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PORails nested form with nested resource: update belongs_to association when creating new has_many
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  1. PORails nested form with nested resource: update belongs_to association when creating new has_many
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    copied!<p>Hey guys, I've been beating my head against a wall with a particular use case for nested forms (I'm using Rails 2.3.5).</p> <p>Essentially I have Project and Payment models that looks like this</p> <pre><code>class Project &lt; ActiveRecord::Base has_many :payments end class Payment &lt; ActiveRecord::Base belongs_to :project accepts_nested_attributes_for :project end </code></pre> <p>I'm also using nested routing for these two resources:</p> <pre><code>map.resources :projects do |project| project.resources :payments end </code></pre> <p>I'm trying to use a nested form to allow the user to modify certain attributes of the Project when creating a new Payment. So if the Project has a title, for example, the view for creating a new Payment would look like this:</p> <pre><code>&lt;% form_for([@project, @payment]) do |f| %&gt; &lt;% f.fields_for :project do |project_form| %&gt; &lt;%= project_form.label :title %&gt; &lt;%= project_form.text_field :title %&gt; &lt;% end %&gt; &lt;%= f.text_field :credit_card_number %&gt; ... &lt;% end %&gt; </code></pre> <p>The Payments controller is pretty much standard:</p> <pre><code>class PaymentsController &lt; ApplicationController before_filter :load_project # GET /payments/new # GET /payments/new.xml def new @payment = @project.payments.build respond_to do |format| format.html # new.html.erb format.xml { render :xml =&gt; @payment } end end # POST /payments # POST /payments.xml def create @payment = @project.payments.build(params[:payment]) respond_to do |format| if @payment.save flash[:notice] = 'Payment was successfully created.' format.html { redirect_to([@project, @payment]) } format.xml { render :xml =&gt; @payment, :status =&gt; :created, :location =&gt; @payment } else format.html { render :action =&gt; "new" } format.xml { render :xml =&gt; @payment.errors, :status =&gt; :unprocessable_entity } end end end private def load_project @project = Project.find(params[:project_id]) end end </code></pre> <p>What I'm finding is that on the new Payment form, I'm ending up with something like this:</p> <pre><code>&lt;input id="payment_project_attributes_title" name="payment[project_attributes][title]" size="30" type="text" /&gt; &lt;input id="payment_project_attributes_id" name="payment[project_attributes][id]" type="hidden" value="56" /&gt; </code></pre> <p>(Note the automatically created #payment_project_attributes_id)</p> <p>When the form is submitted, rails receives this like so (bear in mind that Project #56 already exists):</p> <pre><code>"payment"=&gt;{"project_attributes"=&gt;{"title"=&gt;"test title", "id"=&gt;"56"}, "credit_card_number"=&gt;"41111111111111111"} </code></pre> <p>And here's the problem: when this is run through the controller, it DOESN'T apply the title attribute to the Payment's Project.</p> <p>What's strange is that if I remove that <strong>"id"=>"56"</strong>, the Project's title IS updated. Here's an example using the console:</p> <pre><code>ruby-1.8.7-p249 &gt; Project.find(56) =&gt; #&lt;Project id: 56, title: nil, created_at: "2010-06-18 15:58:25", updated_at: "2010-06-18 16:01:37"&gt; ruby-1.8.7-p249 &gt; p=Project.find(56).payments.new({"project_attributes"=&gt;{"title"=&gt;"my new title", "id"=&gt;"56"}}) =&gt; #&lt;Payment id: nil, project_id: 56, created_at: nil, updated_at: nil&gt; ruby-1.8.7-p249 &gt; p.project =&gt; #&lt;Project id: 56, title: nil, created_at: "2010-06-18 15:58:25", updated_at: "2010-06-18 16:01:37"&gt; ruby-1.8.7-p249 &gt; p=Project.find(56).payments.new({"project_attributes"=&gt;{"title"=&gt;"test title"}}) =&gt; #&lt;Payment id: nil, project_id: 56, created_at: nil, updated_at: nil&gt; ruby-1.8.7-p249 &gt; p.project =&gt; #&lt;Project id: nil, user_id: nil, title: "test title", created_at: nil, updated_at: nil&gt; </code></pre> <p>(Note that the second payments.new, without the ID, causes p.project.title to be updated)</p> <p>This seems directly contradictory to this ticket: <a href="https://rails.lighthouseapp.com/projects/8994/tickets/3687-nested-attributes-with-belongs_to-only-supports-one-use-case" rel="nofollow noreferrer">https://rails.lighthouseapp.com/projects/8994/tickets/3687-nested-attributes-with-belongs_to-only-supports-one-use-case</a></p> <p>Does anybody have any thoughts?</p> <p>I should note that what I'm really trying to do is one layer more complex--I'm trying to update user_attributes for Project (using a belongs_to :user/accepts_nested_attributes_for :user on the Project) but I'm sort of hoping that will just <em>work</em> if I can figure this out.</p>
 

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