我丢失了什么导致[TempData]装饰的属性从获取到发布不保留值? [英] What am I missing that causes [TempData] decorated property not to retain value from get to post?

问题描述

我对asp.net核心中的TempData属性的理解是，它将模型属性标记为需要在帖子和同一页面之间保持值不变(并且寿命可能更长，但至少要更长).

My understanding of the TempData attribute in asp.net core is that it marks a model property as needing to persist in value between posts and gets of same page (and possibly wider lifetime than that, but at least that).

我的问题是，当用户回发表单时，我已将其标记为TempData并在OnGetAsync中成功设置的任何属性都已重置为null.为什么会这样?

My issue is that any property I have marked as TempData and set successfully in OnGetAsync has been reset to null by the time user posts back the form. Why might that be?

还是我误解了TempData作为属性应该做什么?如果有的话，实现我正在尝试的最佳方法是什么?将电话号码传递到视图，然后将其重新发布回OnPostAsync?！?

Or have I misunderstood what TempData is supposed to do as an attribute? If I have, what's the best way to acheive what I'm trying to do? Pass the phone number to the view and then post it back to OnPostAsync?!?

public class MyPageModel : PageModel
{
    [TempData] public string PhoneNumber { get; set; }

    public async Task<IActionResult> OnGetAsync(string phoneNumber)
    {
       PhoneNumber = phoneNumber; //THIS IS WORKING
       return Page();
    }

    public async Task<IActionResult> OnPostAsync()
    {
         user.PhoneNumber = PhoneNumber; //BUT BY HERE PHONENUMBER is NULL?
    }
}

///在Startup.ConfigureServices中//我添加了以前没有的CookieTempDataProvider，但是我相信默认情况下启用了CookieTempDataProvider:

//In Startup.ConfigureServices // I added the CookieTempDataProvider which I did'nt have before, but I believe that CookieTempDataProvider is enabled by default: https://docs.microsoft.com/en-us/aspnet/core/fundamentals/app-state?view=aspnetcore-2.1#tempdata

services.AddSingleton<ITempDataProvider, CookieTempDataProvider>();
services.AddSession(options =>
        {
            //// Set a short timeout for easy testing.
            //options.IdleTimeout = TimeSpan.FromSeconds(10);
            options.Cookie.HttpOnly = true;
        });

有想法吗?！

推荐答案

好，我终于明白了我的问题所在.我有CookiePolicyOptions选项.即使我已取出CookieConsentPartial视图，CheckConsentNeeded lambda仍然存在.因此，我以为提供TempData支持的cookie未被设置，因为实际上我没有同意它们.

OK I finally see what my problem was. I had the CookiePolicyOptions options.CheckConsentNeeded lambda still in place, even though I had taken out the CookieConsentPartial view. So, I assume that the cookies that provided the backing for TempData were not getting set because effectively, I had not consented to them.

作为参考，整理完以下内容后，我的Configure或ConfigureServices中不需要任何与TempData或Cookie相关的内容.因为根据会话和应用程序状态在ASP.NET Core中文章:

For reference, after sorting out the below, I did not need to have ANYTHING TempData or Cookie related in my Configure or ConfigureServices. Because as per Session and app state in ASP.NET Core article:

在ASP.NET Core 2.0或更高版本中，默认情况下使用基于cookie的TempData提供程序将TempData存储在cookie中.

In ASP.NET Core 2.0 or later, the cookie-based TempData provider is used by default to store TempData in cookies.

        services.Configure<CookiePolicyOptions>(options =>
        {
            // This lambda determines whether user consent for non-essential cookies is needed for a given request.
           // options.CheckConsentNeeded = context => true; // WORKED FINE WHEN I COMMENTED IT OUT.  DID NOT WORK WHEN COMMENTED IN.
            options.MinimumSameSitePolicy = SameSiteMode.None;
        });

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