title: array_unique showing error Array to string conversion
body: <p>For getting the unique values i am using unique values. Below is the code i am using</p>
  
  <pre><code>array_unique($results_external);
  aasort($results_external,"created_on");
  $returns_buy_external[]=array_reverse($results_external, true);
  </code></pre>
  
  <p>If i use the code like this, below is the error i am getting</p>
  
  <blockquote>
    <p>A PHP Error was encountered Severity: Notice</p>
    
    <p>Message: Array to string conversion</p>
    
    <p>Filename: models/product_model.php</p>
    
    <p>Line Number: 3550</p>
  </blockquote>
  
  <p>3550 line is array_unique($results_external);</p>
  
  <p>Can anyone help me, why it is getting error like this and how to solve it?</p>
  
  <p>results_external sample format coming is below</p>
  
  <pre><code>Array
  (
      [0] =&gt; Array
          (
              [id] =&gt; 144
              [name] =&gt; test
              [slug] =&gt; test
              [images] =&gt; {"9eebd0f69772dd3bdf8c787864437c85":{"filename":"9eebd0f69772dd3bdf8c787864437c85.png","alt":"TRESemme Smooth and Shine","caption":""}}
              [track_stock] =&gt; 1
              [seo_title] =&gt; ttt
              [qty] =&gt; 0
              [product_type] =&gt; 0
              [price] =&gt; 0.00
              [saleprice] =&gt; 0.00
              [external_links] =&gt; http://test.com
              [external_price] =&gt; 285.00
              [external_saleprice] =&gt; 285.00
              [created_on] =&gt; 2013-11-08 15:03:24
          )
  )
  </code></pre>