title: extjs 4.2 how to create a queryplan
body: <p><a href="http://docs.sencha.com/extjs/4.2.1/#!/api/Ext.form.field.ComboBox" rel="nofollow">http://docs.sencha.com/extjs/4.2.1/#!/api/Ext.form.field.ComboBox</a>
  has a beforeQuery event. But when I try this I get a complaint that there is no queryplan.</p>
  
  <p>How can this be established? I can find no documentation anywhere in how to set up a queryplan.</p>
  
  <pre><code>                                {
                                      xtype: 'combo',
                                      flex: 2,
                                      fieldLabel: 'other',
                                      displayField: 'city_name',
                                      name: 'city_name',
                                      itemId:'city_name',
                                      emptyText: 'plaats',
                                      store:{
                                          type: 'location.city'
                                      },
  
                                     beforeQuery: function( queryEvent, eOpts ){
                                          var me = this;
  
                                          var store = me.getStore();
  
                                          store.proxy.extraParams={
                                              fieldName: 'city.name',
                                              fieldValue: me.getValue()
                                          };
  
                                          // return true;
                                      }, ...
  </code></pre>