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diff --git a/railties/guides/source/nested_model_forms.textile b/railties/guides/source/nested_model_forms.textile deleted file mode 100644 index 4b1fd2e0ac..0000000000 --- a/railties/guides/source/nested_model_forms.textile +++ /dev/null @@ -1,222 +0,0 @@ -h2. Rails nested model forms - -Creating a form for a model _and_ its associations can become quite tedious. Therefore Rails provides helpers to assist in dealing with the complexities of generating these forms _and_ the required CRUD operations to create, update, and destroy associations. - -In this guide you will: - -* do stuff - -endprologue. - -NOTE: This guide assumes the user knows how to use the "Rails form helpers":form_helpers.html in general. Also, it’s *not* an API reference. For a complete reference please visit "the Rails API documentation":http://api.rubyonrails.org/. - - -h3. Model setup - -To be able to use the nested model functionality in your forms, the model will need to support some basic operations. - -First of all, it needs to define a writer method for the attribute that corresponds to the association you are building a nested model form for. The +fields_for+ form helper will look for this method to decide whether or not a nested model form should be build. - -If the associated object is an array a form builder will be yielded for each object, else only a single form builder will be yielded. - -Consider a Person model with an associated Address. When asked to yield a nested FormBuilder for the +:address+ attribute, the +fields_for+ form helper will look for a method on the Person instance named +address_attributes=+. - -h4. ActiveRecord::Base model - -For an ActiveRecord::Base model and association this writer method is commonly defined with the +accepts_nested_attributes_for+ class method: - -h5. has_one - -<ruby> -class Person < ActiveRecord::Base - has_one :address - accepts_nested_attributes_for :address -end -</ruby> - -h5. belongs_to - -<ruby> -class Person < ActiveRecord::Base - belongs_to :firm - accepts_nested_attributes_for :firm -end -</ruby> - -h5. has_many / has_and_belongs_to_many - -<ruby> -class Person < ActiveRecord::Base - has_many :projects - accepts_nested_attributes_for :projects -end -</ruby> - -h4. Custom model - -As you might have inflected from this explanation, you _don’t_ necessarily need an ActiveRecord::Base model to use this functionality. The following examples are sufficient to enable the nested model form behaviour: - -h5. Single associated object - -<ruby> -class Person - def address - Address.new - end - - def address_attributes=(attributes) - # ... - end -end -</ruby> - -h5. Association collection - -<ruby> -class Person - def projects - [Project.new, Project.new] - end - - def projects_attributes=(attributes) - # ... - end -end -</ruby> - -NOTE: See (TODO) in the advanced section for more information on how to deal with the CRUD operations in your custom model. - -h3. Views - -h4. Controller code - -A nested model form will _only_ be built if the associated object(s) exist. This means that for a new model instance you would probably want to build the associated object(s) first. - -Consider the following typical RESTful controller which will prepare a new Person instance and its +address+ and +projects+ associations before rendering the +new+ template: - -<ruby> -class PeopleController < ActionController:Base - def new - @person = Person.new - @person.built_address - 2.times { @person.projects.build } - end - - def create - @person = Person.new(params[:person]) - if @person.save - # ... - end - end -end -</ruby> - -NOTE: Obviously the instantiation of the associated object(s) can become tedious and not DRY, so you might want to move that into the model itself. ActiveRecord::Base provides an +after_initialize+ callback which is a good way to refactor this. - -h4. Form code - -Now that you have a model instance, with the appropriate methods and associated object(s), you can start building the nested model form. - -h5. Standard form - -Start out with a regular RESTful form: - -<erb> -<%= form_for @person do |f| %> - <%= f.text_field :name %> -<% end %> -</erb> - -This will generate the following html: - -<html> -<form action="/people" class="new_person" id="new_person" method="post"> - <input id="person_name" name="person[name]" size="30" type="text" /> -</form> -</html> - -h5. Nested form for a single associated object - -Now add a nested form for the +address+ association: - -<erb> -<%= form_for @person do |f| %> - <%= f.text_field :name %> - - <%= f.fields_for :address do |af| %> - <%= af.text_field :street %> - <% end %> -<% end %> -</erb> - -This generates: - -<html> -<form action="/people" class="new_person" id="new_person" method="post"> - <input id="person_name" name="person[name]" size="30" type="text" /> - - <input id="person_address_attributes_street" name="person[address_attributes][street]" size="30" type="text" /> -</form> -</html> - -Notice that +fields_for+ recognized the +address+ as an association for which a nested model form should be built by the way it has namespaced the +name+ attribute. - -When this form is posted the Rails parameter parser will construct a hash like the following: - -<ruby> -{ - "person" => { - "name" => "Eloy Duran", - "address_attributes" => { - "street" => "Nieuwe Prinsengracht" - } - } -} -</ruby> - -That’s it. The controller will simply pass this hash on to the model from the +create+ action. The model will then handle building the +address+ association for you and automatically save it when the parent (+person+) is saved. - -h5. Nested form for a collection of associated objects - -The form code for an association collection is pretty similar to that of a single associated object: - -<erb> -<%= form_for @person do |f| %> - <%= f.text_field :name %> - - <%= f.fields_for :projects do |pf| %> - <%= pf.text_field :name %> - <% end %> -<% end %> -</erb> - -Which generates: - -<html> -<form action="/people" class="new_person" id="new_person" method="post"> - <input id="person_name" name="person[name]" size="30" type="text" /> - - <input id="person_projects_attributes_0_name" name="person[projects_attributes][0][name]" size="30" type="text" /> - <input id="person_projects_attributes_1_name" name="person[projects_attributes][1][name]" size="30" type="text" /> -</form> -</html> - -As you can see it has generated 2 +project name+ inputs, one for each new +project+ that was built in the controller's +new+ action. Only this time the +name+ attribute of the input contains a digit as an extra namespace. This will be parsed by the Rails parameter parser as: - -<ruby> -{ - "person" => { - "name" => "Eloy Duran", - "projects_attributes" => { - "0" => { "name" => "Project 1" }, - "1" => { "name" => "Project 2" } - } - } -} -</ruby> - -You can basically see the +projects_attributes+ hash as an array of attribute hashes, one for each model instance. - -NOTE: The reason that +fields_for+ constructed a form which would result in a hash instead of an array is that it won't work for any forms nested deeper than one level deep. - -TIP: You _can_ however pass an array to the writer method generated by +accepts_nested_attributes_for+ if you're using plain Ruby or some other API access. See (TODO) for more info and example. |