# File lib/active_record/attribute_methods/dirty.rb, line 80 def _field_changed?(attr, old, value) if column = column_for_attribute(attr) if column.number? && (changes_from_nil_to_empty_string?(column, old, value) || changes_from_zero_to_string?(old, value)) value = nil else value = column.type_cast(value) end end old != value end
# File lib/active_record/attribute_methods/dirty.rb, line 97 def changes_from_nil_to_empty_string?(column, old, value) # For nullable numeric 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) column.null && (old.nil? || old == 0) && value.blank? end
# File lib/active_record/attribute_methods/dirty.rb, line 105 def changes_from_zero_to_string?(old, value) # For columns with old 0 and value non-empty string old == 0 && value.is_a?(String) && value.present? && value != '0' end
# File lib/active_record/attribute_methods/dirty.rb, line 93 def clone_with_time_zone_conversion_attribute?(attr, old) old.class.name == "Time" && time_zone_aware_attributes && !self.skip_time_zone_conversion_for_attributes.include?(attr.to_sym) end
# File lib/active_record/attribute_methods/dirty.rb, line 70 def update(*) if partial_updates? # Serialized attributes should always be written in case they've been # changed in place. super(changed | (attributes.keys & self.class.serialized_attributes.keys)) else super end end
Wrap #write_attribute to remember original attribute value.
# File lib/active_record/attribute_methods/dirty.rb, line 52 def write_attribute(attr, value) attr = attr.to_s # The attribute already has an unsaved change. if attribute_changed?(attr) old = @changed_attributes[attr] @changed_attributes.delete(attr) unless _field_changed?(attr, old, value) else old = clone_attribute_value(:read_attribute, attr) # Save Time objects as TimeWithZone if time_zone_aware_attributes == true old = old.in_time_zone if clone_with_time_zone_conversion_attribute?(attr, old) @changed_attributes[attr] = old if _field_changed?(attr, old, value) end # Carry on. super(attr, value) end