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

问题描述

我想知道如果我在与 in 相同的元素上有一个控制器和 ng-if 指令

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>

还有一个控制器，比如

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

我是否应该看到你可以看到我"的文字?

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

推荐答案

这就是答案.我不会看到文字.基本上，ng-if 是一个嵌入指令，这意味着整个元素都被从 DOM 中剥离出来，并且在 ng-if 实例化 Block 之前不会实例化其他指令，但这永远不会发生，因为 ctrl.visible 甚至从未在示波器上发布过，所以它总是假的……鸡和蛋的问题.实际上，情况可能更糟:ctrl 可能是父控制器，如果该控制器碰巧具有可见字段，则可能会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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