title: Set the value of an ExtJS ComboBox to an Object, not an object property
body: <p>I have a ComboBox in an EditorGrid. I am populating it (trying) using JSON, which is produced by serializing an <code>IList&lt;FertilizerType&gt;</code>. <strong>I want the valueField of the ComboBox to be equal to the <code>FertilizerType</code> objects and the displayField equal to <code>FertilizerType.Name</code></strong></p>
  
  <p>Here is a <code>Crop</code>:</p>
  
  <pre><code>{\"Id\":1300,\"Active\":true,\"Code\":\"Ammonium Bicarbonate\",\"Description\":\"Ammonium Bicarbonate\",\"GroupName\":\"FertilizerType\",\"Name\":\"Ammonium Bicarbonate\",\"Ordinal\":1}
  </code></pre>
  
  <p>Why do I want to set the valueField to an object you might ask? Well, all the data in the grid is part of a <code>Crop</code> object. The ComboBox needs to return a <code>FertilizerType</code> so that <code>Crop.FertilizerType</code> can be populated.</p>
  
  <p>Here is my Column definition:</p>
  
  <pre><code>{
              header: 'Fertilizer Type',
              dataIndex: 'FertilizerType',
              width: 170,
              editor: new Ext.form.ComboBox({
                  store: new Ext.data.Store({
                      proxy: new Ext.data.HttpProxy({
                          url: Cbp.baseUrl + 'Controller/GetFertilizerTypes'
                      }),
                      reader: new Ext.data.JsonReader({}, ['FertilizerType', 'FertilizerType.Name']),
                      remoteSort: false
                  }),
                  valueField: 'FertilizerType',
                  displayField: 'FertilizerType.Name',
                  hiddenName: 'FertTypeObject',
                  mode: 'remote',
                  minChars: 0
              })
          }
  </code></pre>
  
  <p>Thanks for any help! This is driving me nuts!</p>