Instance methods included into Hash for dealing with manipulation of hashes in the specific format of ActiveRecord::Base#changes.
When called on a hash of changes and given a second hash of changes as an
argument, append_changes
will run the second hash on top of
the first, updating the last element of each array value with its own, or
creating its own key/value pair for missing keys. Resulting non-unique
array values are removed.
first = {
"first_name" => ["Steve", "Stephen"], "age" => [25, 26]
} second = {
"first_name" => ["Stephen", "Steve"], "last_name" => ["Richert", "Jobs"], "age" => [26, 54]
} first.append_changes(second) # => {
"last_name" => ["Richert", "Jobs"], "age" => [25, 54]
}
# File lib/vestal_versions/changes.rb, line 87 def append_changes(changes) changes.inject(self) do |new_changes, (attribute, change)| new_change = [new_changes.fetch(attribute, change).first, change.last] new_changes.merge(attribute => new_change) end.reject do |attribute, change| change.first == change.last end end
Destructively appends a given hash of changes onto an existing hash of changes.
# File lib/vestal_versions/changes.rb, line 97 def append_changes!(changes) replace(append_changes(changes)) end
Appends the existing hash of changes onto a given hash of changes. Relates
to the append_changes
method in the same way that
Hash#reverse_merge relates to Hash#merge.
# File lib/vestal_versions/changes.rb, line 104 def prepend_changes(changes) changes.append_changes(self) end
Destructively prepends a given hash of changes onto an existing hash of changes.
# File lib/vestal_versions/changes.rb, line 109 def prepend_changes!(changes) replace(prepend_changes(changes)) end
Reverses the array values of a hash of changes. Useful for reversion both backward and forward through a record's history of changes.
# File lib/vestal_versions/changes.rb, line 115 def reverse_changes inject({}){|nc,(a,c)| nc.merge!(a => c.reverse) } end
Destructively reverses the array values of a hash of changes.
# File lib/vestal_versions/changes.rb, line 120 def reverse_changes! replace(reverse_changes) end