title: Rails Form not saving the Association Attributes
body: <p>For some reason, the form seems to work as intended but it does not process correctly:</p>
  
  <p>Here are the parameters that are sent to my Paragraph#create method</p>
  
  <p><code>Parameters: {"utf8"=&gt;"✓", "authenticity_token"=&gt;"s6V7WS6NZwcu4ZAeSenkEgVEd6MrrDD1asMjPEOuZHyglMKoGQ/5cP/USzF/5MJV3wyFn+siC2t47dSFkVtuVQ==", "paragraph"=&gt;{"sentiments_attributes"=&gt;{"0"=&gt;{"body"=&gt;"test"}}}}</code></p>
  
  <p>I get this error when trying to submit the form: <code>Sentiments body can't be blank</code></p>
  
  <pre><code> #paragraphs_controller.rb
    def create
      @paragraph = Paragraph.new(paragraph_params)
      @paragraph.sentiments.build
      if @paragraph.save
        redirect_to root_url
      else
        puts @paragraph.errors.full_messages
        redirect_to root_url
      end
    end
  
    private
    def paragraph_params
      params.require(:paragraph).permit(:sentiments_attributes =&gt; [:body])
    end
  </code></pre>
  
  <p>I have 2 models, Sentiment &amp; Paragraph. The Paragraph is a collection of sentiments. So if I have a form to create a new paragraph, it creates a sentiment at the same time.</p>
  
  <pre><code>class Sentiment &lt; ApplicationRecord
    belongs_to :paragraph, optional: true
    validates :body, presence: true
  
  end
  class Paragraph &lt; ApplicationRecord
    has_many :sentiments
    accepts_nested_attributes_for :sentiments
  
  end
  
  &lt;%= form_for(@paragraph) do |f| %&gt;
    &lt;%= f.fields_for :sentiments do |u| %&gt;
          &lt;%= u.text_area :body %&gt;
    &lt;% end  %&gt;
    &lt;%= f.submit %&gt;
  &lt;% end %&gt;
  </code></pre>
  
  <p><strong>UPDATED</strong></p>
  
  <p>Need to remove <code>@paragraph.sentiments.build</code> from <code>paragraphs_controller#create</code></p>