asp.net核心中的TempData null

旧答案: 迁移到ASP Core 2.1之后，出现了此问题，并在工作了一天后找到了解决方案:在Startup.Configure()中app.UseCookiePolicy();应该在app.UseMVC();之后 I am trying to use TempData in asp.net core However I am getting a null value on the get method of TempData. Can anyone please let me know how can I use TempData in asp.net coreBelow are the things I, have added as per the research.Project.json file{ "dependencies": { "Microsoft.NETCore.App": { "version": "1.0.1", "type": "platform" }, "Microsoft.AspNetCore.Mvc": "1.0.1", "Microsoft.AspNetCore.Routing": "1.0.1", "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0", "Microsoft.AspNetCore.Server.Kestrel": "1.0.1", "Microsoft.Extensions.Configuration.EnvironmentVariables": "1.0.0", "Microsoft.Extensions.Configuration.FileExtensions": "1.0.0", "Microsoft.Extensions.Configuration.Json": "1.0.0", "Microsoft.Extensions.Logging": "1.1.0", "Microsoft.Extensions.Logging.Console": "1.0.0", "Microsoft.Extensions.Logging.Debug": "1.0.0", "Microsoft.Extensions.Options.ConfigurationExtensions": "1.0.0", "Microsoft.EntityFrameworkCore.SqlServer": "1.1.0", "Microsoft.EntityFrameworkCore.Tools": "1.1.0-preview4-final", "Microsoft.EntityFrameworkCore.Design": "1.1.0", "Microsoft.EntityFrameworkCore.SqlServer.Design": "1.1.0", "DataBase": "1.0.0-*", "UnitOfWork": "1.0.0-*", "ViewModel": "1.0.0-*", "Common": "1.0.0-*", "System.IdentityModel.Tokens.Jwt": "5.0.0", "Microsoft.AspNetCore.Authentication.JwtBearer": "1.0.0", "Microsoft.AspNetCore.Diagnostics": "1.0.0", "Microsoft.AspNetCore.StaticFiles": "1.0.0", "Microsoft.AspNetCore.Session": "1.1.0", "Microsoft.Extensions.Caching.Memory": "1.1.0" }, "tools": { "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final", "Microsoft.EntityFrameworkCore.Tools.DotNet": "1.0.0-preview3-final", "Microsoft.AspNetCore.Razor.Tools": "1.0.0-preview2-final" }, "frameworks": { "netcoreapp1.0": { "imports": [ "dotnet5.6", "portable-net45+win8" ] } }, "buildOptions": { "emitEntryPoint": true, "preserveCompilationContext": true }, "runtimeOptions": { "configProperties": { "System.GC.Server": true } }, "publishOptions": { "include": [ "wwwroot", "**/*.cshtml", "appsettings.json", "web.config" ] }, "scripts": { "postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ] }}start.cs filepublic void ConfigureServices(IServiceCollection services){ services.AddMemoryCache(); services.AddSession(); // Add framework services. services.AddMvc(); services.AddTransient<IMarketUOW, MarketUow>(); services.AddTransient<ICategoryUow, CategoryUow>(); services.AddTransient<IUserProfileUow, UserProfileUow>(); services.AddTransient<IItemUow, ItemUow>(); services.AddTransient(typeof(IGenericRepository<>), typeof(GenericRepository<>)); var connection = Configuration.GetConnectionString("DefaultConnection"); services.AddDbContext<EmakitiContext>(options => options.UseSqlServer(connection));}public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory){ app.UseSession(); app.UseMvc(routes => { routes.MapRoute( name: "default", template: "{controller=Home}/{action=Index}/{id?}"); }); }Here is the implementation of tempdata.When this method is called I can see the value in TempData.[HttpGet("{pageNumber}")]public GenericResponseObject<List<MarketViewModel>> GetMarketList(int pageNumber){ TempData["Currentpage"] = pageNumber; TempData.Keep("Currentpage"); GenericResponseObject<List<MarketViewModel>> genericResponseObject = new GenericResponseObject<List<MarketViewModel>>(); genericResponseObject.IsSuccess = false; genericResponseObject.Message = ConstaintStingValue.Tag_ConnectionFailed; try { var marketItem = _iMarketUow.GetMarketList(pageNumber); genericResponseObject.Data = marketItem.Item1; var totalPages = (int)Math.Ceiling((decimal)marketItem.Item2 / (decimal)10); genericResponseObject.TotalPage = totalPages; genericResponseObject.IsSuccess = true; genericResponseObject.Message = ConstaintStingValue.Tag_SuccessMessageRecord; genericResponseObject.Message = ConstaintStingValue.Tag_ConnectionSuccess; } catch (Exception exception) { genericResponseObject.IsSuccess = false; genericResponseObject.Message = exception.Message; genericResponseObject.ErrorCode = exception.HResult; genericResponseObject.ExceptionErrorMessage = exception.StackTrace; } return genericResponseObject;}But the below method has null value in the temp data.[HttpPost]public GenericResponseObject<List<MarketViewModel>> AddUpdateMarket([FromBody] MarketViewModel marketViewModel){ GenericResponseObject<List<MarketViewModel>> genericResponseObject = new GenericResponseObject<List<MarketViewModel>>(); genericResponseObject.IsSuccess = false; genericResponseObject.Message = ConstaintStingValue.Tag_ConnectionFailed; if (marketViewModel!= null && ModelState.IsValid) { try { _iMarketUow.AddUpdateMarketList(marketViewModel); genericResponseObject = GetMarketList(Convert.ToInt16(TempData.Peek("Currentpage"))); } catch (Exception exception) { genericResponseObject.IsSuccess = false; genericResponseObject.Message = exception.Message; genericResponseObject.ErrorCode = exception.HResult; genericResponseObject.ExceptionErrorMessage = exception.StackTrace; } } else { genericResponseObject.Message = ConstaintStingValue.Tag_InputDataFormatNotMatch; } return genericResponseObject;}Here is the image of the debug session 解决方案 Edited:As Described in https://docs.microsoft.com/en-us/aspnet/core/security/gdpr?view=aspnetcore-2.2#tempdata-provider-and-session-state-cookies-arent-essentialby default TempData cookies are removed by the CookiePolicy Middleware. this can be changed by putting this in Startup.ConfigureServices():// The TempData provider cookie is not essential. Make it essential// so TempData is functional when tracking is disabled.services.Configure<CookieTempDataProviderOptions>(options => { options.Cookie.IsEssential = true;});=============================================Old Answer:After Migrating to ASP Core 2.1 I had this issue and after working for a day find the solution:in Startup.Configure()app.UseCookiePolicy(); should be after app.UseMVC(); 这篇关于asp.net核心中的TempData null的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！