title: PHP json_encode not working with array of objects
body: <p>I am developing php application in which i am querying database and the generated result I am sending back to html client.</p>
  
  <p>Currently I am getting array of objects which I am encoding in JSON using php function json_encode.</p>
  
  <p>But after encoding I am getting null array in my result.</p>
  
  <p>The following structure is before encoding to JSON</p>
  
  <pre><code> array(2) {
    [0]=&gt;   
        object(ProductComment)#6 (2) {
      ["_productId":"ProductComment":private]=&gt;
      string(1) "1"
      ["_commentArray":"ProductComment":private]=&gt;
      array(2) {
        [0]=&gt;
        array(3) {
          ["comment"]=&gt;
          string(9) "comment 1"
          ["creationDate"]=&gt;
          string(19) "2000-02-02 00:00:00"
          ["userName"]=&gt;
          string(8) "Ashutosh"
        }
        [1]=&gt;
        array(3) {
          ["comment"]=&gt;
          string(13) "comment1 text"
          ["creationDate"]=&gt;
          string(19) "2012-07-31 10:20:27"
          ["userName"]=&gt;
          string(8) "Ashutosh"
        }
      }
    }
    [1]=&gt;
    object(ProductComment)#5 (2) {
      ["_productId":"ProductComment":private]=&gt;
      string(1) "2"
      ["_commentArray":"ProductComment":private]=&gt;
      array(2) {
        [0]=&gt;
        array(3) {
          ["comment"]=&gt;
          string(22) "comment2 product2 text"
          ["creationDate"]=&gt;
          string(19) "2012-07-31 10:48:06"
          ["userName"]=&gt;
          string(8) "Ashutosh"
        }
        [1]=&gt;
        array(3) {
          ["comment"]=&gt;
          string(22) "comment2 product4 text"
          ["creationDate"]=&gt;
          string(19) "2012-07-31 10:48:14"
          ["userName"]=&gt;
          string(8) "Ashutosh"
        }
      }
    }
  }
  </code></pre>
  
  <p>And after encoding it showing null instead of JSON.
  Do i need to serialize it?
  Anything advice will be appreciable.
  Thanking you.</p>