Ionic 2 http.get（）问题 [英] Ionic 2 http.get() issue

问题描述

我尝试使用这两种方法进行 http.get（）调用。

I tried to make a http.get() call with these two methods.

首先：

getResults(){
    return this.http.get('http://localhost/api.php')
    .toPromise()
    .then( data => data.json() );
}

错误显示：

3     122412   error    EXCEPTION: Uncaught (in promise): Response with status:0  for URL: null
4     122413   error    ORIGINAL STACKTRACE:
5     122413   error    Error: Uncaught (in promise): Response with status: 0  for URL: null
..........

第二名：

getResults(){
    return new Promise((resolve, reject) => {
      this.http.get('http://localhost/api.php')
        .map(res => res.json())
        .subscribe(data => {
          resolve(data);
        }, (err) => {
          reject(err);
        });
    });
}

错误显示：

2     925052   error    EXCEPTION: Uncaught (in promise): Response with status:0  for URL: null
3     925052   error    ORIGINAL STACKTRACE:
4     925053   error    Error: Uncaught (in promise): Response with status: 0  for URL: null
.......

我应该使用哪种方法以及可能出现的问题？

Which method should I use and what could be the issue?

推荐答案

回复状态：0表示URL：null

Response with status:0 for URL: null

这似乎与CORS问题有关...请检查CORS是否已启用你的后端代码。

That seems to be related to a CORS issue... please check that CORS is enabled in your backend code.

我应该使用哪种方式？

Which way should i use?

http.get（）返回一个Observable，因此使用它的一种方法是

http.get() returns an Observable, so one way to use it would be

getResults(){
  this.http.get('http://localhost/api.php')
           .map(res => res.json());
}

然后当你调用那个方法时，你需要这样做：

And then when you call that method, you need to do it like this:

this.yourService.getResults().subscribe((data) => { console.log(data); });

如果您需要退回承诺，那么您可以这样做：

If you need to return a promise, then you can do it like this:

getResults(){
  this.http.get('http://localhost/api.php')
           .map(res => res.json())
           .toPromise();
}

并像这样使用

this.yourService.getResults().then((data) => { console.log(data); });

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