javascript - Angular : how to bind to required/ngRequired

Question

我有这个指令，它可以是必需的，也可以不是。它可以有两种使用方式(据我所知)

<my-foo required></my-foo>

或

<my-foo ng-required="data.value > 10"></my-foo>

所以，因为 require and ngRequire are basically the same thing你会认为指令可以做到这一点

HTML:

<my-foo ng-require="data.isRequired"></my-foo>

JS:

...
.directive('myFoo', function () {
    return {
    restrict: 'E',
    scope: {
       required: '='
    }
    ...

DEMO

嗯，不，这行不通，scope.require 是 undefined。您实际上必须将范围定义更改为

scope: {
    required: '=ngRequired'
}

所以问题是处理这两种情况的首选方法是什么，以便将值存储在 scope.required 中？我应该同时定义两者还是使用链接函数中的属性？

Answer 1

您基本上可以选择两种方法:

1。支持 ng-model

的自定义表单元素

如果您查看ng-required 指令源代码，您会发现它只处理ng-model controller。 :

restrict: 'A',
require: '?ngModel',
link: function(scope, elm, attr, ctrl) {
  if (!ctrl) return;
  attr.required = true; // force truthy in case we are on non input element

  ctrl.$validators.required = function(modelValue, viewValue) {
    return !attr.required || !ctrl.$isEmpty(viewValue);
  };

  attr.$observe('required', function() {
    ctrl.$validate();
  });
}

因此，如果您的自定义指令支持 ng-model，那么您已经支持 ng-required 即:

angular.module('test', [])
.directive('myInput', function(){
  return {
    restrict: 'E',
    require: 'ngModel',
    scope: true,
    template: '<div><button ng-click="changeValue()">Change Value from: {{currentValue}}</button></div>',
    link: function (scope, element, attrs, ngModelCtrl) {
        ngModelCtrl.$parsers.push(function(val){
          if(!val){
            return null;
          }
          return parseFloat(val, 10) * 100;
        });
        ngModelCtrl.$render = function() {
           scope.currentValue = ngModelCtrl.$viewValue || 'No value';
        };
        scope.changeValue = function read(){
          var newValue = Math.random();
          if(newValue > 0.5){
            ngModelCtrl.$setViewValue(newValue + "");
          } else {
            ngModelCtrl.$setViewValue(null);
          }
          ngModelCtrl.$render();
        };
    }
  };
});

2。包装现有指令并传递 ng-required:

angular.module('test', [])
  .directive('myFormElement', function() {
      return {
        restrict: 'E',
        scope: {
          model: '=',
          required: '='
        },
        template: '<div>Enter number: <input type="number" ng-model="data.number" ng-required="required"></div>'
  };

  });

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>


<div ng-app="test" ng-init="data={value:'Initial', required: false}">
  <form>
    Is required: <input type="checkbox" ng-model="data.required">
    <my-form-element required="data.required" model="data"></my-form-element>
  </form>
</div>