如何获得已经解决的承诺的价值? [英] How to get value of promise that already resolved?

问题描述

我有一个承诺，我将绑定到我的 UI 中.当承诺解决并且 UI 元素呈现时，我可以单击该 UI 元素.在我处理点击的控制器代码中，我想对承诺的价值采取行动.在我的角度代码的这一点上，我已经知道承诺已解决..但是当我想获得价值时，它仍然是一个承诺.

I have a promise that I am binding to in my UI. When the promise resolves and the UI element renders I can then click on that UI element. In my controller code where I handle the click I would like to act on the value of the promise. At this point in my angular code I already know that the promise is resolved.. but when I want to get the value its still a promise.

获得承诺价值的最佳方法是什么...鉴于我知道它一定已经解决了?

Whats the best way to get the value of the promise... given that I know it must have resolved?

推荐答案

承诺永远是承诺 - 这就是它们应该的样子.虽然可以将 promise 直接绑定到视图，但我通常不鼓励这种做法，因为它缺乏透明度并可能导致视图闪烁.更好的解决方案是在 then 调用中分配范围值:

Promises are always promises - and that's how they should be. While it is possible to bind a promise directly to the view, I generally discourage this practice because it lacks transparency and can lead to view flickering. A better solution is to assign a scope value in a then call:

myService.then(function( val ) {
  $scope.val = val;
});

当 $scope.val 准备好时，它总是可以被直接视为一个值 - 因为它是.

When $scope.val is ready, it can always be treated directly as a value - because it is.

也就是说，如果你想直接做promise赋值，你只需要把它当作一个promise；也就是说，你需要调用promise.then(function () { ... });.这看起来很不方便，但实际上证明了 Promise 的强大.

That said, if you want to do the promise assignment directly, you just have to treat it like a promise; that is, you need to call promise.then(function () { ... });. This seems like an inconvenience, but it's actually a testament to just how powerful promises are.

如果你想了解更多关于 promise 的信息，我在最近的一次 Google+ Hangout 中对它们进行了描述(并提供了代码示例)，其中我介绍了 AngularJS 中 promise 的优点、常见用途和最佳实践:AngularJS Hangout -- 承诺，承诺承诺，承诺.永无止境的承诺链的想法得到了特别的解决，尽管我的脑海中没有时间码.

If you want some more info on promises, I pontificated on them (and provided code examples) for a recent Google+ Hangout, where I covered the advantages, common uses, and best practices of promises in AngularJS: AngularJS Hangout -- Promises, Promises Promises, Promises. The idea of never-ending promise chains was specifically addressed, though I don't have a timecode off the top of my head.

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