Session & State Management

HTTP is a stateless protocol. By default, HTTP requests are independent messages that don't retain user values. In ASP.NET Core, state can be stored using several approaches.

Storage approach	Storage mechanism
Cookies	HTTP cookies. May include data stored using server-side app code.
Session state	HTTP cookies and server-side app code
TempData	HTTP cookies or session state
Query strings	HTTP query strings
Hidden fields	HTTP form fields
HttpContext.Items	Server-side app code
Cache	Server-side app code

TempData

This property stores data until it's read in another request. The Keep(String) and Peek(string) methods can be used to examine the data without deletion at the end of the request. TempData is:

• Useful for redirection when data is required for more than a single request.

• Implemented by TempData providers using either cookies or session state.

First Tab

public class CreateModel : PageModel
{
    private readonly RazorPagesContactsContext _context;

    public CreateModel(RazorPagesContactsContext context)
    {
        _context = context;
    }

    public IActionResult OnGet()
    {
        return Page();
    }

    [TempData]
    public string Message { get; set; }

    [BindProperty]
    public Customer Customer { get; set; }

    public async Task<IActionResult> OnPostAsync()
    {
        if (!ModelState.IsValid)
        {
            return Page();
        }

        _context.Customer.Add(Customer);
        await _context.SaveChangesAsync();
        Message = $"Customer {Customer.Name} added";

        return RedirectToPage("./IndexPeek");
    }
}

Second Tab

@page
@model IndexModel

<h1>Peek Contacts</h1>
@{
    if (TempData.Peek("Message") != null)
    {
        <h3>Message: @TempData.Peek("Message")</h3>
    }
}

@page
@model IndexModel

<h1>Contacts Keep</h1>
@{
    if (TempData["Message"] != null)
    {
        <h3>Message: @TempData["Message"]</h3>
    }
    TempData.Keep("Message");
}