title: laravel call to undefined method addEagerConstraints()
body: <p>I have two models </p>
  
  <p>Post.php</p>
  
  <blockquote>
    <p>id</p>
    
    <p>post</p>
    
    <p>show_id </p>
    
    <p>type = 'movie' or 'tv'</p>
  </blockquote>
  
  <p>Show.php</p>
  
  <blockquote>
    <p>id // this only auto increment counter ids<br>
    show_id</p>
    
    <p>show_type = 'movie' or 'tv'</p>
  </blockquote>
  
  <p>the thing is show can be either tv or movie and may two with the same show_id for exmaple one tv could have a show_id of 10 and also one movie can have it but the types are diffrent</p>
  
  <p>i have in post model</p>
  
  <pre><code>public function show(){
        return $this-&gt;belongsTo('App\Show', 'show_id');
      }
  </code></pre>
  
  <p>in show model </p>
  
  <pre><code>public function post(){
    return $this-&gt;hasMany('App\Post', 'id');
  }
  </code></pre>
  
  <p>this relationship get the first show with matching show id it sees, wheather its a movie or tv, i want to restrict it to match type column on both sides</p>