点击按钮弹出表单之前，调后台方法判断是否能够弹出

<a href="javascript:void(0)"
       data-toggle="topjui-menubutton"
       data-options="method: 'openDialog',
            extend: '#productDg-toolbar',
            iconCls: 'fa fa-pencil',
            btnCls: 'topjui-btn-green',
            grid: {
                type: 'datagrid',
                id: 'productDg'
            },
            dialog: {
                title:'普通布局的表单',
                href: _ctx + '/html/complex/dialog_edit.html?uuid={uuid}',
                url: _ctx + '/json/product/detail.json?uuid={uuid}',
                buttonsGroup: [
                    {
                        text: '自定义方法',
                        url: _ctx + '/json/response/success.json',
                        iconCls: 'fa fa-cog',
                        handler: 'myQuery',
                        btnCls: 'topjui-btn-brown'
                    },
                    {
                        text: '更新',
                        url: _ctx + '/json/response/success.json',
                        iconCls: 'fa fa-save',
                        handler: 'ajaxForm',
                        btnCls: 'topjui-btn-green'
                    }
                ]
            }">编辑</a>