require "active_support/core_ext/hash/except" require "active_support/core_ext/object/try" require "active_support/core_ext/hash/indifferent_access" module ActiveRecord module NestedAttributes #:nodoc: class TooManyRecords < ActiveRecordError end extend ActiveSupport::Concern included do class_attribute :nested_attributes_options, instance_writer: false self.nested_attributes_options = {} end # = Active Record Nested Attributes # # Nested attributes allow you to save attributes on associated records # through the parent. By default nested attribute updating is turned off # and you can enable it using the accepts_nested_attributes_for class # method. When you enable nested attributes an attribute writer is # defined on the model. # # The attribute writer is named after the association, which means that # in the following example, two new methods are added to your model: # # author_attributes=(attributes) and # pages_attributes=(attributes). # # class Book < ActiveRecord::Base # has_one :author # has_many :pages # # accepts_nested_attributes_for :author, :pages # end # # Note that the :autosave option is automatically enabled on every # association that accepts_nested_attributes_for is used for. # # === One-to-one # # Consider a Member model that has one Avatar: # # class Member < ActiveRecord::Base # has_one :avatar # accepts_nested_attributes_for :avatar # end # # Enabling nested attributes on a one-to-one association allows you to # create the member and avatar in one go: # # params = { member: { name: 'Jack', avatar_attributes: { icon: 'smiling' } } } # member = Member.create(params[:member]) # member.avatar.id # => 2 # member.avatar.icon # => 'smiling' # # It also allows you to update the avatar through the member: # # params = { member: { avatar_attributes: { id: '2', icon: 'sad' } } } # member.update params[:member] # member.avatar.icon # => 'sad' # # By default you will only be able to set and update attributes on the # associated model. If you want to destroy the associated model through the # attributes hash, you have to enable it first using the # :allow_destroy option. # # class Member < ActiveRecord::Base # has_one :avatar # accepts_nested_attributes_for :avatar, allow_destroy: true # end # # Now, when you add the _destroy key to the attributes hash, with a # value that evaluates to +true+, you will destroy the associated model: # # member.avatar_attributes = { id: '2', _destroy: '1' } # member.avatar.marked_for_destruction? # => true # member.save # member.reload.avatar # => nil # # Note that the model will _not_ be destroyed until the parent is saved. # # Also note that the model will not be destroyed unless you also specify # its id in the updated hash. # # === One-to-many # # Consider a member that has a number of posts: # # class Member < ActiveRecord::Base # has_many :posts # accepts_nested_attributes_for :posts # end # # You can now set or update attributes on the associated posts through # an attribute hash for a member: include the key +:posts_attributes+ # with an array of hashes of post attributes as a value. # # For each hash that does _not_ have an id key a new record will # be instantiated, unless the hash also contains a _destroy key # that evaluates to +true+. # # params = { member: { # name: 'joe', posts_attributes: [ # { title: 'Kari, the awesome Ruby documentation browser!' }, # { title: 'The egalitarian assumption of the modern citizen' }, # { title: '', _destroy: '1' } # this will be ignored # ] # }} # # member = Member.create(params[:member]) # member.posts.length # => 2 # member.posts.first.title # => 'Kari, the awesome Ruby documentation browser!' # member.posts.second.title # => 'The egalitarian assumption of the modern citizen' # # You may also set a +:reject_if+ proc to silently ignore any new record # hashes if they fail to pass your criteria. For example, the previous # example could be rewritten as: # # class Member < ActiveRecord::Base # has_many :posts # accepts_nested_attributes_for :posts, reject_if: proc { |attributes| attributes['title'].blank? } # end # # params = { member: { # name: 'joe', posts_attributes: [ # { title: 'Kari, the awesome Ruby documentation browser!' }, # { title: 'The egalitarian assumption of the modern citizen' }, # { title: '' } # this will be ignored because of the :reject_if proc # ] # }} # # member = Member.create(params[:member]) # member.posts.length # => 2 # member.posts.first.title # => 'Kari, the awesome Ruby documentation browser!' # member.posts.second.title # => 'The egalitarian assumption of the modern citizen' # # Alternatively, +:reject_if+ also accepts a symbol for using methods: # # class Member < ActiveRecord::Base # has_many :posts # accepts_nested_attributes_for :posts, reject_if: :new_record? # end # # class Member < ActiveRecord::Base # has_many :posts # accepts_nested_attributes_for :posts, reject_if: :reject_posts # # def reject_posts(attributes) # attributes['title'].blank? # end # end # # If the hash contains an id key that matches an already # associated record, the matching record will be modified: # # member.attributes = { # name: 'Joe', # posts_attributes: [ # { id: 1, title: '[UPDATED] An, as of yet, undisclosed awesome Ruby documentation browser!' }, # { id: 2, title: '[UPDATED] other post' } # ] # } # # member.posts.first.title # => '[UPDATED] An, as of yet, undisclosed awesome Ruby documentation browser!' # member.posts.second.title # => '[UPDATED] other post' # # However, the above applies if the parent model is being updated as well. # For example, If you wanted to create a +member+ named _joe_ and wanted to # update the +posts+ at the same time, that would give an # ActiveRecord::RecordNotFound error. # # By default the associated records are protected from being destroyed. If # you want to destroy any of the associated records through the attributes # hash, you have to enable it first using the :allow_destroy # option. This will allow you to also use the _destroy key to # destroy existing records: # # class Member < ActiveRecord::Base # has_many :posts # accepts_nested_attributes_for :posts, allow_destroy: true # end # # params = { member: { # posts_attributes: [{ id: '2', _destroy: '1' }] # }} # # member.attributes = params[:member] # member.posts.detect { |p| p.id == 2 }.marked_for_destruction? # => true # member.posts.length # => 2 # member.save # member.reload.posts.length # => 1 # # Nested attributes for an associated collection can also be passed in # the form of a hash of hashes instead of an array of hashes: # # Member.create( # name: 'joe', # posts_attributes: { # first: { title: 'Foo' }, # second: { title: 'Bar' } # } # ) # # has the same effect as # # Member.create( # name: 'joe', # posts_attributes: [ # { title: 'Foo' }, # { title: 'Bar' } # ] # ) # # The keys of the hash which is the value for +:posts_attributes+ are # ignored in this case. # However, it is not allowed to use 'id' or :id for one of # such keys, otherwise the hash will be wrapped in an array and # interpreted as an attribute hash for a single post. # # Passing attributes for an associated collection in the form of a hash # of hashes can be used with hashes generated from HTTP/HTML parameters, # where there may be no natural way to submit an array of hashes. # # === Saving # # All changes to models, including the destruction of those marked for # destruction, are saved and destroyed automatically and atomically when # the parent model is saved. This happens inside the transaction initiated # by the parent's save method. See ActiveRecord::AutosaveAssociation. # # === Validating the presence of a parent model # # If you want to validate that a child record is associated with a parent # record, you can use the +validates_presence_of+ method and the +:inverse_of+ # key as this example illustrates: # # class Member < ActiveRecord::Base # has_many :posts, inverse_of: :member # accepts_nested_attributes_for :posts # end # # class Post < ActiveRecord::Base # belongs_to :member, inverse_of: :posts # validates_presence_of :member # end # # Note that if you do not specify the +:inverse_of+ option, then # Active Record will try to automatically guess the inverse association # based on heuristics. # # For one-to-one nested associations, if you build the new (in-memory) # child object yourself before assignment, then this module will not # overwrite it, e.g.: # # class Member < ActiveRecord::Base # has_one :avatar # accepts_nested_attributes_for :avatar # # def avatar # super || build_avatar(width: 200) # end # end # # member = Member.new # member.avatar_attributes = {icon: 'sad'} # member.avatar.width # => 200 module ClassMethods REJECT_ALL_BLANK_PROC = proc { |attributes| attributes.all? { |key, value| key == "_destroy" || value.blank? } } # Defines an attributes writer for the specified association(s). # # Supported options: # [:allow_destroy] # If true, destroys any members from the attributes hash with a # _destroy key and a value that evaluates to +true+ # (eg. 1, '1', true, or 'true'). This option is off by default. # [:reject_if] # Allows you to specify a Proc or a Symbol pointing to a method # that checks whether a record should be built for a certain attribute # hash. The hash is passed to the supplied Proc or the method # and it should return either +true+ or +false+. When no +:reject_if+ # is specified, a record will be built for all attribute hashes that # do not have a _destroy value that evaluates to true. # Passing :all_blank instead of a Proc will create a proc # that will reject a record where all the attributes are blank excluding # any value for +_destroy+. # [:limit] # Allows you to specify the maximum number of associated records that # can be processed with the nested attributes. Limit also can be specified # as a Proc or a Symbol pointing to a method that should return a number. # If the size of the nested attributes array exceeds the specified limit, # NestedAttributes::TooManyRecords exception is raised. If omitted, any # number of associations can be processed. # Note that the +:limit+ option is only applicable to one-to-many # associations. # [:update_only] # For a one-to-one association, this option allows you to specify how # nested attributes are going to be used when an associated record already # exists. In general, an existing record may either be updated with the # new set of attribute values or be replaced by a wholly new record # containing those values. By default the +:update_only+ option is +false+ # and the nested attributes are used to update the existing record only # if they include the record's :id value. Otherwise a new # record will be instantiated and used to replace the existing one. # However if the +:update_only+ option is +true+, the nested attributes # are used to update the record's attributes always, regardless of # whether the :id is present. The option is ignored for collection # associations. # # Examples: # # creates avatar_attributes= # accepts_nested_attributes_for :avatar, reject_if: proc { |attributes| attributes['name'].blank? } # # creates avatar_attributes= # accepts_nested_attributes_for :avatar, reject_if: :all_blank # # creates avatar_attributes= and posts_attributes= # accepts_nested_attributes_for :avatar, :posts, allow_destroy: true def accepts_nested_attributes_for(*attr_names) options = { allow_destroy: false, update_only: false } options.update(attr_names.extract_options!) options.assert_valid_keys(:allow_destroy, :reject_if, :limit, :update_only) options[:reject_if] = REJECT_ALL_BLANK_PROC if options[:reject_if] == :all_blank attr_names.each do |association_name| if reflection = _reflect_on_association(association_name) reflection.autosave = true define_autosave_validation_callbacks(reflection) nested_attributes_options = self.nested_attributes_options.dup nested_attributes_options[association_name.to_sym] = options self.nested_attributes_options = nested_attributes_options type = (reflection.collection? ? :collection : :one_to_one) generate_association_writer(association_name, type) else raise ArgumentError, "No association found for name `#{association_name}'. Has it been defined yet?" end end end private # Generates a writer method for this association. Serves as a point for # accessing the objects in the association. For example, this method # could generate the following: # # def pirate_attributes=(attributes) # assign_nested_attributes_for_one_to_one_association(:pirate, attributes) # end # # This redirects the attempts to write objects in an association through # the helper methods defined below. Makes it seem like the nested # associations are just regular associations. def generate_association_writer(association_name, type) generated_association_methods.module_eval <<-eoruby, __FILE__, __LINE__ + 1 if method_defined?(:#{association_name}_attributes=) remove_method(:#{association_name}_attributes=) end def #{association_name}_attributes=(attributes) assign_nested_attributes_for_#{type}_association(:#{association_name}, attributes) end eoruby end end # Returns ActiveRecord::AutosaveAssociation::marked_for_destruction? It's # used in conjunction with fields_for to build a form element for the # destruction of this association. # # See ActionView::Helpers::FormHelper::fields_for for more info. def _destroy marked_for_destruction? end private # Attribute hash keys that should not be assigned as normal attributes. # These hash keys are nested attributes implementation details. UNASSIGNABLE_KEYS = %w( id _destroy ) # Assigns the given attributes to the association. # # If an associated record does not yet exist, one will be instantiated. If # an associated record already exists, the method's behavior depends on # the value of the update_only option. If update_only is +false+ and the # given attributes include an :id that matches the existing record's # id, then the existing record will be modified. If no :id is provided # it will be replaced with a new record. If update_only is +true+ the existing # record will be modified regardless of whether an :id is provided. # # If the given attributes include a matching :id attribute, or # update_only is true, and a :_destroy key set to a truthy value, # then the existing record will be marked for destruction. def assign_nested_attributes_for_one_to_one_association(association_name, attributes) options = self.nested_attributes_options[association_name] if attributes.respond_to?(:permitted?) attributes = attributes.to_h end attributes = attributes.with_indifferent_access existing_record = send(association_name) if (options[:update_only] || !attributes["id"].blank?) && existing_record && (options[:update_only] || existing_record.id.to_s == attributes["id"].to_s) assign_to_or_mark_for_destruction(existing_record, attributes, options[:allow_destroy]) unless call_reject_if(association_name, attributes) elsif attributes["id"].present? raise_nested_attributes_record_not_found!(association_name, attributes["id"]) elsif !reject_new_record?(association_name, attributes) assignable_attributes = attributes.except(*UNASSIGNABLE_KEYS) if existing_record && existing_record.new_record? existing_record.assign_attributes(assignable_attributes) association(association_name).initialize_attributes(existing_record) else method = "build_#{association_name}" if respond_to?(method) send(method, assignable_attributes) else raise ArgumentError, "Cannot build association `#{association_name}'. Are you trying to build a polymorphic one-to-one association?" end end end end # Assigns the given attributes to the collection association. # # Hashes with an :id value matching an existing associated record # will update that record. Hashes without an :id value will build # a new record for the association. Hashes with a matching :id # value and a :_destroy key set to a truthy value will mark the # matched record for destruction. # # For example: # # assign_nested_attributes_for_collection_association(:people, { # '1' => { id: '1', name: 'Peter' }, # '2' => { name: 'John' }, # '3' => { id: '2', _destroy: true } # }) # # Will update the name of the Person with ID 1, build a new associated # person with the name 'John', and mark the associated Person with ID 2 # for destruction. # # Also accepts an Array of attribute hashes: # # assign_nested_attributes_for_collection_association(:people, [ # { id: '1', name: 'Peter' }, # { name: 'John' }, # { id: '2', _destroy: true } # ]) def assign_nested_attributes_for_collection_association(association_name, attributes_collection) options = self.nested_attributes_options[association_name] if attributes_collection.respond_to?(:permitted?) attributes_collection = attributes_collection.to_h end unless attributes_collection.is_a?(Hash) || attributes_collection.is_a?(Array) raise ArgumentError, "Hash or Array expected, got #{attributes_collection.class.name} (#{attributes_collection.inspect})" end check_record_limit!(options[:limit], attributes_collection) if attributes_collection.is_a? Hash keys = attributes_collection.keys attributes_collection = if keys.include?("id") || keys.include?(:id) [attributes_collection] else attributes_collection.values end end association = association(association_name) existing_records = if association.loaded? association.target else attribute_ids = attributes_collection.map { |a| a["id"] || a[:id] }.compact attribute_ids.empty? ? [] : association.scope.where(association.klass.primary_key => attribute_ids) end attributes_collection.each do |attributes| if attributes.respond_to?(:permitted?) attributes = attributes.to_h end attributes = attributes.with_indifferent_access if attributes["id"].blank? unless reject_new_record?(association_name, attributes) association.build(attributes.except(*UNASSIGNABLE_KEYS)) end elsif existing_record = existing_records.detect { |record| record.id.to_s == attributes["id"].to_s } unless call_reject_if(association_name, attributes) # Make sure we are operating on the actual object which is in the association's # proxy_target array (either by finding it, or adding it if not found) # Take into account that the proxy_target may have changed due to callbacks target_record = association.target.detect { |record| record.id.to_s == attributes["id"].to_s } if target_record existing_record = target_record else association.add_to_target(existing_record, :skip_callbacks) end assign_to_or_mark_for_destruction(existing_record, attributes, options[:allow_destroy]) end else raise_nested_attributes_record_not_found!(association_name, attributes["id"]) end end end # Takes in a limit and checks if the attributes_collection has too many # records. It accepts limit in the form of symbol, proc, or # number-like object (anything that can be compared with an integer). # # Raises TooManyRecords error if the attributes_collection is # larger than the limit. def check_record_limit!(limit, attributes_collection) if limit limit = \ case limit when Symbol send(limit) when Proc limit.call else limit end if limit && attributes_collection.size > limit raise TooManyRecords, "Maximum #{limit} records are allowed. Got #{attributes_collection.size} records instead." end end end # Updates a record with the +attributes+ or marks it for destruction if # +allow_destroy+ is +true+ and has_destroy_flag? returns +true+. def assign_to_or_mark_for_destruction(record, attributes, allow_destroy) record.assign_attributes(attributes.except(*UNASSIGNABLE_KEYS)) record.mark_for_destruction if has_destroy_flag?(attributes) && allow_destroy end # Determines if a hash contains a truthy _destroy key. def has_destroy_flag?(hash) Type::Boolean.new.cast(hash["_destroy"]) end # Determines if a new record should be rejected by checking # has_destroy_flag? or if a :reject_if proc exists for this # association and evaluates to +true+. def reject_new_record?(association_name, attributes) will_be_destroyed?(association_name, attributes) || call_reject_if(association_name, attributes) end # Determines if a record with the particular +attributes+ should be # rejected by calling the reject_if Symbol or Proc (if defined). # The reject_if option is defined by +accepts_nested_attributes_for+. # # Returns false if there is a +destroy_flag+ on the attributes. def call_reject_if(association_name, attributes) return false if will_be_destroyed?(association_name, attributes) case callback = self.nested_attributes_options[association_name][:reject_if] when Symbol method(callback).arity == 0 ? send(callback) : send(callback, attributes) when Proc callback.call(attributes) end end # Only take into account the destroy flag if :allow_destroy is true def will_be_destroyed?(association_name, attributes) allow_destroy?(association_name) && has_destroy_flag?(attributes) end def allow_destroy?(association_name) nested_attributes_options[association_name][:allow_destroy] end def raise_nested_attributes_record_not_found!(association_name, record_id) model = self.class._reflect_on_association(association_name).klass.name raise RecordNotFound.new("Couldn't find #{model} with ID=#{record_id} for #{self.class.name} with ID=#{id}", model, "id", record_id) end end end