title: jqGrid tree grid - not showing?
body: <p>There is a concept that eludes me ... I can't figure out what is it I do wrong !!! 
  I have the following JSON:</p>
  
  <pre><code>{
   "data":[
    {
       "amount":150.00,
       "dealDate":"10/18/15 11:53 AM",
       "dealName":"Deal 1",
       "id":"1",
       "parent":"null", 
       "level":"0", 
       "isLeaf":false, 
       "loaded":true        
    },
    {
       "amount":100.00,
       "dealDate":"10/16/15 11:53 AM",
       "dealName":"Deal 1a",
       "id":"2",
       "parent":"1", 
       "level":"1", 
       "isLeaf":true, 
       "loaded":true        
    },
    {
       "amount":-20.34,
       "dealDate":"10/16/15 11:53 AM",
       "dealName":"Deal 1b",
       "id":"3",
       "parent":"1", 
       "level":"1", 
       "isLeaf":true, 
       "loaded":true 
    },
    {
       "amount":25,
       "dealDate":"10/16/15 11:53 AM",
       "dealName":"Deal 2",
       "id":"4",
       "parent":"null", 
       "level":"0", 
       "isLeaf":false, 
       "loaded":true           
    }
   ]
  }
  </code></pre>
  
  <p>And the jQgrid definition: (with the treeGrid options removed (commented out))</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
    $(function () {
  
      var mydata ;
          $.getJSON( "sampleData.json", function( data ) {
            mydata=$.extend(true, [], data.data) ;
  
      console.log("Initial JSON data:\n" + JSON.stringify(mydata));
  
           $("#list").jqGrid({
           data: mydata,           
           datatype: "local",
           mtype: "GET",
           colNames: ["id", "Title", "Amount", "Date", "","","",""],
           colModel: [                    
               { name: "id", width: 55, hidden: true},                 
               { name: "dealName", width: 90, editable: true },
               { name: "amount", width: 80, align: "right",editable: true },
               { name: "dealDate", width: 80, align: "right", editable: true }
              { name: "parent", width: 80, align: "right", hidden: true },
              { name: "level", width: 80, align: "right", hidden: true },
               { name: "isLeaf", width: 80, align: "right", hidden: true },
               { name: "loaded", width: 80, align: "right", hidden: true }
           ],
           editurl: 'clientArray',
           cellsubmit : 'clientArray',             
           rowNum: 10,
           rowList: [10, 20, 30, 50],
           sortname: "id",
           viewrecords: true,
           gridview: true,
   //              treeGrid: true,
   //              ExpandColumn: 'dealName',
   //              treeGridModel:'adjacency',                  
           width: $(window).width() *0.55,
           caption: "Deal Test Grid"      
       });
      $("#list").jqGrid('navGrid', "#pager", { edit: false, add: false, del:   
       false });
       $("#list").jqGrid('gridResize');
        });
    }); 
   &lt;/script&gt;
  </code></pre>
  
  <p>And this produces perfectly fine grid !!
  <a href="https://i.stack.imgur.com/79Uh7.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/79Uh7.jpg" alt="enter image description here"></a>
  HOWEVER !!! 
  Once I remove comments from tree grid parameters, my grid is NOT loaded !!
  <a href="https://i.stack.imgur.com/5uIiH.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/5uIiH.jpg" alt="enter image description here"></a></p>
  
  <p>I have tried with adding and with removing of quotes around null value of a parent where there is no parent</p>
  
  <pre><code>         "parent":"null", vs.          "parent":null,  
  </code></pre>
  
  <p>No avail !! Same results !!
  Please, help !! What is it called - that thing that I am doing wrong.  </p>