More Complex Many to Many

I didn't pick the best example for this video (artists and tracks), but if you imagine that songs can be covered by many artists (think "Mack the Knife" or something), it works:

<span class="hljs-keyword">class</span> <span class="hljs-title class_">Artist</span> &lt; <span class="hljs-title class_ inherited__">ApplicationRecord</span>
  has_many <span class="hljs-symbol">:albums</span>
  has_many <span class="hljs-symbol">:tracks</span>, <span class="hljs-symbol">through:</span> <span class="hljs-symbol">:albums</span>
<span class="hljs-keyword">end</span>

The other end of the association needs to link back:

<span class="hljs-keyword">class</span> <span class="hljs-title class_">Track</span> &lt; <span class="hljs-title class_ inherited__">ApplicationRecord</span>
  belongs_to <span class="hljs-symbol">:album</span>
  belongs_to <span class="hljs-symbol">:media_type</span>
  belongs_to <span class="hljs-symbol">:genre</span>
  has_and_belongs_to_many <span class="hljs-symbol">:playlists</span>
  has_many <span class="hljs-symbol">:artists</span>, <span class="hljs-symbol">through:</span> <span class="hljs-symbol">:album</span>
<span class="hljs-keyword">end</span>