ExtJs 4 ComboBox 异步加载 格式 示例

                        name: "U_Type",
                        fieldLabel: "用户类型",
                        xtype: "combo",
                        //传入后台真实值value field /value
                        editable: false,
                        anchor: '90%',
                        store: Ext.create('Ext.data.Store', {
                            autoLoad: true, // 必须自动加载, 否则无在编辑的时候load
                            proxy: {
                                actionMethods: 'post',
                                type: 'ajax',
                                url: "/Sys_Roles/List/l"
                            },
                            fields: ['R_RoleName','RoleID'],
                            listeners: {
                                beforeload: function (s, e) {
                                    e.params = { limit:100,start:0 }; //ajax 附加参数
                                }
                            }
                        }),
                        queryMode: 'local',
                        displayField: 'R_RoleName',
                        typeAhead: true,
                        valueField: 'RoleID' 

 json格式为：

[{"DataTable_Action":0,"RoleID":2,"R_UserID":1,"R_RoleName":"管理用户","R_Description":"管理用户"},{"DataTable_Action":0,"RoleID":1,"R_UserID":1,"R_RoleName":"普通用户","R_Description":"普通用户"}]