Angular 6：HttpHeaders无法在Chrome和IE11中读取null的属性“长度”（而不是在Firefox中）

问题描述

在我的 Angular6 应用下，我正在使用 HttpClient 向我的htpp调用注入一些标头来从我的后端服务器获取数据：

Under my Angular6 app , i'm using HttpClient with some headers injection to my htpp calls to fetch data from my backend server :

我的服务：

My service :

@Injectable()
export class LoadUserInfosService {

  public _headers = new HttpHeaders().set('Content-Type', 'application/json');

  constructor(private httpClient: HttpClient) {}

  getUserPnsInfos(cuid): Observable<object> {
    const headers = this._headers.append('login', login);
    return this.httpClient.get(myBackUrl, {headers: headers});
  }
}

我订阅的组件它：

loadUserInfosFromPns(login) {
    this.loadUserInfosService.getUserPnsInfos(login).subscribe(infos => {
      let receivedInfos: any;
        receivedPnsInfos = infos ;
        console.log(receivedPnsInfos);
        if (pnsInfos !== null && receivedPnsInfos.cuid === cuid ) {
        } else {
          this.router.navigate(['unauthorized'], {skipLocationChange: true});
        }
      },
      error => {
        console.log(error);
      });
  }

在Chrome或IE11上运行时我收到一些错误，提到我的请求header：

when running on Chrome or IE11 i'm getting some error refering to my request headers:

TypeError: Cannot read property 'length' of null
    at HttpHeaders.push../node_modules/@angular/common/fesm5/http.js.HttpHeaders.applyUpdate (http.js:199)
    at http.js:170
    at Array.forEach (<anonymous>)
    at HttpHeaders.push../node_modules/@angular/common/fesm5/http.js.HttpHeaders.init (http.js:170)
    at HttpHeaders.push../node_modules/@angular/common/fesm5/http.js.HttpHeaders.forEach (http.js:235)
    at Observable._subscribe (http.js:1445)
    at Observable.push../node_modules/rxjs/_esm5/internal/Observable.js.Observable.subscribe (Observable.js:161)
    at subscribeTo.js:21
    at subscribeToResult (subscribeToResult.js:6)
    at MergeMapSubscriber.push../node_modules/rxjs/_esm5/internal/operators/mergeMap.js.MergeMapSubscriber._innerSub (mergeMap.js:127)

此错误仅出现在 Chrome 和 IE11 中 - 在 Firefox 下 请求变好，我没有得到它

this error appears only in Chrome and IE11 - while under Firefox the request get well and i'm not getting it

有任何想法，建议吗？

推荐答案

这可能是因为您正在设置undefined / null标头在一些http请求中。

It is probably caused because you are settting an undefined / null header in some http request.

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