Ext.override(Ext.form.ComboBox, {
     setValue: function(v, fireSelect) {
         var text = v;
         if (this.valueField) {
             var r = this.findRecord(this.valueField, v);
             if (r) {
                 text = r.data[this.displayField];
                 if (fireSelect) {
                     this.fireEvent('select', this, r, this.store.indexOf(r));
                 }
             } else if (Ext.isDefined(this.valueNotFoundText)) {
                 text = this.valueNotFoundText;
             }
         }
         this.lastSelectionText = text;
         if (this.hiddenField) {
             this.hiddenField.value = v;
         }
         Ext.form.ComboBox.superclass.setValue.call(this, text);
         this.value = v;
         return this;
     }
 });

擴(kuò)展的作者為Animal

調(diào)用setValue方法的同時，fireEvent（"select",...），觸發(fā)combo的select事件

重寫后的方法有兩個參數(shù)
v：combo的valueField值，比如combo的fields: [{ name: 'CATEGORYID' }, { name: 'TITLE'}]
傳進(jìn)來的參數(shù)應(yīng)該為CATEGORYID的某一個值，而不是TITLE的某一個值。。。
fireSelect：bool類型的，即是否對setValue觸發(fā)select事件