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PORails 3: include a field from has_many through association
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  1. PORails 3: include a field from has_many through association
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    copied!<p>My model association is as follows:</p> <pre><code>#book model class Book &lt; ActiveRecord::Base has_many :recommendations, :dependent =&gt; :destroy has_many :similars, :through =&gt; :recommendations, :conditions =&gt; ['recommendation_type IS NULL'], :order =&gt; 'recommendations.created_at DESC' #recommendation model class Recommendation &lt; ActiveRecord::Base belongs_to :book belongs_to :similar, :class_name =&gt; 'Book', :foreign_key =&gt; 'similar_id' #Books_controller - injecting the recommendation_id @book = Book.find(params[:id]) if params[:content_type] @content_type = params[:content_type]; else @content_type = "similars" end case @content_type when "similars" # get the similars @book_content = @book.similars @book_content.each do |similar| @rec_id = Recommendation.where(:book_id=&gt;similar.id, :recommendation_type=&gt;'S').select('id').first.id similar &lt;&lt; {:rec_id =&gt; @rec_id} # ^-- Above line gives NoMethodError (undefined method `&lt;&lt;' for #&lt;Book:0x10de1f40&gt;): end when "references" # get the references @book_content = @book.references @book_content.each do |reference| @rec_id = Recommendation.where(:book_id=&gt;reference.id, :recommendation_type=&gt;'R').select('id').first.id reference &lt;&lt; {:rec_id =&gt; @rec_id} # ^-- Above line gives NoMethodError (undefined method `&lt;&lt;' for #&lt;Book:0x10de1f40&gt;): end end </code></pre> <p>So as noted above, A book has many <em>similars</em> through <em>recommendations</em>. My requirement is that while retrieving <em>similars</em>, I would also like to <strong>include the <em>id</em> of the corresponding record in the join table <em>recommendations</em>.</strong><br> My questions are:</p> <ul> <li><p>How can I include the field *recommendation_id* alongwith <em>similars</em>?</p></li> <li><p>If it cannot be included directly, then what is the correct way to<br> determine this field separately (as shown above) and then inject it into the <em>similars</em> instance variable so that I can use it directly in my views?</p></li> </ul>
 

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