javascript - Angularjs: ngDialog 只绑定(bind)和修改对象；不是基本变量。

Question

我已经找到了这个问题的“解决方案”；我只是希望有人能够提供它起作用的原因。

这个 jsFiddle 演示了这个问题: http://jsfiddle.net/s1ca0h9x/137/

HTML

<div data-ng-app="myApplication">
    <div data-ng-controller="MainController">
<a href="" ng-click="ShowNgDialog()">Click Here</a>

        <input type="text" ng-model="accountNum" />
        <span>{{accountNum}}</span>

    </div>
</div>

Angular

var myApplication = angular.module('myApplication', ['ngDialog']);

myApplication.controller('MainController', function ($scope, ngDialog) {
    $scope.accountNum = 'test';
    $scope.ShowNgDialog = function () {
        ngDialog.open({            
            template: '<div><input type="text" ng-model="accountNum"/></div>',
            plain: true,
            scope:$scope

        });
    }    
});

当我尝试从对话框中操作范围变量(在本例中:$scope.accountNum = 'test')时，它不会将其绑定(bind)/保存回模型。

...但是，当我将该变量更改为一个对象时，事情就神奇地起作用了，如本演示所示:http://jsfiddle.net/s1ca0h9x/138/

HTML

<div data-ng-app="myApplication">
    <div data-ng-controller="MainController">
<a href="" ng-click="ShowNgDialog()">Click Here</a>

        <input type="text" ng-model="FormData.accountNum" />
        <span>{{FormData.accountNum}}</span>

    </div>
</div>

Angular

var myApplication = angular.module('myApplication', ['ngDialog']);

myApplication.controller('MainController', function ($scope, ngDialog) {
    $scope.FormData={accountNum: ''};
    $scope.ShowNgDialog = function () {
        ngDialog.open({            
            template: '<div><input type="text" ng-model="FormData.accountNum"/></div>',
            plain: true,
            scope:$scope

        });
    }    
});

除了尝试 ngDialog.openConfirm 等之外，我还使用链接到文件的模板而不使用 plain:true 测试了这两个选项。我基本上重建了此处找到的解决方案 ngDialog $scope variables not being updated by ngModel fields in $dialog when using scope: $scope一点一点，最后似乎唯一有效的更改是使用对象而不是基本范围变量。我是不是处理错了，或者遗漏了数据绑定(bind)的一些基本方面？

Answer 1

我认为这与绑定(bind)无关。当我深入研究 ngDialog 的代码时，我将解释我所理解的内容。和 AngularJS .

我认为第一种情况没有像您预期的那样工作，因为 $scope.accountNum = 'test'; 是一个简单的字符串，它是原始类型并且不可变( ref ) 或者换句话说是不可变的:

Mutable is a type of variable that can be changed. In JavaScript, only objects and arrays are mutable, not primitive values. (You can make a variable name point to a new value, but the previous value is still held in memory. Hence the need for garbage collection.)

A mutable object is an object whose state can be modified after it is created.

Immutables are the objects whose state cannot be changed once the object is created.

String and Numbers are Immutable.

所以，简而言之，这就是第一个变体无法按您的意愿工作的原因:)

---

现在让我们看看this ngDialog 的代码，它是 open() 的一部分方法:

var scope;
scopes[dialogID] = scope = angular.isObject(options.scope) ? options.scope.$new() : $rootScope.$new();

在您的例子中，我们正在调用 options.scope.$new()，因为您在打开对话框时在选项中指定了 scope。

现在我们去检查this Angular 代码:

$new: function (isolate, parent) {
    var child;  
    parent = parent || this;

    if (isolate) {
        child = new Scope();
        child.$root = this.$root;
    } else {
        if (!this.$$ChildScope) {
            this.$$ChildScope = createChildScopeClass(this); // <---- WE ARE COMING HERE NOW
        }
        child = new this.$$ChildScope();
    }
    ...

函数createChildScopeClass看起来像:

function createChildScopeClass(parent) {
    function ChildScope() {
        this.$$watchers = this.$$nextSibling =
                this.$$childHead = this.$$childTail = null;
        this.$$listeners = {};
        this.$$listenerCount = {};
        this.$$watchersCount = 0;
        this.$id = nextUid();
        this.$$ChildScope = null;
    }
    ChildScope.prototype = parent; /* <--- They simply assign the derived scope 
     as prototype of the new one (which is going to be the scope of the ngDialog) */
    return ChildScope;
}

我们可以看到 函数 createChildScopeClass() 只是将父作用域的原型(prototype)分配给新的原型(prototype)(这将成为打开的 ngDialog 的作用域)

还有一个演示可变性和不变性的示例:

var test = 'test'; 
var test2 = test;
test2 = 'new value';
console.log('test = ' + test + ' // test2 = ' + test2);

var testObj = {test: 'test'};
var test2Obj = testObj;
test2Obj.test = 'new value';
console.log('testObj.test = ' + testObj.test + ' // test2Obj.test = ' + test2Obj.test);

结论

如果您希望绑定(bind)在派生范围内工作，请在父范围内使用对象 或数组。使用 AngularJS 的示例:

var app = angular.module('sample', []);

app.controller('AppController', ['$scope', function($scope) {

  $scope.primitive = 'test';
  $scope.obj = {
    test: 'test initial'
  };

  $scope.newScope = $scope.$new();
  $scope.newScope.primitive = 'test 2';
  $scope.newScope.obj.test = 'updated value';

}]);

app.run();

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="sample">
  <div ng-controller="AppController">
    <table>
      <thead><tr><th>Property</th><th>Value</th><th></th></tr></thead>
      <tbody>
        <tr>
          <td>primitive</td>
          <td>{{ primitive }}</td>
          <td><input type="text" ng-model="primitive"></td>
        </tr>
        <tr>
          <td>obj.test</td>
          <td>{{ obj.test }}</td>
          <td><input type="text" ng-model="obj.test"></td>
        </tr>
        <tr>
          <td>newScope.primitive</td>
          <td>{{ newScope.primitive }}</td>
          <td><input type="text" ng-model="newScope.primitive"></td>
        </tr>
        <tr>
          <td>newScope.obj.test</td>
          <td>{{ newScope.obj.test }}</td>
          <td><input type="text" ng-model="newScope.obj.test"></td>
        </tr>
      </tbody>
    </table>
  </div>
</div>