asp.net核心中的TempData为空

Question

我正在尝试在 asp.net 核心中使用 TempData 但是我在 TempData 的 get 方法上得到一个空值。 任何人都可以让我知道如何在 asp.net core 中使用 TempData

以下是我根据研究添加的内容。

项目.json 文件

{
  "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 文件

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?}");
        });
    }

这是 tempdata 的实现。调用此方法时，我可以看到 TempData 中的值。

[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;
}

但是下面的方法在临时数据中具有空值。

[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;
}

这是调试会话的图像

Answer 1

编辑：

如https://docs.microsoft.com/en-us/aspnet/core/security/gdpr?view=aspnetcore-2.2#tempdata-provider-and-session-state-cookies-arent-essential 中所述，默认情况下 TempData cookie由 CookiePolicy 中间件删除。 这可以通过将其放入 Startup.ConfigureServices() 来更改：

// 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;
}); 

==============================================

旧答案：

迁移到 ASP Core 2.1 后，我遇到了这个问题，并在工作了一天后找到了解决方案：

\n

在 Startup.Configure() app.UseCookiePolicy(); 应该在 app.UseMVC();

Answer 2

官方文档中描述的中间件顺序没有问题，即：

1. 异常/错误处理
2. HTTP 严格传输安全协议
3. HTTPS 重定向
4. 静态文件服务器
5. Cookie 政策实施
6. 验证
7. 会议
8. MVC

但是，当我们使用 Cookie 策略执行 (UseCookiePolicy) 时，只有将发送到浏览器的必要cookie 和来自 Tempdata 提供程序的 Cookie不是必需的，因此出现问题。 所以我们必须根据官方文档使它变得必不可少：

Tempdata 提供程序 cookie 不是必需的。 如果禁用跟踪，则 Tempdata 提供程序不起作用。 要在禁用跟踪时启用 Tempdata 提供程序，请在 Startup.ConfigureServices 中将 TempData cookie 标记为必需

// 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;
});

添加这些行应该可以解决您的问题，而无需重新排序中间件。

Answer 3

请将您的所有软件包升级到相同的1.1.0版本并添加缓存服务。 这是在Asp.Net Core使用TempData所需的东西

项目.json

"Microsoft.AspNetCore.Session": "1.1.0"

这是 Startup.cs 文件。 - 配置服务方法

public void ConfigureServices(IServiceCollection services)
{
     services.AddMemoryCache();
     services.AddSession();
     services.AddMvc();
}

和配置方法。

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    app.UseSession();
        app.UseMvc(routes =>
        {
            routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
    });
}

现在尝试使用TempData ，它将起作用。

您可以使用 set ASPNETCORE_ENVIRONMENT=Development 环境变量设置环境。

聚苯乙烯

ASP.NET Core MVC在Controller上公开TempData属性。 TempData可用于存储仅需要在当前请求之后可用于单个请求的瞬态数据。

当读取TempDataDictionary的对象时，它将在该请求结束时标记为删除。

Peek和Keep方法允许您读取值而不将其标记为删除。 假设我们回到将值保存到TempData的第一个请求。

使用Peek您只需一次调用即可获得该值，而无需将其标记为删除。

//second request, PEEK value so it is not deleted at the end of the request
object value = TempData.Peek("value");

//third request, read value and mark it for deletion
object value = TempData["value"];

使用Keep您可以指定要保留的标记为删除的密钥。 检索对象并稍后将其从删除中保存是 2 个不同的调用。

//second request, get value marking it from deletion
object value = TempData["value"];
//later on decide to keep it
TempData.Keep("value");

//third request, read value and mark it for deletion
object value = TempData["value"];