构造extjs两级联动comBox 子曰

 

 {
                columnWidth: .25,
                layout: "form",
                items: [{
                    xtype: 'combo',
                    fieldLabel: "区域",
                    editable: false,
                    //是否允许输入 

                       hiddenName: 'quyu',
                    store: areaStore,
                    mode: 'remote',//第一个combo为remote
                    triggerAction: 'all',
                    emptyText: '请选择',
                     100,
                    displayField: 'param_value',
                    allowBlank: false,
                    blankText: "参数不允许为空",
                    listeners: {

                        select: function (combo) {

                            var quyu = form.getForm().findField("quyu").getValue();
                            form.getForm().findField("Name").clearValue(); //可以实现当队下拉值变更时，清空从动combo下拉选项中的值  

                            ProjectStore.load({ params: { quyu: quyu} });//加载第二个combo的数据源

                        }

                    }
                }]
            },
            {
                columnWidth: .25,
                layout: "form",
                items: [{
                    xtype: 'combo',
                    fieldLabel: "选择项目",
                    editable: false,
                    //是否允许输入 

                       hiddenName: 'Name',
                    store: ProjectStore,//数据源
                    mode: 'local',//第二个combo为local
                    triggerAction: 'all',
                    emptyText: '项目名称',
                     100,
                    displayField: 'name',
                    allowBlank: false,
                    blankText: "参数不允许为空"
                }]
            }