angularjs – 焦点打开列表

lima3app.directive('typeaheadOpenOnFocus',function() {
    return {
        require: ['ngModel'],link: function(scope,element,attr,ctrls) {
            element.bind('focus',function() {
                ctrls.$setViewValue('');
                console.log('customer.customer');
            });
        }
    };

});

所以在视图中我设置了我的输入：

<input type="text" class="form-content req" id="form-customer"
       name="formcustomer"
       typeahead="customer as customer.customer for customer in customerList | filter:{customer:$viewValue}"
       typeahead-on-select="onCustomerSelect($item)"
       typeahead-append-to-body="true"
       typeahead-open-on-focus

       ng-model="customer.customer"
       focus="true"
       required="required">

但代码,不起作用.有没有办法做到这一点？