title: Laravel firstOrNew with multiple conditions?
body: <p>I have a model called <code>Stock</code> and I want to insert or update a row (if its already exists).
  The table has 6 columns:</p>
  
  <pre><code>drink_id
  flow_id
  bought
  left
  created_at
  updated_at
  </code></pre>
  
  <p>With jQuery I collect the data, pass it through with ajax. The data arrives but the following code does not work properly:</p>
  
  <pre><code>$row = Stock::firstOrNew(array( 'drink_id'  =&gt; $drink_id,
                  'flow_id'   =&gt; $max_flow));
  
  
  $row -&gt; bought = $bought;
  $row -&gt; left = $left;
  $row -&gt; save();
  </code></pre>
  
  <p>I got the following error:</p>
  
  <pre><code>{"error":
     {
      "type":"Illuminate\\Database\\QueryException",
      "message":"SQLSTATE[42S22]: Column not found: 1054 Unknown column 'id'
          in 'where clause' (SQL: update `stock` set `bought` = 22,
          `updated_at` = 2014- 05-18 09:10:14 where `id` is null)",
          "file":"C:\\wamp\\www\\csabi\\vendor\\laravel\\framework\\src\\Illuminate\\Database\\Connection.php",
          "line":539
     }
  }
  </code></pre>