Javascript 在 JSON 对象中转换承诺
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Convert promise in JSON object
提问by VitezKoja
I have a problem converting the promise returned by the service to the controller. What I want is to create an array of JSON objects from the data contained in promise. Here is what I receive in the controller:
我在将服务返回的承诺转换为控制器时遇到问题。我想要的是从 promise 中包含的数据创建一个 JSON 对象数组。这是我在控制器中收到的内容：
Here is the line that is used for printing that data:
这是用于打印该数据的行：
console.log("controller unmatched: ", unmatched.getData(sFilter));
Here "unmatched" is the service, and getData() is its function.
这里“unmatched”是服务，getData() 是它的函数。
Thanks!
谢谢！
回答by Lennholm
A Promise represents a value that will be available some time in the future, or never. This means its eventual value can't be returned by your unmatched.getData()function.
Promise 代表一个值，该值将在未来某个时间可用，或者永远不会可用。这意味着您的unmatched.getData()函数无法返回其最终值。
What you need to do is to make unmatched.getData()return the actual promise and then you take action when that promise resolves:
您需要做的是unmatched.getData()返回实际的承诺，然后在该承诺解决时采取行动：
unmatched.getData(sFilter).then(function(result) {
console.log("controller unmatched: ", result);
});
回答by Vladimir Zdenek
I believe what you really want to do is save a value the promise resolves to, not the promise itself.
我相信你真正想做的是保存承诺解决的价值，而不是承诺本身。
unmatched.getData(sFilter).then(response => {
const json = JSON.stringify(response);
});
This is due to the nature of promises - they are asynchronous.
这是由于 Promise 的性质——它们是异步的。
The Promise object represents the eventual completion (or failure) of an asynchronous operation, and its resulting value.
Promise 对象表示异步操作的最终完成（或失败）及其结果值。
Source: Promises on MDN
资料来源：MDN 上的承诺
回答by Hitmands
Promises work async:
Promise 异步工作：
unmatched
.getData(sFilter)
// wait for its resolution
.then(data => console.log(JSON.stringify(data))
;
回答by Harikrishnan S
if you want to get the JSON objects from the promise, I think you can use the below line of code
如果您想从承诺中获取 JSON 对象，我认为您可以使用以下代码行
response.json()
响应.json()
