title: Cakephp 3: belongsToMany contain or matching condition?
body: <p>Piece of my database looks like <a href="http://i.stack.imgur.com/4eMdI.jpg" rel="nofollow">database part</a></p>
  
  <p>Categories use tree behavior.</p>
  
  <p>How can i get a manufacturer's (Producers) Products for current Category? 
  I tried contain and matching, but i received duplicated data or Producers names without related Products.</p>
  
  <p>EDIT:</p>
  
  <pre><code>$query = $this-&gt;Producers-&gt;find()-&gt;matching('Products.Categories',
      function ($q) {
          return $q-&gt;where(['Categories.id' =&gt; 18]); 
      }
  );
  </code></pre>
  
  <p>Results:</p>
  
  <pre><code>Producent: Canon
  -------------------------------------------
  | ID | Name        | Barcode              |
  -------------------------------------------
  | 1  | EOS 1000D   |                      |
  -------------------------------------------
  | 18 | Camera      |                      |
  -------------------------------------------
  | 23 | 18          |                      |
  -------------------------------------------
  </code></pre>
  
  <p>First row (id = 1) it's what i need.
  Now i have to remove from results:
  second row (id = 18) this is Category id from table Categories, 
  thrid row (id = 23) - from Products_Categories table. </p>