Question

这是我上一期提问的代码：

getUserRole() {
  const headers = new Headers();
  headers.append('Authorization', `Bearer ${this.getToken()}`);
  console.log(this.getToken());
  const options = new RequestOptions({ headers: headers});

  return this.http.get(`${this.baseURL + this.loginApiRoot}/GetUserRoles`,options).pipe(map(res => res.json()))
    .subscribe(data => {
      this.userRole = JSON.stringify(data);
      if (this.userRole === 'parent') {
        this.logout();
      } else if (this.userRole === 'school') {
        this.isUser = true;
        this.isAdmin = false;
        this.cookieService.set('isSchool', '1');
      } else if (this.userRole === 'admin') {
        this.isUser = false;
        this.isAdmin = true;
        this.cookieService.set('isAdmin', '1');
      }
    });
}

但是当我在调用此函数后尝试访问userRole时，我得到userRole undefined，可能是因为它在.subscribe被点击之前被返回。

因此，我将其设为undefined：

var result = this.getUserRole(token);
console.log('Call from login ' + result);

所以，我已经改变了这样的方法：

getUserRole(roletoken: string) {
  const headers = new Headers();
  headers.append('Authorization', `Bearer ${roletoken}`);
  const options = new RequestOptions({ headers: headers});
  var result = this.http.get(`${this.baseURL + this.loginApiRoot}/GetUserRoles`, options).pipe(map(res => res.json()));
  console.log(result);
  return result;
}

但在这里，我result为[object object]。

我是否应该知道应该采用哪种方法立即通过任何一种方法分配userRole。

在第二种方法中，我无法将[object object]转换为值。

我从API收到的数据是这样的：

["school"]

这是呼叫：

this.getUserRole(token);
console.log('Call from login ' + this.userRole);

这是getUserRole函数内部：

var result = this.http.get(`${this.baseURL + this.loginApiRoot}/GetUserRoles`, options).subscribe(data => {
  this.userRole = JSON.stringify(data);
  console.log(data);
});

这是我得到的控制台序列：

从登录未定义呼叫

回复{_body：“[”school“]”，状态：200，ok：true，statusText：   “OK”，标题：标题，...}

因此，即使尝试使用订阅代码，userRole的分配也是通过登录调用来获得的。

Answer 1

getUserRole会返回Observable。正如您所见，您需要subscribe来进行HTTP调用并接收数据。由于您使用的是遗留Http类，而不是HttpClient，因此您需要将响应转换为实际的JSON数据。下面的代码应该有效：

getUserRole(roletoken: string) {
  const headers = new Headers();
  headers.append('Authorization', `Bearer ${roletoken}`);
  const options = new RequestOptions({ headers: headers});
  return this.http.get(`${this.baseURL + this.loginApiRoot}/GetUserRoles`, options).pipe(map(response => response.json()));
}

了解Observables和HTTP请求的异步性质非常重要。 this.userRole仅在请求完成后设置。因此，如果你想对this.userRole做一些事情并希望确定它有一个值，你应该在subscribe函数中使用它：

this.getUserRole(token).subscribe(userRole => { 
  this.userRole = userRole;
  console.log('Call from login ' + this.userRole);
});

Answer 2

我会做的是，如果你的休息api发给你一个json

    userRole: UserRole // here you set the type of userRole as UserRole that you defined earlier or in an other file
    getUserRole() {
  const headers = new Headers();
  headers.append('Authorization', `Bearer ${this.getToken()}`);
  console.log(this.getToken());
  const options = new RequestOptions({ headers: headers});
  return this.http.get<UserRole>(`${this.baseURL + this.loginApiRoot}/GetUserRoles`,options)
  .subscribe(data => {
  this.userRole = data;
    if (this.userRole === 'parent') {
      this.logout();
  } else if (this.userRole === 'school') {
    this.isUser = true;
    this.isAdmin = false;
    this.cookieService.set('isSchool', '1');
  } else if (this.userRole === 'admin') {
    this.isUser = false;
    this.isAdmin = true;
    this.cookieService.set('isAdmin', '1');
  }
  });

}

如果你的api发给我一个json的列表我会做的，（它可以是一个json的列表，如[{name：'name'，first_name：'first_name'}]）

    userRole: UserRole // here you set the type of userRole as UserRole that you defined earlier or in an other file
    getUserRole() {
  const headers = new Headers();
  headers.append('Authorization', `Bearer ${this.getToken()}`);
  console.log(this.getToken());
  const options = new RequestOptions({ headers: headers});
  return this.http.get<UserRole[]>(`${this.baseURL + this.loginApiRoot}/GetUserRoles`,options)
  .subscribe(data => {
  this.userRole = data[0];   // of course here if you want them all you will make a loop and use this.userRoles set as userRoles: UserRole[]
    if (this.userRole === 'parent') {
      this.logout();
  } else if (this.userRole === 'school') {
    this.isUser = true;
    this.isAdmin = false;
    this.cookieService.set('isSchool', '1');
  } else if (this.userRole === 'admin') {
    this.isUser = false;
    this.isAdmin = true;
    this.cookieService.set('isAdmin', '1');
  }
  });

}

看起来你的api不会给你一个json，如果它真的能给你类似的东西 ['学校'] 而不是[{role：'school'}]之类的东西我会试试

    getUserRole() {
  const headers = new Headers();
  headers.append('Authorization', `Bearer ${this.getToken()}`);
  console.log(this.getToken());
  const options = new RequestOptions({ headers: headers});
  return this.http.get(`${this.baseURL + this.loginApiRoot}/GetUserRoles`,options).pipe(map(res => res.json()))
  .subscribe(data => {
  this.userRole = JSON.stringify(data[0]);  // data is a list you take the first element 
    if (this.userRole === 'parent') {
      this.logout();
  } else if (this.userRole === 'school') {
    // same

}

或

    getUserRole() {
  const headers = new Headers();
  headers.append('Authorization', `Bearer ${this.getToken()}`);
  console.log(this.getToken());
  const options = new RequestOptions({ headers: headers});
  return this.http.get(`${this.baseURL + this.loginApiRoot}/GetUserRoles`,options).pipe(map(res => res.json()))
  .subscribe(data => {
  this.userRole = JSON.stringify(data);  // data is a list you take the first element 
    if (this.userRole[0] === 'parent') {
      this.logout();
  } else if (this.userRole[0] === 'school') {
    // same but you take the first element of the list

}

我不确定过去的2，因为我曾经从我的apis得到json的回应，但这是我第一次检查并看到我得到的

不要忘记你可以使用浏览器调试器在每一步调试并查看变量的值，就像你在chrome中一样，只需在函数开头设置断点并遵循它;）

从Angular4中的[object object]获取值

2 个答案: