title: Extjs 4 - Combining two grid columns
body: <p>I have a datastore and a grid. I am trying to declare a new column called FullName that would combine the two dataindexes. After spending some time researching this issue, I understand it could either be a renderer  (grid level) or it could be a custom column in the datastore (mapping?). </p>
  
  <p>Can someone provide a code sample that implements such a column?</p>
  
  <pre><code>// XML
  &lt;person&gt;
      &lt;first_name&gt;John&lt;/first_name&gt;
      &lt;last_name&gt;Smith&lt;/last_name&gt;
  &lt;/person&gt; 
  
  // Store
  Ext.create('Ext.data.Store', {
      autoLoad: true,
      storeId: 'TestStore',
      fields: ['first_name', 'last_name'],
      data: parsed_xml_object,
      proxy: {
          type: 'memory',
          reader: {
              type: 'xml',
              record: 'person'
          }
      }
  });
  
  // Grid
  TestGrid = Ext.create('Ext.grid.Panel', {
      title: 'Test',
      store: Ext.data.StoreManager.lookup('TestStore'),
      columns: [
          { header: 'First Name', dataIndex: 'first_name' },
          { header: 'Last Name Name', dataIndex: 'last_name' },
       ],
      height: 200,
      autowidth: true
  });
  </code></pre>