在.net Core Web API和angular 6中启用CORS

Question

Here I'm using an HTTP POST request from Angular 6 and it is hitting in the .net core Web API call, but I'm not getting the response output back to Angular 6 and in console got an error that:

"Access to XMLHttpRequest at ' http://localhost:55654/api/login/auth ' from origin ' http://localhost:4200 ' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource."

But I'm a bit confused that if it is any CORS enabling access issue, it won't hit the web API call. But it hits the API call and I'm not getting the response back.

Angular 6 HTTP POST request:

this.http.post("http://localhost:55654/api/login/auth", credentials, {
  headers: new HttpHeaders({
 "Content-Type": "application/json"
      })
  }).subscribe(response => {
      let token = (<any>response);
      localStorage.setItem("jwt", token);
    }, err => {

    });

I've enabled the CORS in following methods in .NetCore Web API

Configure Method in Startup.cs :

...
app.UseCors(options =>
  options.WithOrigins("http://localhost:4200")
    .AllowAnyMethod()
    .AllowAnyHeader());
 ...

ConfigureServices Method in Startup.cs :

...
services.AddCors();
...

Answer 1

On Startup.cs add in ConfigureServices:

services.AddCors();

On Configure add

app.UseCors(x => x.AllowAnyOrigin().AllowAnyMethod().AllowAnyHeader());

This solved your problem

Answer 2

I would suggest to add a Proxy to access your Backend. Just add an proxy-file (proxy.conf.json) to your root directory.

Serve your App with: ng s --proxy-config [PathToProxy]

For example:

{
  "/api/*": {
    "target": "http://localhost:55654",
    "secure": false,
    "logLevel": "debug"
  }
}

https://github.com/angular/angular-cli/blob/master/docs/documentation/stories/proxy.md

Answer 3

As mentioned in the comments:

The call to app.UseMvc needs to be AFTER app.UseCors

...
app.UseCors(options =>
  options.WithOrigins("http://localhost:4200")
    .AllowAnyMethod()
    .AllowAnyHeader());

app.UseMvc();
...