title: Not able to load Extjs Grid by json data
body: <p>Simple grid showing three columns ... 
  trying to get a json data 
  Trying to display 3 columns Subject Id , Subject Name and Subject Short Name ..
  in myData a json format data is saved.
  i have just pasted the data received from server for myData.
  I dont understand why data is not displaying.</p>
  
  <pre><code>var myData = {"subjectStoreRoot":[{"subjectName":"Chemistry","subjectId":"Chem01","subjectShortName":"Chemistry"},{"subjectName":"Mathematics","subjectId":"Math01","subjectShortName":"Maths"},{"subjectName":"English","subjectId":"Eng01","subjectShortName":"Eng"},{"subjectName":"Science","subjectId":"Sci01","subjectShortName":"Sci"},{"subjectName":"Social Studies","subjectId":"SS01","subjectShortName":"Social"},{"subjectName":"Kannada","subjectId":"Kan01","subjectShortName":"Kan"}]};
  
  store =  new Ext.data.ArrayStore({
  
  
  data:Ext.decode(myData),
                                          //  
  autoDestroy : true,
  
  
      autoLoad:true,
  
      storeId: 'subjectsGridStoreId',
  
      // reader configs
  
      root: 'subjectStoreRoot',
                                              //  
      idProperty: 'subjectId',
  
      fields: [
  
      {name: 'subjectId' ,type:'string'},
  
      {name: 'subjectName' ,type:'string'},
  
      {name: 'subjectShortName' ,type:'string'}
  
  
                                                  ]
                                              });
  
      grid = new Ext.grid.GridPanel({
                                                      store: store,
                                                      stripeRows:true,
                                                      scrollable:true,
                                                      columnLines:true,
                                                      columns: [
                                                          {
                                                              id       :'subjectId',
                                                              header   : 'Subject Id', 
                                                              width    : 250, 
                                                              sortable : true, 
                                                              dataIndex: 'subjectId'
                                                          },{
                                                              id       :'subjectName',
                                                              header   : 'Subject Name', 
                                                              width    : 250, 
                                                              sortable : true, 
                                                              dataIndex: 'subjectName'
                                                          },{
                                                              id       :'subjectShortName',
                                                              header   : 'Subject Short Name', 
                                                              width    : 250, 
                                                              sortable : true, 
                                                              dataIndex: 'subjectShortName'
                                                          }
                                                      ],
                                                   //   autoExpandColumn: 'subjectName',
                                                      height: 300,
                                                  //  width: 350,
                                                      autoScroll:true,
                                                      title: 'List of all Subjects',
                                                      // config options for stateful behavior
                                                      stateful: true,
                                                      stateId: 'grid'
                                                  });
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/a9uq6.png" alt="enter image description here"></p>
  
  <p>As 
  Please guide why the data is not displaying on the grid?</p>