AngularJS下拉列表未显示选定值 [英] AngularJS dropdown not showing selected value
问题描述
在角度下拉列表中显示所选值时遇到问题。
当我给这样的时候它起作用
Am facing problem in displaying selected value in angular dropdown. it works when i give like this
$scope.selectedItem = $scope.items[1];
无效，如果我直接给出该值
not working, if i give directly that value
$scope.selectedItem = { name: 'two', age: 27 };
HTML ：
<html ng-app="app">
<body>
<div ng-controller="Test">
<select ng-model="selectedItem" ng-options="item.name for item in items">
</select>
</div>
</body>
</html>
JS ：
var app = angular.module('app',[]);
app.controller('Test',function($scope){
$scope.items = [{name: 'one', age: 30 },{ name: 'two', age: 27 },{ name: 'three', age: 50 }];
$scope.selectedItem = $scope.items[1];
});
CODEPEN：
http://codepen.io/anon/pen/zxXpmR
解决方案：
谢谢samir-das。我根据你的建议修好了。
Thank you samir-das. I fixed as per your suggestion.
var choosen_value = { name: 'two', age: 27 };
angular.forEach($scope.items, function(item){
if(angular.equals(choosen_value, item)){
$scope.selectedItem = item;
}
});
推荐答案
好吧，因为
$ scope.items [1] 和 {name：'two'，年龄：27} 是完全不同的事情。
$scope.items[1] and { name: 'two', age: 27 } is totally different thing.
{name：'two'，年龄：27} 是完全不同的对象，而 $ scope.items [1] 是对象的一部分 $ scope.items
{ name: 'two', age: 27 } is a totally different object whereas $scope.items[1] is part of the object $scope.items
当您使用 {{}} 在模板中放置某些内容时，angular会将其添加到其观察者列表中。
When you put something in the template using {{}}, angular add it in its watcher list.
因此当角度将它放入监视列表时，它就是一个对象（即 {name：'two'，年龄：27} ）与 $ scope.items 不同。
SO when angular put it in the watch list, it was an object (i.e. { name: 'two', age: 27 } ) that is different than $scope.items.
selectedItem 附加了您在控制器中设置的对象。总之，在脏检查时，angular将检查 selectedItem 对 {name：'two'，年龄：27} 不反对 $ scope.items
selectedItem is attached with the object that you set in the controller. In summary while dirty checking, angular will checks selectedItem against { name: 'two', age: 27 } NOT against $scope.items
希望你明白我的意思
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