--- /dev/null
+module ActiveRecord
+ # Track unsaved attribute changes.
+ #
+ # A newly instantiated object is unchanged:
+ # person = Person.find_by_name('uncle bob')
+ # person.changed? # => false
+ #
+ # Change the name:
+ # person.name = 'Bob'
+ # person.changed? # => true
+ # person.name_changed? # => true
+ # person.name_was # => 'uncle bob'
+ # person.name_change # => ['uncle bob', 'Bob']
+ # person.name = 'Bill'
+ # person.name_change # => ['uncle bob', 'Bill']
+ #
+ # Save the changes:
+ # person.save
+ # person.changed? # => false
+ # person.name_changed? # => false
+ #
+ # Assigning the same value leaves the attribute unchanged:
+ # person.name = 'Bill'
+ # person.name_changed? # => false
+ # person.name_change # => nil
+ #
+ # Which attributes have changed?
+ # person.name = 'bob'
+ # person.changed # => ['name']
+ # person.changes # => { 'name' => ['Bill', 'bob'] }
+ #
+ # Before modifying an attribute in-place:
+ # person.name_will_change!
+ # person.name << 'by'
+ # person.name_change # => ['uncle bob', 'uncle bobby']
+ module Dirty
+ DIRTY_SUFFIXES = ['_changed?', '_change', '_will_change!', '_was']
+
+ def self.included(base)
+ base.attribute_method_suffix *DIRTY_SUFFIXES
+ base.alias_method_chain :write_attribute, :dirty
+ base.alias_method_chain :save, :dirty
+ base.alias_method_chain :save!, :dirty
+ base.alias_method_chain :update, :dirty
+ base.alias_method_chain :reload, :dirty
+
+ base.superclass_delegating_accessor :partial_updates
+ base.partial_updates = true
+
+ base.send(:extend, ClassMethods)
+ end
+
+ # Do any attributes have unsaved changes?
+ # person.changed? # => false
+ # person.name = 'bob'
+ # person.changed? # => true
+ def changed?
+ !changed_attributes.empty?
+ end
+
+ # List of attributes with unsaved changes.
+ # person.changed # => []
+ # person.name = 'bob'
+ # person.changed # => ['name']
+ def changed
+ changed_attributes.keys
+ end
+
+ # Map of changed attrs => [original value, new value].
+ # person.changes # => {}
+ # person.name = 'bob'
+ # person.changes # => { 'name' => ['bill', 'bob'] }
+ def changes
+ changed.inject({}) { |h, attr| h[attr] = attribute_change(attr); h }
+ end
+
+ # Attempts to +save+ the record and clears changed attributes if successful.
+ def save_with_dirty(*args) #:nodoc:
+ if status = save_without_dirty(*args)
+ changed_attributes.clear
+ end
+ status
+ end
+
+ # Attempts to <tt>save!</tt> the record and clears changed attributes if successful.
+ def save_with_dirty!(*args) #:nodoc:
+ status = save_without_dirty!(*args)
+ changed_attributes.clear
+ status
+ end
+
+ # <tt>reload</tt> the record and clears changed attributes.
+ def reload_with_dirty(*args) #:nodoc:
+ record = reload_without_dirty(*args)
+ changed_attributes.clear
+ record
+ end
+
+ private
+ # Map of change <tt>attr => original value</tt>.
+ def changed_attributes
+ @changed_attributes ||= {}
+ end
+
+ # Handle <tt>*_changed?</tt> for +method_missing+.
+ def attribute_changed?(attr)
+ changed_attributes.include?(attr)
+ end
+
+ # Handle <tt>*_change</tt> for +method_missing+.
+ def attribute_change(attr)
+ [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr)
+ end
+
+ # Handle <tt>*_was</tt> for +method_missing+.
+ def attribute_was(attr)
+ attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
+ end
+
+ # Handle <tt>*_will_change!</tt> for +method_missing+.
+ def attribute_will_change!(attr)
+ changed_attributes[attr] = clone_attribute_value(:read_attribute, attr)
+ end
+
+ # Wrap write_attribute to remember original attribute value.
+ def write_attribute_with_dirty(attr, value)
+ attr = attr.to_s
+
+ # The attribute already has an unsaved change.
+ if changed_attributes.include?(attr)
+ old = changed_attributes[attr]
+ changed_attributes.delete(attr) unless field_changed?(attr, old, value)
+ else
+ old = clone_attribute_value(:read_attribute, attr)
+ changed_attributes[attr] = old if field_changed?(attr, old, value)
+ end
+
+ # Carry on.
+ write_attribute_without_dirty(attr, value)
+ end
+
+ def update_with_dirty
+ if partial_updates?
+ # Serialized attributes should always be written in case they've been
+ # changed in place.
+ update_without_dirty(changed | self.class.serialized_attributes.keys)
+ else
+ update_without_dirty
+ end
+ end
+
+ def field_changed?(attr, old, value)
+ if column = column_for_attribute(attr)
+ if column.type == :integer && column.null && (old.nil? || old == 0)
+ # For nullable integer columns, NULL gets stored in database for blank (i.e. '') values.
+ # Hence we don't record it as a change if the value changes from nil to ''.
+ # If an old value of 0 is set to '' we want this to get changed to nil as otherwise it'll
+ # be typecast back to 0 (''.to_i => 0)
+ value = nil if value.blank?
+ else
+ value = column.type_cast(value)
+ end
+ end
+
+ old != value
+ end
+
+ module ClassMethods
+ def self.extended(base)
+ base.metaclass.alias_method_chain(:alias_attribute, :dirty)
+ end
+
+ def alias_attribute_with_dirty(new_name, old_name)
+ alias_attribute_without_dirty(new_name, old_name)
+ DIRTY_SUFFIXES.each do |suffix|
+ module_eval <<-STR, __FILE__, __LINE__+1
+ def #{new_name}#{suffix}; self.#{old_name}#{suffix}; end
+ STR
+ end
+ end
+ end
+ end
+end
projects / depot.git / blobdiff