Edit MVC with Foreign Key

Question

I need to upgrade my editLivros, Next I’ll explain my project.

Autores
-------
IdAutor
Nome

Livros
--------
IdLivro
Nome
IdAutor

I am registering the Authors and Books correctly, when I am registering the Livro, I make a ViewBag for the list of authors :

LivrosController to catch the Authors:

ViewBag.IdAutor = new SelectList(db.Autores, "IdAutor", "Nome");

DropDown of the Authors in View Create Books:

@Html.DropDownList("IdAutor", ViewBag.IdAutor as SelectList, new { @class = "form-control" })

Model Books

    public partial class Livros
{
    [Key]
    public int IdLivro { get; set; }

    [Required]
    [StringLength(50)]
    public string Nome { get; set; }

    public int IdAutor { get; set; }

    public virtual Autores Autores { get; set; }

}

Model authors

    public partial class Autores
{
    [Key]
    public int IdAutor { get; set; }

    [StringLength(50)]
    public string Nome { get; set; }
}

Problem:

My problem, is when I edit the book, automatically the Visual Studio picks up the Nome of the book and the IdAutor of the book, however, needed to generate a dropbox with the authors, yes edit the author of the book, passing the model Idautor Autores

Thank you.

Answer 1

Well, just keep doing as you are. Sending the ViewBag with the SelectList for View Create Books, but in this case you will already send a selected value.

By creating a SelectList, it is possible to set as parameter the item to be selected (details). So when you arrive at your View, your DropDownList will present all available items, but will leave marked the indicated item.

Your code would look like this:

ViewBag.IdAutor = new SelectList(db.Autores, "IdAutor", "Nome", Livro.IdAutor);

There is also the possibility of doing as in reply that @Randrade posted in the comments, what changes is only the context.

Answer 2

No Edit do LivrosController:

ViewBag.listaAutores = db.Autores;

Na View do Livros:

@Html.DropDownListFor(model => model.IdAutor, ((IEnumerable<MVCCodeFirst.Models.Autores>)ViewBag.listaAutores).Select(option => new SelectListItem
{
    Text = option.Nome,
    Value = option.IdAutor.ToString(),
    Selected = (Model != null) && (Model.IdAutor == option.IdAutor)
}), "Selecione...", new { @class = "form-control" })