How to Enable Cors in .net standard API ( or .net core API) for PUT GET and DELETE Methods

 Error:

Access to fetch at 'https://localhost:44340/api/employee' from origin 'https://localhost:44339' has been blocked by CORS policy: Method PUT is not allowed by Access-Control-Allow-Methods in preflight response.

:44340/api/employee:1 Failed to load resource: net::ERR_FAILED

blazor.webassembly.js:1 crit: Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]

      Unhandled exception rendering component: TypeError: Failed to fetch

WebAssembly.JSException: TypeError: Failed to fetch

  at System.Net.Http.WebAssemblyHttpHandler.doFetch (System.Threading.Tasks.TaskCompletionSource`1[TResult] tcs, System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) <0x2fcb610 + 0x00a30> in <filename unknown>:0 

  at System.Net.Http.WebAssemblyHttpHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) <0x2f9dd40 + 0x00174> in <filename unknown>:0 

  at Microsoft.Extensions.Http.Logging.LoggingHttpMessageHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) <0x2f98030 + 0x00160> in <filename unknown>:0 

  at Microsoft.Extensions.Http.Logging.LoggingScopeHttpMessageHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) <0x2f71090 + 0x00182> in <filename unknown>:0 

  at System.Net.Http.HttpClient.FinishSendAsyncBuffered (System.Threading.Tasks.Task`1[TResult] sendTask, System.Net.Http.HttpRequestMessage request, System.Threading.CancellationTokenSource cts, System.Boolean disposeCts) <0x3394518 + 0x00278> in <filename unknown>:0 

  at sanjeebblazorapp.App.Services.EmployeeDataService.UpdateEmployee (sanjeebblazorapp.Shared.Employee employee) [0x00051] in C:\Users\sanje\source\repos\sanjeebko\sanjeebtutorial-blazor\sanjeebblazorapp.App\sanjeebblazorapp.App\Services\EmployeeDataService.cs:42 

  at sanjeebblazorapp.App.Pages.EmployeeEdit.HandleValidSubmit () [0x001b0] in C:\Users\sanje\source\repos\sanjeebko\sanjeebtutorial-blazor\sanjeebblazorapp.App\sanjeebblazorapp.App\Pages\EmployeeEdit.cs:81 

  at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion (System.Threading.Tasks.Task task) <0x3395450 + 0x000da> in <filename unknown>:0 

  at Microsoft.AspNetCore.Components.Forms.EditForm.HandleSubmitAsync () <0x3307b00 + 0x00218> in <filename unknown>:0 

  at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion (System.Threading.Tasks.Task task) <0x3395450 + 0x000da> in <filename unknown>:0 

  at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask (System.Threading.Tasks.Task taskToHandle) <0x2fb1590 + 0x000b6> in <filename unknown>:0 

Solution:

TO enable cors in .net core web API, cors policy need to be added in the services. Below code in blue color needs to be added in the Startup.cs file

public void ConfigureServices(IServiceCollection services)

        {

            

            services.AddDbContext<AppDbContext>(options =>

                options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

   

            services.AddCors(options =>

            {

                options.AddPolicy("Open", builder => builder.AllowAnyOrigin().AllowAnyHeader().WithMethods("PUT","DELETE","GET"));

            });

            services.AddControllers(); 

        }

 public void Configure(IApplicationBuilder app, IWebHostEnvironment env)

        {

            if (env.IsDevelopment())

            {

                app.UseDeveloperExceptionPage();

            }

            app.UseHttpsRedirection();

            app.UseRouting();

            app.UseAuthorization();

            app.UseCors("Open");

            app.UseEndpoints(endpoints =>

            {

                endpoints.MapControllers();

            });

        }