Blazor SSR Finally Gets TempData in .NET 11

If you have built Blazor static SSR apps, you have almost certainly hit the same wall: after a form POST that redirects, there is no built-in way to pass a one-time message to the next page. MVC and Razor Pages had TempData for over a decade. Blazor SSR did not, until .NET 11 Preview 2.

How TempData works in Blazor SSR

When you call AddRazorComponents() in your Program.cs, TempData is registered automatically. No extra service wiring. Inside any static SSR component, grab it as a cascading parameter:

@code {
    [CascadingParameter]
    public ITempData? TempData { get; set; }

    private void HandleSubmit()
    {
        // Store a flash message before redirecting
        TempData?.Set("StatusMessage", "Record saved.");
        Navigation.NavigateTo("/dashboard", forceLoad: true);
    }
}

On the target page, read the value. Once you call Get, the entry is removed from the store:

@code {
    [CascadingParameter]
    public ITempData? TempData { get; set; }

    private string? StatusMessage;

    protected override void OnInitialized()
    {
        StatusMessage = TempData?.Get<string>("StatusMessage");
    }
}

That is the classic Post-Redirect-Get pattern, and it now works in Blazor SSR with no custom state management.

Peek and Keep

ITempData provides four methods that mirror the MVC TempData lifecycle:

• Get<T>(key) reads the value and marks it for deletion.
• Peek<T>(key) reads without marking, so the value survives to the next request.
• Keep() retains all values.
• Keep(key) retains a specific value.

These give you control over whether a flash message disappears after one read or sticks around for a second redirect.

Storage providers

By default, TempData is cookie-based via CookieTempDataProvider. Values are encrypted with ASP.NET Core Data Protection, so you get tamper protection out of the box. If you prefer server-side storage, swap in SessionStorageTempDataProvider:

builder.Services.AddSession();
builder.Services
    .AddSingleton<ITempDataProvider, SessionStorageTempDataProvider>();

The catch: static SSR only

TempData does not work with interactive Blazor Server or Blazor WebAssembly render modes. It is scoped to static SSR, where each navigation is a full HTTP request. For interactive scenarios, PersistentComponentState or your own cascading state remain the right tools.

This is a small addition, but it removes one of the common “why can’t Blazor do what Razor Pages can?” complaints. Grab .NET 11 Preview 2 and try it in your next SSR form flow.