我用 Angular 4 编写了一个应用程序。看起来每次我尝试访问 API 时,angular 都会发出 2 个请求。我的应用程序中的所有方法都会发生这种情况,包括;获取、删除、放置、发布
我将在下面添加一些代码示例。例如,我有一个 NotificationComponent,它列出了来自数据库的所有通知。 NotificationComponent 有一个方法可以在 ngOnInit
上加载通知;
this.NotificationService.All(AdditionalParams)
.subscribe(
notifications => {
this.AllNotifications.Notifications = notifications.data;
this.AllNotifications.Data = notifications;
this.AllNotifications.Loading = false;
this.AllNotifications.Loaded = true;
this.AllNotifications.HasRequestError = false;
},
(error)=> {
this.AllNotifications.Loading = false;
this.AllNotifications.Loaded = false;
this.AllNotifications.RequestStatus = error.status;
if (typeof error.json == 'function' && error.status!=0) {
let errorObject = error.json();
this.AllNotifications.RequestError = errorObject;
} else {
this.AllNotifications.RequestError = "net::ERR_CONNECTION_REFUSED";
}
this.AllNotifications.HasRequestError = true;
});
}
该方法订阅了在 NotificationService 中找到的 All 方法。 All 方法如下所示;
All(AdditionalParams: object): Observable<any> {
let options = new RequestOptions({ headers: this.headers });
let params = new URLSearchParams();
//params.set("token", this.authenticationService.token);
for (var key in AdditionalParams) {
params.set(key, AdditionalParams[key]);
}
options.params = params;
return this.http.get(this.notificationsUrl, options)
.map(response => response.json())
.catch(this.handleError);
}
不知何故请求被发送了两次。我认为这是在我的控制台日志中;
XHR finished loading: GET "[REMOVED]/notifications?page=1&event=1&token=eyJ0eXAiOi…GkiOiJ1bGYxSnJPa1Zya0M2NmxDIn0.3kA8Pd-tmOo4jUinJqcDeUy7mDPdgWpZkqd3tbs2c8A"
XHR finished loading: GET "[REMOVED]/notifications?page=1&event=1&token=eyJ0eXAiOi…GkiOiJ1bGYxSnJPa1Zya0M2NmxDIn0.3kA8Pd-tmOo4jUinJqcDeUy7mDPdgWpZkqd3tbs2c8A"
大约相隔 3 秒。
我有一个名为“AuthenticationService”的服务。在此服务中,我使用 ng-http-interceptor 添加了一个 http 拦截器。 http拦截器被添加到所有请求中。它看起来像这样;
httpInterceptor.request().addInterceptor((data, method) => {
console.log ("Before httpInterceptor: ", data);
var RequestOptionsIndex = null;
for (var _i = 0; _i < data.length; _i++) {
if (typeof data[_i] == 'object' && data[_i].hasOwnProperty('headers')){
RequestOptionsIndex = _i;
}
}
if (RequestOptionsIndex == null) {
let options = new RequestOptions({headers: new Headers({'Content-Type': 'application/json'})});
let params = new URLSearchParams();
data.push(options);
RequestOptionsIndex = data.length-1;
}
//console.log (data, this.loginURL, 'RequestOptionsIndex: ', RequestOptionsIndex);
if (!data[RequestOptionsIndex].hasOwnProperty('headers')){
data[RequestOptionsIndex].headers = new Headers({'Content-Type': 'application/json'});
}
if (data[0]!=this.loginURL && (data[RequestOptionsIndex].headers.get('Authorization')=="" || data[RequestOptionsIndex].headers.get('Authorization')==null)) {
data[RequestOptionsIndex].headers.append("Authorization", 'Bearer ' + this.token);
}
if (data[RequestOptionsIndex].params!=undefined && data[RequestOptionsIndex].params!=null) {
data[RequestOptionsIndex].params.set('token', this.token);
}else {
let params = new URLSearchParams();
params.set('token', this.token);
data[RequestOptionsIndex].params = params;
}
console.log ("httpInterceptor data", data, ": RequestOptionsIndex", RequestOptionsIndex);
return data;
});
httpInterceptor.response().addInterceptor((res, method) => {
res.map(response => response.json())
.catch((err: Response, caught: Observable<any>) => {
if (err.status === 401) {
this.logout();
this.router.navigate(["/login"]);
location.reload();
return Observable.throw("401 Unauthorized");
}
return Observable.throw(caught); // <-----
}).subscribe()
return res;
});
最佳答案
在发布问题时,我注意到我订阅了我的 httpInterceptor.response().addInterceptor
中的响应,删除 .subscribe()
修复了它。于是就变成了;
httpInterceptor.response().addInterceptor((res, method) => {
return res.map(response => response) // => response.json()
.catch((err: Response, caught: Observable<any>) => {
if (err.status === 401) {
this.logout();
this.router.navigate(["/login"]);
location.reload();
return Observable.throw("401 Unauthorized");
}
return Observable.throw(caught); // <-----
})//.share().subscribe()
//return res;
});
以防万一有人犯这样的愚蠢错误。这是我的解决方案。
当您多次订阅请求时会出现问题,因此它会被执行多次。解决方案是共享请求或订阅一次。我不确定在不重新加载的情况下共享请求多个订阅的确切方法,希望有人会确认这一点。我尝试了 .share().subscribe()
但似乎对我不起作用。
关于javascript - Angular 两次发送 http 请求,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/45534491/