如何使用 angular.fromJson() 从 ng-repeat 获取对象答案

【问题标题】：How to get object from ng-repeat using angular.fromJson()如何使用 angular.fromJson() 从 ng-repeat 获取对象
【发布时间】：2017-06-22 12:10:42
【问题描述】：

如果我使用 ng-option 我可以从选择值中获得一个对象，但是，如果我在选项指令上使用 ng-repeat，我只能得到字符串。我正在尝试使用 angular.fromJson() 将字符串从 ng-repeat 转换为对象，但我失败了：我的代码是：

<!DOCTYPE html>
<html>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.4/angular.min.js"></script>
<body>

<div ng-app="myApp" ng-controller="myCtrl">

<p>Select a car:</p>

<select ng-model="selectedCar">
<option ng-repeat="(x, y) in cars" value="{{y}}">{{y.brand}}</option>
</select>

<input type="text" value="{{selectedCar}}">
<h1>You selected: {{selectedCarObj.brand}}</h1>
<h2>Model: {{selectedCarObj.model}}</h2>
<h3>Color: {{selectedCarObj.color}}</h3>

<h1>You selected: {{selectedCar}}</h1>
<h2>Model: {{selectedCar}}</h2>
<h3>Color: {{selectedCar}}</h3>

<p>The visible text inside the dropdown list can also be a property of the value object.</p>

</div>

<script>
var app = angular.module('myApp', []);
app.controller('myCtrl', function($scope) {
    $scope.cars = {
        car01 : {brand : "Ford", model : "Mustang", color : "red"},
        car02 : {brand : "Fiat", model : "500", color : "white"},
        car03 : {brand : "Volvo", model : "XC90", color : "black"}
    }
    $scope.selectedCarObj = angular.fromJson($scope.selectedCar);
});
</script>

</body>
</html>

如果我换行：

$scope.selectedCarObj = angular.fromJson($scope.selectedCar);

收件人：

$scope.selectedCarObj = angular.fromJson({brand : "Ford", model : "Mustang", color : "red"});

它正在工作！

为什么我无法获得 {{selectedCarObj.brand }} 值？

在选择列表中，选项值为：

<option ng-repeat="(x, y) in cars" value="{"brand":";Fiat";,";model":"500","color":"white"}" class="ng-binding ng-scope">Fiat</option><!-- end ngRepeat: (x, y) in cars -->

有人可以帮我理解为什么它不起作用吗？

也许是 html 字符？！？

非常感谢。

【问题讨论】：

标签： angularjs json angularjs-ng-repeat ng-options angularjs-ng-options

【解决方案1】：

您缺少 ng-change ：

var app = angular.module('myApp', []);
app.controller('myCtrl', function($scope) {
    $scope.cars = {
        car01 : {brand : "Ford", model : "Mustang", color : "red"},
        car02 : {brand : "Fiat", model : "500", color : "white"},
        car03 : {brand : "Volvo", model : "XC90", color : "black"}
    }
    $scope.GetObject = function(){
    $scope.selectedCarObj = angular.fromJson($scope.selectedCar);
    
}
});

<html>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.4/angular.min.js"></script>
<body>

<div ng-app="myApp" ng-controller="myCtrl">

<p>Select a car:</p>

<select ng-model="selectedCar" ng-change="GetObject()">
<option ng-repeat="(x, y) in cars" value="{{y}}">{{y.brand}}</option>
</select>

<input type="text" value="{{selectedCar}}">
<h3>Json: {{selectedCar}}</h3>
object is :
<h3>brand: {{selectedCarObj.brand}}</h3>
<h3>model: {{selectedCarObj.model}}</h3>
<h3>color: {{selectedCarObj.color}}</h3>

<p>The visible text inside the dropdown list can also be a property of the value object.</p>

</div>
</body>
</html>

【讨论】：

太棒了！非常感谢你！我错过了 ngChange 指令。再次感谢 ;-)

【解决方案2】：

另一种替代解决方案是创建自定义过滤器，将字符串转换为对象并返回相关属性

app.filter('jsonFilt',function(){
  return function(item,name){
     if(item){
       item = JSON.parse(item);
       return item[name];
     } 
  }
});

像这样在html中调用过滤器

<input type="text" value="{{selectedCar}}">
<h1>You selected: {{selectedCar | jsonFilt : 'brand'}}</h1>
<h2>Model: {{selectedCar | jsonFilt : 'model'}}</h2>
<h3>Color: {{selectedCar | jsonFilt : 'color'}}</h3>

演示

var app = angular.module('myApp', []);
app.controller('myCtrl', function($scope) {
    $scope.cars = {
        car01 : {brand : "Ford", model : "Mustang", color : "red"},
        car02 : {brand : "Fiat", model : "500", color : "white"},
        car03 : {brand : "Volvo", model : "XC90", color : "black"}
    }
    $scope.selectedCarObj = angular.fromJson($scope.selectedCar);
});
app.filter('jsonFilt',function(){
  return function(item,name){
     if(item){
       item = JSON.parse(item);
       return item[name];
     } 
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="myApp" ng-controller="myCtrl">

<p>Select a car:</p>

<select ng-model="selectedCar">
<option ng-repeat="(x, y) in cars" value="{{y}}">{{y.brand}}</option>
</select>

<input type="text" value="{{selectedCar}}">
<h1>You selected: {{selectedCar | jsonFilt : 'brand'}}</h1>
<h2>Model: {{selectedCar | jsonFilt : 'model'}}</h2>
<h3>Color: {{selectedCar | jsonFilt : 'color'}}</h3>

<h1>You selected: {{selectedCar}}</h1>
<h2>Model: {{selectedCar}}</h2>
<h3>Color: {{selectedCar}}</h3>

<p>The visible text inside the dropdown list can also be a property of the value object.</p>

</div>

【讨论】：

非常感谢。带过滤器也是一种选择。我只是想了解 ngOption 和 ngRepeat 之间的区别。再次感谢。