Does anyone know why in Angular, the select selector doesn't work without the ng-model?

<select ng-model="bla_bla" ng-options="obj.value as obj.key for obj in languages"/>
<select ng-options="obj.value as obj.key for obj in languages"/>

code的第一行，将工作，而第二个将无法工作。为什么???

The first line of code above will work while the second one will not work. Why ???

谢谢！

推荐答案

使用角应用内的选标记生成 NG-选择指令，这是一个HTML SELECT 元素加上棱角分明的数据绑定。展望本选择指令的角源，这里有从链接方法的前几行：

Using the select tag within an Angular app generates the ng-select directive, which is an HTML SELECT element plus angular data-binding. Looking in the Angular source for this select directive, here are the first few lines from its link method:

link: function(scope, element, attr, ctrls) {
    // if ngModel is not defined, we don't need to do anything
    if (!ctrls[1]) return;
    ...

所以，它实际上是建立在框架中止贯通指令如果 ngModel 没有定义，因此没有约束力的发生。

So it is actually built into the framework to abort linking the directive if ngModel is not defined, and so no binding takes place.