ASP . NET MVC 5 - Dropdownlist with Modelstate?

Question

I am developing a registration system using MVC5 with DAO, but there were some doubts that I could not resolve.

I have a table where I register Projects and another one where the types of Projects are:

Table: Projects

Campos:

• Projectoid
• Projectionist
• Projectoid

Table: Projectotpo

Campos:

• Projectoid
• Projectonome

I need to show in my view one DropDownList with all projects for the user to select (in the registration). And I also need to bring these Project Types in the Edit Project page, so that the previously registered value is selected.

After some researches I was able to make it work, but not in the way I would like that the code is currently like this:

(Projectocontroller)

//Controller GET: Projeto/Edit/5
public ActionResult Editar(int id)
{
    //Pesquisar projeto selecionado
    ProjetoDAO proj_dao = new ProjetoDAO();
    Projeto proj = proj_dao.listById(id);

    //Pesquisar todos os TIPOS de projetos
    ProjetoTipoDAO proj_tipo_dao = new ProjetoTipoDAO();
    List<ProjetoTipo> lista_projetotipo = proj_tipo_dao.ListAll();

    //Lista de SelectListItem
    List<SelectListItem> lista_ddl = new List<SelectListItem>();

    //Percorrer lista de Tipos de Projetos e adicionar na lista de SelectListItem
    bool selected = false;
    foreach (var item in lista_projetotipo)
    {
        //Checar se é o ID selecionado
        selected = (proj.ProjTipoId.ToString().Equals(item.ProjTipoId.ToString()));

        //Adicionar item na lista
        lista_ddl.Add(
            new SelectListItem()
            {
                Text = item.ProjTipoNome,
                Value = item.ProjTipoId,
                Selected = selected
            });
    }

    //Enviando a lista de Tipos de Projetos para a view através de ViewBag
    ViewBag.ListaTiposProjeto = lista_ddl;
}

(Edit.cshtml)

<div class="row">
    <div class="form-group">
        <div class="col-md-2">
            @Html.LabelFor(model => model.ProjTipo, 
                 new { @class = "control-label" })
        </div>
        <div class="col-md-10">
            @Html.DropDownList("ListaTiposProjeto", null, 
              "Selecione um item", new { @class = "form-control" })
        </div>
    </div>
</div>

That way, I can display the data on DropDownList and also bring it selected on the edit page, but I can not use the ModelState to validate the form.

• How I would do the same thing using the @Html.DropDownListFor<>?
• This would be the way? , because I followed some tutorials and did not work!

Answer 1

You can create a Viewbag with the information of Type:

  public ActionResult Editar(int id)
    {
        //Pesquisar projeto selecionado
        ProjetoDAO proj_dao = new ProjetoDAO();
        Projeto proj = proj_dao.listById(id);

        //Pesquisar todos os TIPOS de projetos
        ProjetoTipoDAO proj_tipo_dao = new ProjetoTipoDAO();
        List<ProjetoTipo> lista_projetotipo = proj_tipo_dao.ListAll();

        SelectList dropDown = new SelectList(lista_projetotipo, "ProjTipoId", "ProjTipoNome");

        ViewBag.ListaTiposProjeto = dropDown;

        return View(proj);
    }

View:

 <div class="row">
                <div class="form-group">
                    <div class="col-md-2">
                        @Html.LabelFor(model => model.ProjTipo, new { @class = "control-label" })
                    </div>
                    <div class="col-md-10">
                        @Html.DropDownListFor(model => model.ProjTipo, (SelectList)ViewBag.ListaTiposProjeto, "Selecione um item", new { @class = "form-control" })
                    </div>
                </div>
            </div>

It is necessary that in your Project class you have the Project Type ID and that in the recovery of the object this ID has value

Answer 2

In your viewmodel, create the following attribute:

public SelectList TiposProjeto { get; set; }

there, where you prepare your screen (controller or some other layer), you popularize:

model.TiposProjeto = new SelectList(proj_tipo_dao.ListAll(), "ProjTipoId", "ProjTipoNome");

in your cshtml file:

@Html.DropDownListFor(model => model.ProjTipoId, Model.TiposProjeto, "Selecione...", new { @class = "form-control" })

this way, if it already has value within ProjTipoId, he will already come selected.