Ember.js rollback relationships, including deletions of child objects

Model.coffee

# RollbackAttributes should also rollback relationships
# Based on http://stackoverflow.com/a/27184207/223225 and https://github.com/emberjs/rfcs/pull/21#issuecomment-135134132

DS.Model.reopen
	rollbackAttributes: ->
		@_super()
		@rollbackRelationships()


	cacheOriginalRelations: ->
		# Save original relations values to @originalRelations
		@set 'originalRelations', {}
		# The values of those relations are intially null, even with async: false; so do findRecord to get the complete record
		@store.findRecord(@constructor.modelName, @id).then (record) =>
			record.eachRelationship (key, relationship) =>
				if relationship.kind is 'belongsTo'
					@set "originalRelations.#{key}", record.get(key)
				if relationship.kind is 'hasMany'
					@set "originalRelations.#{key}", record.get(key).toArray()


	ready: ->
		@cacheOriginalRelations()


	onReloading: (->
		unless @get('isReloading')
			@cacheOriginalRelations()
	).observes('isReloading')


	rollbackRelationships: ->
		return unless @originalRelations?

		Object.keys(@originalRelations).forEach (key) =>
			# For each relation, set the key to the original value (another record or array of records)
			if Ember.isArray(@get(key)) # Careful, as Ember.typeOf for ArrayProxy is 'instance'
				@originalRelations[key].invoke 'rollbackAttributes' # Important! Do this BEFORE setting the value, so undo any possible deletions
				@get(key).setObjects @originalRelations[key]
			if Ember.typeOf(@get(key)) is 'instance'
				@originalRelations[key].rollbackAttributes() if @originalRelations[key].rollbackAttributes? # Important! Do this BEFORE setting the value, so undo any possible deletions
				@set key, @originalRelations[key]
			else if Ember.typeOf(@get(key)) is 'null'
				@set key, @originalRelations[key]


	isDeepDirty: ->
		return if @_super('isDirty') or not @originalRelations?

		Object.keys(@originalRelations).any (key) =>
			if Ember.isArray(@get(key))
				return if @get(key).anyBy('isDirty') or @get(key).get('length') isnt @originalRelations[key].length

				dirty = no
				@get(key).forEach (item, index) =>
					if item.get('id') isnt @originalRelations[key][index].get('id')
						dirty = yes
				return dirty

			@get(key).get('isDirty') or @get(key).get('id') isnt @originalRelations[key].get('id')

emberjs/rfcs#21 (comment)