoter.quote_column_name(name), value] }]
1829:       end
quote_value(value, column = nil) click to toggle source

Quote strings appropriately for SQL statements.

      # File lib/active_record/base.rb, line 1731
1731:       def quote_value(value, column = nil)
1732:         self.class.connection.quote(value, column)
1733:       end
quoted_comma_pair_list(quoter, hash) click to toggle source
      # File lib/active_record/base.rb, line 1831
1831:       def quoted_comma_pair_list(quoter, hash)
1832:         comma_pair_list(quote_columns(quoter, hash))
1833:       end
type_cast_attribute_value(multiparameter_name, value) click to toggle source
      # File lib/active_record/base.rb, line 1814
1814:       def type_cast_attribute_value(multiparameter_name, value)
1815:         multiparameter_name =~ /\([0-9]*([if])\)/ ? value.send("to_" + $1) : value
1816:       end

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