Question

我得到异常'无法读取属性'订阅'未定义'但我不知道我做错了什么。

checkUserCredentials() {
    let response;
    let user = {email: this.email, password: this.password};
    this.userService.getUser(user).subscribe((res) => response = res);
  }

服务：

getUser(user): any {
    //this.http.get('http://localhost:3000/users?email = '+user.email+'&password='+user.password,
    let headers = new Headers();
    let postResponse;
    headers.append('Content-Type', 'application/json');
    this.http.post('http://localhost:3000/users',
        JSON.stringify(user),
        {headers:headers})
        .map((res: Response) => res.json())
  }

Answer 1

您需要在getUser方法中返回：

getUser(user): any {
  let headers = new Headers();
  let postResponse;
  headers.append('Content-Type', 'application/json');
  return this.http.post('http://localhost:3000/users',
    JSON.stringify(user),
    {headers:headers})
    .map((res: Response) => res.json())
}

Answer 2

缺少return。该方法不返回任何内容，因此隐式返回undefined，这会导致错误：

getUser(user): any {
    //this.http.get('http://localhost:3000/users?email = '+user.email+'&password='+user.password,
    let headers = new Headers();
    let postResponse;
    headers.append('Content-Type', 'application/json');
    // vvv missing return
    return this.http.post('http://localhost:3000/users',
        JSON.stringify(user),
        {headers:headers})
        .map((res: Response) => res.json())
  }

Angular 2订阅不起作用

2 个答案: