在控制器中使用 [FromBody] 属性时，Blazor 服务器端应用程序（Razor 组件）中的 InputFormatters 为空

Question

我正在 Asp.Net Core 3.0 预览版中使用服务器端 blazor（Razor 组件）开发网页游戏。我有一个控制器 class 用于将游戏数据保存到服务器，但是每当我使用有效的 JSON 主体发出 post 请求时，控制器无法格式化请求正文，因为它无法从上下文中找到任何 IInputFormatter。

我已经能够在不使用 [FromBody] 属性的情况下执行简单的 GET 请求和 POST，所以我知道我的控制器路由正在工作。但是每当我尝试使用 HttpClient SendJsonAsync 或 PostJsonAsync 方法并尝试使用 [FromBody] 属性读取 JSON 时，我都会收到以下错误：

System.InvalidOperationException: 'Microsoft.AspNetCore.Mvc.MvcOptions.InputFormatters'不能为空。至少需要一个 'Microsoft.AspNetCore.Mvc.Formatters.IInputFormatter' 才能从正文中绑定。

我也直接安装了Microsoft.AspNetCore.Mvc.Formatters.Json到我的项目中，只是inn case，但运气不好。

我在 Server.Startup class

中注册并向我的服务添加了 mvc

// 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.AddRazorComponents<App.Startup>();
        services.AddMvc();

        //Register httpclient service
        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())
                };
            });
        }
    }

    // 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(routes => { routes.MapRoute(name: "default", template: "{controller}/{action}"); });
        app.UseRazorComponents<App.Startup>();
    }

我的控制器class和方法：

public class GameController : Controller
{        
    [HttpPost]
    [Route("api/Game/SaveGame")]
    public string SaveGame([FromBody]GameInfoBody gameInfo)
    {
         //save the game to database
    }
}

我的客户在我的 Game.cshtml 页面中致电：

public async Task<string> SaveGameToDatabase(GameEngine game)
{
    var request = new GameInfoPostModel()
    {
        gameInfo = new GameInfoBody
        {
            ID = game.ID,
            GameEngine = game,
            Players = game.Teams.SelectMany(x => x.Players).Select(x => new PlayerGameMapping() { PlayerID = x.ID }).ToList()
        }
    };

    try
    {
        var result = await Client.SendJsonAsync<string>(HttpMethod.Post, "/api/Game/SaveGame", request);
        return result;
    }
    catch (Exception e)
    {
        return "Failed to save" + e.Message;
    }
}

完整堆栈跟踪：

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)

阅读文档告诉我默认包含 JsonFormatters。我已使用 Fiddler 验证我的调用具有正确的内容类型和有效 JSON。我在想，如果它从上下文中找不到任何 InputFormatters，我一定没有正确配置服务，但我还没有发现其他人有这个问题，我不知道下一步该尝试什么。任何帮助将不胜感激，谢谢

Answer 1

试试这个：（按照这个顺序...）

services.AddMvc().AddNewtonsoftJson();

services.AddRazorComponents<App.Startup>();

在控制器中使用 [FromBody] 属性时，Blazor 服务器端应用程序（Razor 组件）中的 InputFormatters 为空

InputFormatters is empty in Blazor Server side Side app (Razor Components) when using [FromBody] attribute in controller

asp.net-core-webapi

blazor

blazor-server-side