离子 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.

第一:

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:

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，可能会出现什么问题?

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

推荐答案

响应状态为:0 对于 URL:null

Response with status:0 for URL: null

这似乎与 CORS 问题有关...请检查您的后端代码中是否启用了 CORS.

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?

http.get() 返回一个 Observable，所以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); });

如果你需要返回一个承诺，那么你可以这样做:

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();
}

并像这样使用它

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

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