如何设置一个默认值NG-选项（多选） [英] How to set a default value to ng-options (multiple select)
问题描述
我想通过设置一个默认值，我的NG选项 NG-INIT ， NG-模型等他们并没有在所有的工作。我的code为以下内容：
I wanted to set a default value to my ng-options by using ng-init, ng-model, etc. They didn't work at all. My code is following:
角
var app = angular.module('role', []);
app.controller('fooController', function($scope){
$scope.roles = [{id:1, name:"Administrator"}, {id:2, name: "Student"}];
$scope.user.roles = $scope.roles[0];
});
HTML
<body data-ng-app="role" data-ng-controller="fooController">
<select multiple class="form-control" data-ng-model="user.roles" data-ng-options="role.name for role in roles" required=""></select>
</body>
下面是我的 Plunkr。
任何帮助将是AP preciated。
Here is my Plunkr. Any help would be appreciated.
推荐答案
下面是我工作：
app.controller('fooController', function($scope){
$scope.roles = [{id:1, name:"Administrator"}, {id:2, name: "Student"}];
$scope.user = {};
$scope.user.roles = [ $scope.roles[0] ];
});
有没有在这普拉克用户未初始化错误，除了这个，角将在中的每个对象比较NG选项数组中的每个元素在 NG-模型阵列。 JavaScript的比较没有棱角比较，比较，即使相同属性的两个对象在JavaScript中返回false（不同的对象）。
There was an error in the plunk that user wasn't initialized, apart from this, Angular would compare every object in the ng-options array to every element in the ng-model array. JavaScript comparison not Angular comparison, comparing 2 objects even with same properties in JavaScript returns false (different objects).
普拉克：<一href=\"http://plnkr.co/edit/ccsAVvPACnN6Qzje7HcB?p=$p$pview\">http://plnkr.co/edit/ccsAVvPACnN6Qzje7HcB?p=$p$pview
现在，这是不理想的。通常情况下，你要根据ID或因此这些相关的，这里的另一种方式：
Now, this is not ideal. Typically you want to correlated these based on ID or so, here's another way:
在HTML中，使用通过跟踪，告诉AngularJS比较的ID，而不是整个对象：
In HTML, use track by, to tell AngularJS to compare IDs instead of entire objects:
<select multiple class="form-control"
data-ng-model="user.roles"
data-ng-options="role.name for role in roles track by role.id"
required=""></select>
然后在你的控制器，你可以使用任何对象，而无需在阵列中居然是：
Then in your controller, you can use any object without actually being in the array:
app.controller('fooController', function($scope){
$scope.roles = [{id:1, name:"Administrator"}, {id:2, name: "Student"}];
$scope.user = {};
$scope.user.roles = [ {id:1, name:"Administrator"} ];
});
普拉克：<一href=\"http://plnkr.co/edit/NKLXrwqwk36YfhBSXILN?p=$p$pview\">http://plnkr.co/edit/NKLXrwqwk36YfhBSXILN?p=$p$pview
请注意，我甚至没有需要名称属性。这只是供以后作出适当的对象，但它确实是没有必要现在匹配，尝试没有它！
Note that I didn't even need the name property. It's just for making a proper object later, but it really isn't needed for matching now, try without it!
我写了一个很长的教程和视频在这个最初的选择问题。它不包括多选，但是这只是使用一个数组，而不是直接的对象。检查出来的更多的理解：
I wrote a long tutorial and video on this initial selection problem. It doesn't cover multiselect but that's just using an array instead of the object directly. Check it out for more understanding:
<一个href=\"http://gurustop.net/blog/2014/01/28/common-problems-and-solutions-when-using-select-elements-with-angular-js-ng-options-initial-selection/\">Solving最初的选择问题在Angular.JS选择，与轨道NG选项由
让我知道意见，如果你还在为此苦苦挣扎。
Let me know in comments if you are still struggling with this.
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