Adds a new column to the named table. See TableDefinition#column for details of the options you can use.
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 187 def add_column(table_name, column_name, type, options = {}) add_column_sql = "ALTER TABLE #{quote_table_name(table_name)} ADD #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}" add_column_options!(add_column_sql, options) execute(add_column_sql) end
Adds a new index to the table. column_name can be a single Symbol, or an Array of Symbols.
The index will be named after the table and the first column name, unless you pass :name as an option.
When creating an index on multiple columns, the first column is used as a name for the index. For example, when you specify an index on two columns [:first, :last], the DBMS creates an index for both columns as well as an index for the first column :first. Using just the first name for this index makes sense, because you will never have to create a singular index with this name.
add_index(:suppliers, :name)
generates
CREATE INDEX suppliers_name_index ON suppliers(name)
add_index(:accounts, [:branch_id, :party_id], :unique => true)
generates
CREATE UNIQUE INDEX accounts_branch_id_party_id_index ON accounts(branch_id, party_id)
add_index(:accounts, [:branch_id, :party_id], :unique => true, :name => 'by_branch_party')
generates
CREATE UNIQUE INDEX by_branch_party ON accounts(branch_id, party_id)
add_index(:accounts, :name, :name => 'by_name', :length => 10)
generates
CREATE INDEX by_name ON accounts(name(10)) add_index(:accounts, [:name, :surname], :name => 'by_name_surname', :length => {:name => 10, :surname => 15})
generates
CREATE INDEX by_name_surname ON accounts(name(10), surname(15))
Note: SQLite doesn’t support index length
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 271 def add_index(table_name, column_name, options = {}) column_names = Array(column_name) index_name = index_name(table_name, :column => column_names) if Hash === options # legacy support, since this param was a string index_type = options[:unique] ? "UNIQUE" : "" index_name = options[:name].to_s if options[:name] else index_type = options end if index_name.length > index_name_length @logger.warn("Index name '#{index_name}' on table '#{table_name}' is too long; the limit is #{index_name_length} characters. Skipping.") return end if index_exists?(table_name, index_name, false) @logger.warn("Index name '#{index_name}' on table '#{table_name}' already exists. Skipping.") return end quoted_column_names = quoted_columns_for_index(column_names, options).join(", ") execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} (#{quoted_column_names})" end
ORDER BY clause for the passed order option. PostgreSQL overrides this due to its stricter standards compliance.
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 459 def add_order_by_for_association_limiting!(sql, options) sql << " ORDER BY #{options[:order]}" end
Adds timestamps (created_at and updated_at) columns to the named table.
add_timestamps(:suppliers)
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 466 def add_timestamps(table_name) add_column table_name, :created_at, :datetime add_column table_name, :updated_at, :datetime end
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 390 def assume_migrated_upto_version(version, migrations_path = ActiveRecord::Migrator.migrations_path) version = version.to_i sm_table = quote_table_name(ActiveRecord::Migrator.schema_migrations_table_name) migrated = select_values("SELECT version FROM #{sm_table}").map(&:to_i) versions = Dir["#{migrations_path}/[0-9]*_*.rb"].map do |filename| filename.split('/').last.split('_').first.to_i end unless migrated.include?(version) execute "INSERT INTO #{sm_table} (version) VALUES ('#{version}')" end inserted = Set.new (versions - migrated).each do |v| if inserted.include?(v) raise "Duplicate migration #{v}. Please renumber your migrations to resolve the conflict." elsif v < version execute "INSERT INTO #{sm_table} (version) VALUES ('#{v}')" inserted << v end end end
Changes the column’s definition according to the new options. See TableDefinition#column for details of the options you can use.
change_column(:suppliers, :name, :string, :limit => 80) change_column(:accounts, :description, :text)
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 210 def change_column(table_name, column_name, type, options = {}) raise NotImplementedError, "change_column is not implemented" end
Sets a new default value for a column. If you want to set the default value to NULL, you are out of luck. You need to DatabaseStatements#execute the appropriate SQL statement yourself.
change_column_default(:suppliers, :qualification, 'new') change_column_default(:accounts, :authorized, 1)
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 220 def change_column_default(table_name, column_name, default) raise NotImplementedError, "change_column_default is not implemented" end
A block for changing columns in table.
# change_table() yields a Table instance change_table(:suppliers) do |t| t.column :name, :string, :limit => 60 # Other column alterations here end
change_table(:suppliers) do |t| t.column :name, :string, :limit => 60 end
change_table(:suppliers) do |t| t.integer :width, :height, :null => false, :default => 0 end
change_table(:suppliers) do |t| t.timestamps end
change_table(:suppliers) do |t| t.references :company end
Creates a company_id(integer) column
change_table(:suppliers) do |t| t.belongs_to :company, :polymorphic => true end
Creates company_type(varchar) and company_id(integer) columns
change_table(:suppliers) do |t| t.remove :company end
change_table(:suppliers) do |t| t.remove :company_id t.remove :width, :height end
change_table(:suppliers) do |t| t.remove_index :company_id end
See also Table for details on all of the various column transformation
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 169 def change_table(table_name) yield Table.new(table_name, self) end
Returns an array of Column objects for the table specified by table_name. See the concrete implementation for details on the expected parameter values.
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 27 def columns(table_name, name = nil) end
Creates a new table with the name table_name. table_name may either be a String or a Symbol.
There are two ways to work with create_table. You can use the block form or the regular form, like this:
# create_table() passes a TableDefinition object to the block. # This form will not only create the table, but also columns for the # table. create_table(:suppliers) do |t| t.column :name, :string, :limit => 60 # Other fields here end
# Creates a table called 'suppliers' with no columns. create_table(:suppliers) # Add a column to 'suppliers'. add_column(:suppliers, :name, :string, {:limit => 60})
The options hash can include the following keys:
Whether to automatically add a primary key column. Defaults to true. Join tables for has_and_belongs_to_many should set :id => false.
The name of the primary key, if one is to be added automatically. Defaults to id.
Any extra options you want appended to the table definition.
Make a temporary table.
Set to true to drop the table before creating it. Defaults to false.
create_table(:suppliers, :options => 'ENGINE=InnoDB DEFAULT CHARSET=utf8')
generates:
CREATE TABLE suppliers ( id int(11) DEFAULT NULL auto_increment PRIMARY KEY ) ENGINE=InnoDB DEFAULT CHARSET=utf8
create_table(:objects, :primary_key => 'guid') do |t| t.column :name, :string, :limit => 80 end
generates:
CREATE TABLE objects ( guid int(11) DEFAULT NULL auto_increment PRIMARY KEY, name varchar(80) )
create_table(:categories_suppliers, :id => false) do |t| t.column :category_id, :integer t.column :supplier_id, :integer end
generates:
CREATE TABLE categories_suppliers ( category_id int, supplier_id int )
See also TableDefinition#column for details on how to create columns.
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 95 def create_table(table_name, options = {}) table_definition = TableDefinition.new(self) table_definition.primary_key(options[:primary_key] || Base.get_primary_key(table_name.to_s.singularize)) unless options[:id] == false yield table_definition if block_given? if options[:force] && table_exists?(table_name) drop_table(table_name, options) end create_sql = "CREATE#{' TEMPORARY' if options[:temporary]} TABLE " create_sql << "#{quote_table_name(table_name)} (" create_sql << table_definition.to_sql create_sql << ") #{options[:options]}" execute create_sql end
SELECT DISTINCT clause for a given set of columns and a given ORDER BY clause. Both PostgreSQL and Oracle overrides this for custom DISTINCT syntax.
distinct("posts.id", "posts.created_at desc")
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 453 def distinct(columns, order_by) "DISTINCT #{columns}" end
Drops a table from the database.
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 181 def drop_table(table_name, options = {}) execute "DROP TABLE #{quote_table_name(table_name)}" end
Verify the existence of an index.
The default argument is returned if the underlying implementation does not define the indexes method, as there’s no way to determine the correct answer in that case.
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 348 def index_exists?(table_name, index_name, default) return default unless respond_to?(:indexes) index_name = index_name.to_s indexes(table_name).detect { |i| i.name == index_name } end
Should not be called normally, but this operation is non-destructive. The migrations module handles this automatically.
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 367 def initialize_schema_migrations_table sm_table = ActiveRecord::Migrator.schema_migrations_table_name unless tables.detect { |t| t == sm_table } create_table(sm_table, :id => false) do |schema_migrations_table| schema_migrations_table.column :version, :string, :null => false end add_index sm_table, :version, :unique => true, :name => "#{Base.table_name_prefix}unique_schema_migrations#{Base.table_name_suffix}" # Backwards-compatibility: if we find schema_info, assume we've # migrated up to that point: si_table = Base.table_name_prefix + 'schema_info' + Base.table_name_suffix if tables.detect { |t| t == si_table } old_version = select_value("SELECT version FROM #{quote_table_name(si_table)}").to_i assume_migrated_upto_version(old_version) drop_table(si_table) end end end
Returns a Hash of mappings from the abstract data types to the native database types. See TableDefinition#column for details on the recognized abstract data types.
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 7 def native_database_types {} end
Removes the column(s) from the table definition.
remove_column(:suppliers, :qualification) remove_columns(:suppliers, :qualification, :experience)
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 197 def remove_column(table_name, *column_names) raise ArgumentError.new("You must specify at least one column name. Example: remove_column(:people, :first_name)") if column_names.empty? column_names.flatten.each do |column_name| execute "ALTER TABLE #{quote_table_name(table_name)} DROP #{quote_column_name(column_name)}" end end
Remove the given index from the table.
Remove the suppliers_name_index in the suppliers table.
remove_index :suppliers, :name
Remove the index named accounts_branch_id_index in the accounts table.
remove_index :accounts, :column => :branch_id
Remove the index named accounts_branch_id_party_id_index in the accounts table.
remove_index :accounts, :column => [:branch_id, :party_id]
Remove the index named by_branch_party in the accounts table.
remove_index :accounts, :name => :by_branch_party
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 305 def remove_index(table_name, options = {}) index_name = index_name(table_name, options) unless index_exists?(table_name, index_name, true) @logger.warn("Index name '#{index_name}' on table '#{table_name}' does not exist. Skipping.") return end remove_index!(table_name, index_name) end
Removes the timestamp columns (created_at and updated_at) from the table definition.
remove_timestamps(:suppliers)
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 474 def remove_timestamps(table_name) remove_column table_name, :updated_at remove_column table_name, :created_at end
Renames a column.
rename_column(:suppliers, :description, :name)
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 227 def rename_column(table_name, column_name, new_column_name) raise NotImplementedError, "rename_column is not implemented" end
Rename an index.
Rename the index_people_on_last_name index to index_users_on_last_name
rename_index :people, 'index_people_on_last_name', 'index_users_on_last_name'
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 322 def rename_index(table_name, old_name, new_name) # this is a naive implementation; some DBs may support this more efficiently (Postgres, for instance) old_index_def = indexes(table_name).detect { |i| i.name == old_name } return unless old_index_def remove_index(table_name, :name => old_name) add_index(table_name, old_index_def.columns, :name => new_name, :unique => old_index_def.unique) end
Renames a table.
rename_table('octopuses', 'octopi')
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 176 def rename_table(table_name, new_name) raise NotImplementedError, "rename_table is not implemented" end
Returns a string of CREATE TABLE SQL statement(s) for recreating the entire structure of the database.
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 356 def structure_dump end
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 485 def options_include_default?(options) options.include?(:default) && !(options[:null] == false && options[:default].nil?) end
Overridden by the mysql adapter for supporting index lengths
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 481 def quoted_columns_for_index(column_names, options = {}) column_names.map {|name| quote_column_name(name) } end
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