我可以把ng-if指令放在一个也绑定到控制器的元素上 [英] Can I put ng-if directive on an element which also binds to a controller

问题描述

我想知道如果我有一个控制器和ng-if指令与

I was wondering in case I have a controller and ng-if directive on the same element as in

<div foo ng-if="ctrl.visible">You can see me</div>

和控制器，例如

NgController(selector: ‘[foo]’,….)
class FooController { var visible = true; }

我应该看到文字你可以看到我吗？

Should I see the text "You can see me" or not?

推荐答案

这里是答案，我不会看到的文本基本上， ng-if transcluding指令，这意味着整个元素被从DOM中删除，没有其他指令被实例化，直到ng - 如果实例化块，但不会发生，因为 ctrl.visible 是从来没有在范围上发布，所以它总是falsy ...鸡和蛋的问题。其实，甚至可能更糟： ctrl 可以是父控制器，如果控制器有可见字段，它可能导致不可预测的行为。

Here's the answer. I would not see the text. Basically, ng-if is a transcluding directive which means that the entire element is ripped out of the DOM and no other directives are instantiated until ng-if instantiates the Block, but that never happens because ctrl.visible is never even published on the scope, so it's always falsy... chicken and egg problem. Actually, it can be even worse: ctrl could be the parent controller, and if that controller happen to have visible field it can cause unpredictable behavior.

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