使用 HttpClient 在点击发布请求时触发的两个调用 [英] Two calls triggering on click of post request using HttpClient

问题描述

在代码中添加标头后发生重复调用.找到图像以查看呼叫发生了两次.

auth-interceptor.ts

导出类AuthInterceptor实现HttpInterceptor{

intercept(req: HttpRequest
参考此处.
After adding headers inside code duplicate call is happening. find the image to see the call happening twice.

auth-interceptor.ts 

export class AuthInterceptor implements HttpInterceptor {
intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

    const clonedRequest = req.clone({
        headers: req.headers.set('X-CustomAuthHeader', 'some-auth-token')
    });

    console.log("new headers", clonedRequest.headers.keys());

    return next.handle(clonedRequest);
}
}

Please fine calls log image here..

call log 1

call log 2
解决方案
This type of request is called Preflighted requests that corresponds to a negotiation between the caller and the Web application based on HTTP headers. 

It consists of two phases:

The browser executes an OPTIONS request with the same URL as the target request to check that it has the rights to execute the request. This OPTIONS request returns headers that identify what is possible to do for the URL. 
If rights match, the browser executes the request.


Reference here.

                        
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