Question

假设我有自定义方向控制数字的数量。

myApp.directive('myMaxlength', ['$compile', '$log', function($compile, $log) {
    return {
        restrict: 'A',
        require: 'ngModel',
        link: function (scope, elem, attrs, ctrl) {
            attrs.$set("ngTrim", "false");
            var maxlength = parseInt(attrs.myMaxlength, 10);
            ctrl.$parsers.push(function (value) {
                $log.info("In parser function value = [" + value + "].");
                if (value.length > maxlength)
                {
                    $log.info("The value [" + value + "] is too long!");
                    value = value.substr(0, maxlength);
                    ctrl.$setViewValue(value);
                    ctrl.$render();
                    $log.info("The value is now truncated as [" + value + "].");
                }
                return value;
            });
        }
    };
}]);

例如，当我写my-maxlength="10"时，用户不能写更多问题是当我将此指令添加到angularUi Datepicker时，我收到错误：

Error: value is null .link/<@http://andcweb.com/App/Directives/maxlength.js:10:1 NgModelController

HTML

                    <input type="text" name="birth" class="form-control"
                           datepicker-popup-persian="{{format}}"
                           tabindex="7"
                           ng-model="requesterViewModel.BirthDate"
                           is-open="datePicker.opened"
                           datepicker-options="dateOptions"
                           date-disabled="disabled(date, mode)"
                           close-text="بسته"
                           min-date="minDate" max-date="dt" my-maxlength="6" />
                    <span class="input-group-btn">
                        <button type="button" class="btn btn-default iconBtn" ng-click="openPersian($event)"><i class="fa fa-calendar"></i></button>
                    </span>

有什么想法吗？非常感谢

Answer 1

请仔细阅读错误消息：

Error: value is null .link/<@http://andcweb.com/App/Directives/maxlength.js:10:1 NgModelController

此消息提供发生错误的确切行号以及错误的明确说明。

if (value.length > maxlength) { ... }

应该是：

if (value && value.length > maxlength) { ... }

否则，当$ viewValue为length时，您可能会尝试阅读null的{{1}}属性。

datePicker上的自定义指令不起作用

1 个答案: