title: Json Parsing in ExtJs 4
body: <p>I am new to ExtJs 4.I am using Json to populate combo box,as follows,</p>
  
  <p><strong>JSON:</strong></p>
  
  <pre><code>{
     "Patient": [
        {
           "id": 1,
           "emergencyPhone": "1234567890",
           "primaryInsuranceId": {
              "id": 1
           },
           "secondaryInsuranceId": {
              "id": 2
           },
           "personalInfo": {
              "id": 2,
              "firstName": "James",
              "lastName": "Anderson",
              "address": {
                 "state": {
                    "id": "2",
                    "stateName": "Alaska",
                    "code": "AK"
                 },
                 "zipcode": 12345,
                 "country": "USA",
                 "telephone": "1234567890",
                 "alternatePhone": "1234567890",
                 "faxNumber": "1234567890",
                 "email": "james@gmail.com"
              },
              "gender": "Male",
              "dob": "2012-04-02",
              "ssn": 123456789,
              "race": "race"
           },
           "clearinghouseId": {
              "id": 2,
              "name": "ALPHA Clearing House"
           },
           "provider": []
        }
     ]
  }
  </code></pre>
  
  <p><strong>Code:</strong></p>
  
  <pre><code>Ext.define('patientList', {
      extend: 'Ext.data.Model',
      fields: ['id', 'personalInfo']
  });
  
  var patient = Ext.create('Ext.data.Store', {
      model: 'patientList',
      autoLoad: true,
      proxy: {
          type: 'ajax',
          url: url + '/lochweb/loch/patient/getAll',
          reader: {
              type: 'json',
              root: 'Patient'
          }
      }
  });
  </code></pre>
  
  <p><strong>Combo Box</strong></p>
  
  <pre><code>{
      xtype: 'combo',
      fieldLabel: 'Patient',
      name: "patientId",
      id: "patientId",
      queryMode: 'local',
      store: patient,
      displayField: 'personalInfo.firstName',
      valueField: 'id',
      emptyText: "Select",
      editable: false,
      allowBlank: false
  }
  </code></pre>
  
  <p>When i click the combo box,it shows firstname but after selecting that,it is not displaying in drop down.Any Help</p>
  
  <p>Thanks</p>