Angular 7 .NET Core 2 POST请求

Question

我正在构建一个.Net Core Api，它将被Angular 7客户端使用，但是由于任何原因，我对每个POST请求都有2个请求

createRole(role: RoleModel): any {
      return this.httpClient.post(this.appConfig.apiUrlRole, JSON.stringify(role), { headers: new HttpHeaders({ 'Content-Type': 'application/json' }) });
  }

控制器：

[HttpPost]
    public async Task<IActionResult> PostAsync([FromBody]RoleRecord roleRecord)
    {
        await _roleRecordService.InsertAsync(roleRecord);
        return Ok();
    }

Startup.cs

public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc();
        services.AddCors();
        services.AddCors(options =>
        {
            options.AddPolicy("CorsPolicy",
                builder => builder.AllowAnyOrigin()
                .AllowAnyMethod()
                .AllowAnyHeader()
                .AllowCredentials());
        });
        ..
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
       ....

        app.UseCorsMiddleware();
        app.UseMvc();
        //app.UseCors("CorsPolicy");
    }
}

谢谢