TempData null in asp.net core

Question

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 core

Below 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 file

public 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

Answer 1

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-essential by 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();