Blazor EditForm Enhance=True with StreamRendering

[Miroslav Holec]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe the problem.

When the user submits a form that takes a long time to process, it is advisable to provide feedback and set the submit button as disabled.

I tried to achieve this by combining enhanced forms together with enabled StreamRendering, but the processing always ended with an error warning that an attempt was being made to set HTTP headers for the ongoing response.

Login.razor

@attribute [StreamRendering]
<EditForm Enhance="true" Model="Input" method="post" OnValidSubmit="LoginUser" FormName="login">
....

Code Behind

private async Task LoginUser()
    {
        var result = await SignInManager.PasswordSignInAsync(Input.Email, Input.Password, true, lockoutOnFailure: false);

        if (result.Succeeded)
        {
            NavigationManager.NavigateTo("/premium");
            return;
        }

Error

System.InvalidOperationException: Headers are read-only, response has already started.
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpHeaders.ThrowHeadersReadOnlyException()
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpResponseHeaders.Microsoft.AspNetCore.Http.IHeaderDictionary.set_SetCookie(StringValues value)
   at Microsoft.AspNetCore.Http.ResponseCookies.Append(String key, String value, CookieOptions options)
   at Microsoft.AspNetCore.CookiePolicy.ResponseCookiesWrapper.Append(String key, String value, CookieOptions options)
   at Microsoft.AspNetCore.Authentication.Cookies.ChunkingCookieManager.AppendResponseCookie(HttpContext context, String key, String value, CookieOptions options)
   at Microsoft.AspNetCore.Authentication.Cookies.CookieAuthenticationHandler.HandleSignInAsync(ClaimsPrincipal user, AuthenticationProperties properties)
   at Microsoft.AspNetCore.Authentication.AuthenticationService.SignInAsync(HttpContext context, String scheme, ClaimsPrincipal principal, AuthenticationProperties properties)
   at Microsoft.AspNetCore.Identity.SignInManager`1.SignInWithClaimsAsync(TUser user, AuthenticationProperties authenticationProperties, IEnumerable`1 additionalClaims)
   at Microsoft.AspNetCore.Identity.SignInManager`1.SignInOrTwoFactorAsync(TUser user, Boolean isPersistent, String loginProvider, Boolean bypassTwoFactor)
   at Microsoft.AspNetCore.Identity.SignInManager`1.PasswordSignInAsync(TUser user, String password, Boolean isPersistent, Boolean lockoutOnFailure)
   at Microsoft.AspNetCore.Identity.SignInManager`1.PasswordSignInAsync(String userName, String password, Boolean isPersistent, Boolean lockoutOnFailure)
   at Holec.Web.Components.Pages.Identity.Login.LoginUser() in /Users/mholec/Repository/WWW/WWW-MiroslavHolec/Holec.Web/Components/Pages/Identity/Login.razor.cs:line 31
   at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
   at Microsoft.AspNetCore.Components.Forms.EditForm.HandleSubmitAsync()
   at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)
   at Microsoft.AspNetCore.Components.HtmlRendering.Infrastructure.StaticHtmlRenderer.HandleException(Exception exception)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.HandleExceptionViaErrorBoundary(Exception error, ComponentState errorSourceOrNull)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.<WaitForQuiescence>g__ProcessAsynchronousWork|54_0()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.WaitForQuiescence()
   at Microsoft.AspNetCore.Components.Endpoints.EndpointHtmlRenderer.SendStreamingUpdatesAsync(HttpContext httpContext, Task untilTaskCompleted, TextWriter writer)

Describe the solution you'd like

Overall, I think this scenario should by supported, because it allows to change

during processing POST request.

@attribute [StreamRendering]
<EditForm Enhance="true"....

Additional context

No response

[Artak]

Thanks for contacting us. The problem is really about what specific action you're trying to take after the Streaming rendering has started. If the action (in your case it's SignInManager.PasswordSignInAsync) tries to set a cookie or any other headers, that will not be possible.