Blazor routing fails when a query string is present

[balintn22]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I have a Blazor web app with an index page at the route "/".

When accessed through myhost/myapp everything works fine. However, I published the url in a Facebook post and when users tap that link FB appends a query parameter called fbclid - making the Blazor app fail.

The error message I get in the web server logs is "The URI 'http://myhost/myapp?fbclid=[...]' is not contained by the base URI 'http://myhost/myapp/'."

My Blazor page was like this:

@page "/"
<PageTitle>Index</PageTitle>
<h1>Welcome!</h1>

To handle the issue, I tried adding a query argument like this:

@page "/"
<PageTitle>Index</PageTitle>
<h1>Welcome!</h1>

@code {
    [Parameter]
    [SupplyParameterFromQuery(Name = "fbclid")]
    public string FacebookClientId { get; set; }
}

... but the error remains.

I tried various URL's to access the page:

• http://myhost/myapp
  displays the page as expected
• http://myhost/myapp?fbclid=123
  produces the error
• http://myhost/myapp/?fbclid=123
  displays the page as expected - notice the superfluous '/' character before the '?'

Hosting environment:

• IIS 7.5 (Windows 7)
• .NET Core Hosting Bundle
• Used VS File deploy to copy files to IIS
• Used IIS Manager to Convert [Directory] to application

Can not reproduce the isue on dev environemnt with VS and IIS express, where the default utl is localhost:7801, as the browser auto-inserts a slash before the question mark.

Expected Behavior

• http://myhost/myapp?fbclid=123
  Should display the page without an error.

Steps To Reproduce

https://github.com/balintn22/BlazorApp1

• This is a result of creating a new project using the Visual Studio Blazor Web Server App template.
• Deploy to IIS
• Browse to the main page
• Append "?anyarg=anyvalue" to the url and reload

Exceptions (if any)

Category: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware
EventId: 1
SpanId: be0b764e7346a06b
TraceId: 8686d0b717b40edc25ffc5ac2426f609
ParentId: 0000000000000000
RequestId: 800018a2-0000-ee00-b63f-84710c7967bb
RequestPath: /regattasearch
ActionId: 1a3bb4fc-e879-410a-ae02-d37122926a4b
ActionName: /_Host

An unhandled exception has occurred while executing the request.

Exception:
System.ArgumentException: The URI 'http://myhost/myapp?fbclid=123' is not contained by the base URI 'http://myhost/myapp/'.
at Microsoft.AspNetCore.Components.NavigationManager.Validate(Uri baseUri, String uri)
at Microsoft.AspNetCore.Components.NavigationManager.Initialize(String baseUri, String uri)
at Microsoft.AspNetCore.Components.Server.Circuits.RemoteNavigationManager.Initialize(String baseUri, String uri)
at Microsoft.AspNetCore.Mvc.ViewFeatures.StaticComponentRenderer.g__InitializeCore|5_0(HttpContext httpContext)
at Microsoft.AspNetCore.Mvc.ViewFeatures.StaticComponentRenderer.PrerenderComponentAsync(ParameterView parameters, HttpContext httpContext, Type componentType)
at Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.PrerenderedServerComponentAsync(HttpContext context, ServerComponentInvocationSequence invocationId, Type type, ParameterView parametersCollection)
at Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.RenderComponentAsync(ViewContext viewContext, Type componentType, RenderMode renderMode, Object parameters)
at Microsoft.AspNetCore.Mvc.TagHelpers.ComponentTagHelper.ProcessAsync(TagHelperContext context, TagHelperOutput output)
at Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner.g__Awaited|0_0(Task task, TagHelperExecutionContext executionContext, Int32 i, Int32 count)
at RegattaSearch.WebUI.BlazorServer.Pages.Pages__Host.ExecuteAsync() in C:_Src\Balint\RegattaSearch\RegattaSearch\RegattaSearch.WebUI.BlazorServer\Pages_Host.cshtml:line 8
at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageCoreAsync(IRazorPage page, ViewContext context)
at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageAsync(IRazorPage page, ViewContext context, Boolean invokeViewStarts)
at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context)
at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable1 statusCode) at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable1 statusCode)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|30_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|25_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Routing.EndpointMiddleware.g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)

.NET Version

dotnet6

Anything else?

In the dev environment
VS 2022, 17.9.5
Windows 10 Pro
the issue does not occur: on executing the web app, the browser appears tih the URL and the custom port. When I enter a query string, the browser inserts a '/' character in front of the '?'.

[javiercn]

@balintn22 thanks for contacting us.

That seems to be an issue with the logic in the facebook app improperly concatenating the query string. Note that .../myapp is different from .../myapp/ in terms of browser and HTML semantics, so we simply can't accept .../myapp as that will introduce problems with how many things in the document are processed. (The base path for .../myapp is ..., as opposed to .../myapp/ for .../myapp/).

One way you can solve this is by having a middleware on the server (or some code on the client) that detects the .../myapp path and redirects to .../myapp/ preserving the query string.

[balintn22]

I'm happy to understand that is it the way things are in Blazor route matching, what I don't understand is that an address like this
http://host/path?query
is a valid URL, a Blazor web app should be able to parse it.
The default web app generated by VS using the template should generate code that accepted this valid URL.
I should be able to write a Blazor app that can accept such a valid URL.
If this is not the case, it is a bug in Blazor.
Am I missing something?
Reading through the anser I don't know how to change my app. My base route is "/". Can I change it in some way to accept urls without a trailing "/"?

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