MapFallback catch all requests to API controller when ConsumeAttribute added

[Brainman643]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Hello.
In .net 6 behavior of MapFallback broke when ConsumesAttribute was added. MapFallback catch all requests to API controller.
In .net 6 index.html file always returns on requests to API controller but if I remove endpoints.MapFallbackToFile or delete ConsumesAttribute filter then everything works as I expected.
In .net 5 the example works correctly.

ConsumesAttribute was added for the correct generation of swagger.json by Swashbuckle in order not to add it to every action or controller.

Expected Behavior

Requests to controllers must not be catched by MapFallback.

Steps To Reproduce

    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers(options => options.Filters.Add(new ConsumesAttribute("application/json")));
        }
        public void Configure(IApplicationBuilder app)
        {
            app.UseRouting();
            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
                endpoints.MapFallbackToFile("index.html");
            });
        }
    }

Exceptions (if any)

No response

.NET Version

6.0.200

Anything else?

No response

[javiercn]

@Brainman643 thanks for contacting us.

Here is what is happening.

I believe this is a side-effect of moving the Consumes to be evaluated earlier (as part of route matching via a matcher policy) during the request processing pipeline.

On .NET 5.0 there wasn't any accept policy, so any endpoint with [Consumes] attribute would match even if the content-type from the header was incompatible with the endpoint. Later on, the Consumes filter would take effect and generate the expected 415 response.

On .NET 6.0 we added and registered an AcceptsMatcherPolicy by default to evaluate this during routing for minimal APIs. As a result of this, evaluating the compatibility with the content type has moved earlier in the request pipeline
and the endpoint is being discarded. Since the endpoint is being discarded, the fallback endpoint added for SPAs and Blazor Webassembly now gets selected instead.

You should be able to add this to your map fallback to file call to avoid the fallback from being matched in these situations

    endpoints.MapFallbackToFile("index.html").WithMetadata(new HttpMethodMetadata(new[] { "GET" }))

Thanks for contacting us.
We're moving this issue to the .NET 7 Planning milestone for future evaluation / consideration. Because it's not immediately obvious that this is a bug in our framework, we would like to keep this around to collect more feedback, which can later help us determine the impact of it. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[tnlthanzeel]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Hello. In .net 6 behavior of MapFallback broke when ConsumesAttribute was added. MapFallback catch all requests to API controller. In .net 6 index.html file always returns on requests to API controller but if I remove endpoints.MapFallbackToFile or delete ConsumesAttribute filter then everything works as I expected. In .net 5 the example works correctly.

ConsumesAttribute was added for the correct generation of swagger.json by Swashbuckle in order not to add it to every action or controller.

Expected Behavior

Requests to controllers must not be catched by MapFallback.

Steps To Reproduce

    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers(options => options.Filters.Add(new ConsumesAttribute("application/json")));
        }
        public void Configure(IApplicationBuilder app)
        {
            app.UseRouting();
            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
                endpoints.MapFallbackToFile("index.html");
            });
        }
    }

Exceptions (if any)

No response

.NET Version

6.0.200

Anything else?

No response

same issue for me too, is there a solution?

[tnlthanzeel]

@Brainman643 thanks for contacting us.

Here is what is happening.

I believe this is a side-effect of moving the Consumes to be evaluated earlier (as part of route matching via a matcher policy) during the request processing pipeline.

On .NET 5.0 there wasn't any accept policy, so any endpoint with [Consumes] attribute would match even if the content-type from the header was incompatible with the endpoint. Later on, the Consumes filter would take effect and generate the expected 415 response.

On .NET 6.0 we added and registered an AcceptsMatcherPolicy by default to evaluate this during routing for minimal APIs. As a result of this, evaluating the compatibility with the content type has moved earlier in the request pipeline and the endpoint is being discarded. Since the endpoint is being discarded, the fallback endpoint added for SPAs and Blazor Webassembly now gets selected instead.

You should be able to add this to your map fallback to file call to avoid the fallback from being matched in these situations

    endpoints.MapFallbackToFile("index.html").WithMetadata(new HttpMethodMetadata(new[] { "GET" }))

this solutioj doent work for me. is there anytging else to fix this?

[javiercn]

@Brainman643 can you explain what is not working for you in a separate issue?

(Include please a minimal repro project as a public gh repo).