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