Recover Data Redirectaction mvc#

Question

I have a student consultation,

// POST: /Admin/Anuncio
    [HttpPost]
    public ActionResult Index(Estudante estudante)
    {
        if (ModelState.IsValid)
        {
            List<EstudantesEncontrados> list = GetEstudante(GetEstudanteProximo(estudante));

            if (list != null)
            {
                TempData["ListaEstudantesEncontrados"] = list;
                return RedirectToAction("Lista", "Busca");

            }
            else
            {
                ModelState.AddModelError("", "Erro Ao pesquisar");
            }

        }

        // If we got this far, something failed, redisplay form
        return View();

    }

if you find students redirects to the list of students found, when I refresh the page in the list of students it gives an error in the view because the Tempdata["Student Listfound"] that sends the MODEL is coming null from the above action, someone could help me?

I wonder if there is any way when it is updated the browser it takes the data that was sent in the form previously.

public ActionResult Lista()
    {
        ViewBag.Message = "";

        if (ModelState.IsValid)
        {
            if (TempData["ListaEstudantesEncontrados"] != null)
            {
                var model = TempData["ListaEstudantesEncontrados"] as List<EstudantesEncontrados>;
                return View(model); ;
            }
            else
            {
                ModelState.AddModelError("", "Erro ao consultar");
                return RedirectToAction("Index", "Home"});
            }
        }else{
            return RedirectToAction("Index", "Home");
        }           

    }

Answer 1

The Gypsy warned very well, really send your collection to the View using Tempdata is not the right way.

As he suggested, it is interesting, but an important observation: "your View needs to be typed, that is, of the type Student".

Tempdata is quite useful to display temporary messages such as success messages after a registration, for example:

Controler:

public class EstudanteController : Controller
{ 
    [HttpPost]
    public ActionResult Salvar()
    {
         //Código para salvar um Estudante.
         TempData["mensagem"] = "Mensagem de sucesso";
         return RedirectToAction("Index");
    }
}

View: (Index)

@model EstudanteViewModel   

<div>
    @TempData["mensagem"]
</div>

//Código restante...

After being redirected to the Index view, the Tempdata message is displayed.

Answer 2

This code is very wrong. TempData should not be used to send information from a survey to the View.

Create a ViewModel for the Student:

Viewmodels Estudanteviewmodel

public class EstudanteViewModel {
    /* Coloque aqui properties que vão corresponder aos parâmetros em tela */

    public virtual IList<Estudante> EstudantesEncontrados {get;set;}
}

In Controller, modify the following:

// POST: /Anuncios/Index
[AcceptVerbs(HttpVerbs.Post | HttpVerbs.Get)]
public ActionResult Index(EstudanteViewModel viewModel = null)
{
    if (viewModel != null && ModelState.IsValid)
    {
        var list = GetEstudante(GetEstudanteProximo(estudante));

        if (list != null)
        {
            viewModel.EstudantesEncontrados = list;
            return View(viewModel);
        }
        else
        {
            ModelState.AddModelError("", "Erro Ao pesquisar");
        }

    }

    return View(new EstudantesViewModel());
}

So you send an object EstudanteViewModel completed for the Controller and can search for it. If this object is not properly filled in, it displays a View empty.

Thus, the Action Lista is no longer required, since you can use the ViewModel to display your results on screen.