在角6中向http.get添加标头

Question

我试图从deerawan修改工作示例，以包含另一个需要标题的网站的标题。我得到了下面的解决方案，它似乎工作得很好。但是当我添加subscribe()时，它仍然工作，但在控制台中得到异常：

我该怎么做才能修复这个警告信息？谢谢。

原始代码：

export class UserService {

  private serviceUrl = 'https://jsonplaceholder.typicode.com/users';

  constructor(private http: HttpClient) { }

  getUser(): Observable<User[]> {
    return this.http.get<User[]>(this.serviceUrl);
  }
}

解决方案代码：

export class NWSForecast {
  private config = {
    headers: {
      'User-Agent' : 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.153 Safari/537.36'
    }
  };

  private serviceUrl = 'https://api.weather.gov/gridpoints/OKX/36,38/forecast';

  constructor(private http: HttpClient) { }

  getUser(): Observable<any>  {
    // first argument is URL, put config as second argument
    return this.http.get<any>(this.serviceUrl, this.config);
  }
}

修改了解决方案，以捕获响应。但它也有例外：

export class AppComponent {
  private config = {
    headers: {
      'User-Agent' : 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.153 Safari/537.36'
    }
  };
  weathers: any;
  private serviceUrl = 'https://api.weather.gov/gridpoints/OKX/36,38/forecast';

  constructor(private http: HttpClient) { }

  getWeather() {
    this.http.get<Weather>(this.serviceUrl, this.config).subscribe(
      val => {
        this.weathers = val;
      console.log('this.weather ====> ', this.weathers);
      });
    }
}

控制台中的错误消息：Refused to set unsafe header "User-Agent" http.js:1436

Answer 1

因为需要将URL作为get的第一个参数来提供，所以您得到了错误。

 this.http.get<Weather>(url, this.config);

Answer 2

角的http.get()采用两个参数，网址和选项。您将它们作为1传递，这就导致了这个问题！下面是我经常在第7角中向服务添加自定义头的方式：

import { HttpClient, HttpHeaders } from '@angular/common/http';

export class NWSForecast {
  private headerObj = new HttpHeaders({'User-Agent' : 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.153 Safari/537.36'})

  private serviceUrl = 'https://api.weather.gov/gridpoints/OKX/36,38/forecast'

  constructor(private http: HttpClient) { }

  getUser(): Observable<Weather>  {
    console.log(this.http.get<Weather>(this.config));
    return this.http.get<Weather>(this.serviceUrl, {headers: this.headerObj});
  }
}

您还可以选择传递整个对象，而不是在http.get()中指定headers参数。

const httpOptions = {
  headers: new HttpHeaders({
    'User-Agent' : 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.153 Safari/537.36'
  })
};

然后你就会回来：

return this.http.get<Weather>(this.serviceUrl, httpOptions);

我经常发现角文档有很好的例子-- 角HTTP指南-添加报头

Answer 3

基于文档，HttpClient.get的第一个参数是url，第二个参数是配置。

因此，您的代码应该如下所示：

export class NWSForecast {
  private config = {
    headers: {
      'User-Agent' : 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.153 Safari/537.36'
    }
  };

  private serviceUrl = 'https://api.weather.gov/gridpoints/OKX/36,38/forecast';

  constructor(private http: HttpClient) { }

  getUser(): Observable<any>  {
    // first argument is URL, put config as second argument
    return this.http.get<any>(this.serviceUrl, this.config);
  }
}

测试过它是否有效

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