MVC Net Core Can TempData store Enumerables?

Question

Running this Index controller gives me errors, when I try to pass IEnumerable into Tempdata.

When debugging, TempData["ProductCategory"] seems to store expected data in Watch, but cannot render Html View after storing. However, the Html does show when I store a simple stirng.

    public IActionResult Index()
    {
        // This gives me http error 500
        //TempData["ProductCategory"] = productcategoryrepository.GetAllProductCategory();

        // This works at least!
        TempData["ProductCategory"] = "test"; 
        //TempData.Keep();
        return View();
    }

    public IEnumerable<ProductCategory> GetAllProductCategory()
    {
        return _context.ProductCategory.ToList();
    }

Other Info:

public partial class ProductCategory
{

    public ProductCategory()
    {
        Product = new HashSet<Product>();
    }
    public int ProductCategoryId { get; set; }
    public string ProductCategoryName { get; set; }
    public string ProductCategoryDescription { get; set; }

    public virtual ICollection<Product> Product { get; set; }
}

public partial class Product
{
    public int ProductId { get; set; }
    public string ProductName { get; set; }
    public string ProductDescription { get; set; }
    public string ImageLocation { get; set; }

    public int? ProductCategoryId { get; set; }
    public virtual ProductCategory ProductCategory { get; set; }
}

Answer 1

To be able to store data in sessions or temp data, the type must be serializable. IEnumerable<T> cannot be serialized. Try a List<T> instead.

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/app-state?view=aspnetcore-2.1