title: Rails Has Many Through Controller
body: <p>At the moment I have three models</p>
  
  <pre><code>A Song has many setlists through Allocations
  Allocations belong to Songs and belong to setlists
  A setlist has many Songs through Allocations.
  </code></pre>
  
  <p>Once I've created a list the data is displayed in a table with the following link:</p>
  
  <pre><code>&lt;td&gt;&lt;%= link_to setlist.date, '#' %&gt;&lt;/td&gt;
  </code></pre>
  
  <p>I basically want to have it so that when you click this link, it leads the user to a page where you can select existing songs from the database and add them to the performance list. I'm not entirely sure where to begin as I haven't had much experience with using has many through relationships, so any pointer in the right direction would be helpful. What should I replace the '#' with? Would it be to a new_allocation_path? Or is there any way of using a nested form so that I can add the songs to the setlists as I create them in the first place? </p>