title: Extjs: How to set extraparam from controller to use in the store for populating combobox value.want to set extraparam value as abc.1-cond1, abc.2-con2
body: <p>In ExtJS I want to set extraParam in a controller.
  These extraParams should be used in a store.</p>
  <p>I want to show data in my combobox based on a condition.</p>
  <p>If condition 1 is satisfied the extraparam contains <code>abc.1</code></p>
  <p>Then the store loads data corresponding to a groupID to get data</p>
  <p>..same for condition 2(abc.2).</p>
  <p>how can i set extraparam?</p>
  <p>//Store</p>
  <pre><code>abcStore: {
      type: 'store',
      proxy: {
          type: 'ajax',
          url: PPA_SERVICE_BASE_URL + 'any.Service',
          paramsAsJson: true,
          actionMethods: {
              read: 'POST'
          },
          reader: {
              type: 'json',
              rootProperty: 'data'
          },                       
      }
  }
     
  </code></pre>
  <p>//Combobox</p>
  <pre><code>xtype: 'combobox',
  fieldLabel: 'Payment Stream Type',
  labelWidth: 130,
  width: 280,
  editable: false,
  margin: '0 10 0 0',
  displayField: 'label',
  allowBlank: false,
  bind: {
      store: '{abcStore}',
  }
  </code></pre>
  <p>//Controller - function to load data</p>
  <pre><code>loadabcData: function(newValue) {
      var me = this,
          view = me.getView(),
          viewModel = this.getViewModel(),
          store = viewModel.getStore('abcStore'),
          extraParam = {groupId: groupId};
  
      store.getProxy().setExtraParams(extraParams);
      store.load();
        
      // How should i further set this groupID.I want to set groupId value as abc.1 on condition1 and //abc.2 on condition 2
  },
  </code></pre>