3.0.0 preview 2 Razor Components: "InputFormatters" is empty when making Web API POST

[EricPalmer22]

With a new "Razor Components" project using .NET Core 3.0.0 preview 2, I am trying to make an Http call to a controller on the server to save game data to a SQLite database. But, any POST call that I to do to a controller method with a [FromBody] parameter attribute, I get the following error: `System.InvalidOperationException: 'Microsoft.AspNetCore.Mvc.MvcOptions.InputFormatters' must not be empty. At least one 'Microsoft.AspNetCore.Mvc.Formatters.IInputFormatter' is required to bind from the body.

I see that a JsonInputFormatter should be included by default when I register the MVC services, but for some reason there are no InputFormatters in the context.

To test this, I created a brand new Razor Components project under .NET Core 3.0.0 templates.
I registered MVC and HttpClient services on my Server.Startup class:

public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();
            
            if (!services.Any(x => x.ServiceType == typeof(HttpClient)))
            {
                // Setup HttpClient for server side in a client side compatible fashion
                services.AddScoped<HttpClient>(s =>
                {
                    // Creating the URI helper needs to wait until the JS Runtime is initialized, so defer it.
                    var uriHelper = s.GetRequiredService<IUriHelper>();
                    return new HttpClient
                    {
                        BaseAddress = new Uri(uriHelper.GetBaseUri())
                    };
                });
            }
            services.AddRazorComponents<App.Startup>();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            };
            app.UseMvc();
            app.UseStaticFiles();
            app.UseRazorComponents<App.Startup>();
        }
    }

I created a CounterController class on my Server with a simple test method:

public class CounterController : Controller
    {
        [HttpPost]
        [Route("/api/Counter/Test")]
        public void Test([FromBody]string value)
        {
            var test = value;
        }
    }

And updated the Counter.cshtml file to inject the Httpclient and make a call to our controller:

@page "/counter"
@using System.Net.Http;
@inject HttpClient Client

<h1>Counter</h1>

<p>Current count: @currentCount</p>

<button class="btn btn-primary" onclick="@IncrementCount">Click me</button>

@functions {
    int currentCount = 0;

    void IncrementCount()
    {
        currentCount++;
        var stringReq = new StringBody() { value = "test" };
        Client.PostJsonAsync("/api/Counter/Test", stringReq).Wait();
    }

    public class StringBody
    {
        public string value { get; set; }
    }
}

I can use [FromQuery] parameters and everything works fine, but I just cannot get sending JSON to work because of this error. I verified that the request is being made with the correct content type and the body is valid JSON. I'm also learning Blazor as I go here and don't have a solid background with MVC/Razor pages, so it's very possible I'm just doing something wrong. My goal is to have a web game that can persist game data to a database on the server. I figured I would have my EF dbcontext datalayer and my web api controller living on the server to accept client calls for saving/updating game state.

Full stacktrace:

System.InvalidOperationException: 'Microsoft.AspNetCore.Mvc.MvcOptions.InputFormatters' must not be empty. At least one 'Microsoft.AspNetCore.Mvc.Formatters.IInputFormatter' is required to bind from the body.
   at Microsoft.AspNetCore.Mvc.ModelBinding.Binders.BodyModelBinderProvider.GetBinder(ModelBinderProviderContext context)
   at Microsoft.AspNetCore.Mvc.ModelBinding.ModelBinderFactory.CreateBinderCoreUncached(DefaultModelBinderProviderContext providerContext, Object token)
   at Microsoft.AspNetCore.Mvc.ModelBinding.ModelBinderFactory.CreateBinder(ModelBinderFactoryContext context)
   at Microsoft.AspNetCore.Mvc.Controllers.ControllerBinderDelegateProvider.GetParameterBindingInfo(IModelBinderFactory modelBinderFactory, IModelMetadataProvider modelMetadataProvider, ControllerActionDescriptor actionDescriptor, MvcOptions mvcOptions)
   at Microsoft.AspNetCore.Mvc.Controllers.ControllerBinderDelegateProvider.CreateBinderDelegate(ParameterBinder parameterBinder, IModelBinderFactory modelBinderFactory, IModelMetadataProvider modelMetadataProvider, ControllerActionDescriptor actionDescriptor, MvcOptions mvcOptions)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvokerCache.GetCachedResult(ControllerContext controllerContext)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvokerProvider.OnProvidersExecuting(ActionInvokerProviderContext context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ActionInvokerFactory.CreateInvoker(ActionContext actionContext)
   at Microsoft.AspNetCore.Mvc.Routing.MvcEndpointDataSource.<>c__DisplayClass22_0.<CreateEndpoint>b__0(HttpContext context)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

[pranavkm]

We're in the midst of adding JSON formatters based on System.Text.Json. In the meanwhile you have to manually add back the JSON.NET based ones to your application.

1. Add a PackageReference to Microsoft.AspNetCore.Mvc.NewtonsoftJson - https://www.nuget.org/packages/Microsoft.AspNetCore.Mvc.NewtonsoftJson/3.0.0-preview-19075-0444
2. Change your ConfigureServices, services.AddMvc().AddNewtonsoftJson()

[EricPalmer22]

There it is, thank you!

[aktxyz]

the .AddNewtonsoftJson() approach is working ... but when trying to add a content-type to the json input formatter as shown below, the InputFormatters is empty during AddMvc config time, probably because it is not added until the .AddNewtonsoftJson()

any thought on how to work around this or if something else is wrong in the code below?

            services
                .AddMvc(options =>
                {
                    foreach (var formatter in options.InputFormatters)
                    {
                        if (formatter.GetType() == typeof(NewtonsoftJsonInputFormatter))
                            ((NewtonsoftJsonInputFormatter)formatter).SupportedMediaTypes.Add(
                                Microsoft.Net.Http.Headers.MediaTypeHeaderValue.Parse("text/plain"));
                    }
                })
                .AddNewtonsoftJson();

[endeffects]

@aktxyz

To fix the problem use:

            services.AddMvc().AddNewtonsoftJson().AddMvcOptions(e =>
            {
                e.InputFormatters.OfType<NewtonsoftJsonInputFormatter>().ToList().ForEach(formatter => formatter.SupportedMediaTypes.Add(MediaTypeHeaderValue.Parse("text/plain")));
            });

[aktxyz]

aha ... very very nice

[marcuslindblom]

What is the equivalent way of doing the following in preview 7 if I want to be able to ReadAsAsync without the need of adding my own formatters every time? Is it possible to add default supported mediatypes?

MediaTypeFormatterCollection formatters = new MediaTypeFormatterCollection();
formatters.JsonFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/vnd.xxx.v1+json"));                

TokenResponse token =  await tokenResponse.Content.ReadAsAsync<TokenResponse>(formatters);

[rynowak]

Hi, it looks like you are posting on a closed issue/PR/commit!

We're very likely to lose track of your bug/feedback/question unless you:

1. Open a new issue
2. Explain very clearly what you need help with
3. If you think you have found a bug, include detailed repro steps so that we can investigate the problem

Thanks!