How to resolve error: The best overloaded method match for

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How to resolve error: The best overloaded method match for

Asked 8 years, 10 months ago

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Following the models of that question, when I pass the commands to write the form data to the database, before even copying Visual Studio, points out the following error:

"The best overloaded method match for [...] has some invalid Arguments"

Follow the examples of the controller (remembering that the view and viewmodel are in the linked question at the beginning)

Controller

public ActionResult Novo()
    {
        ViewBag.Nacionalidade = new SelectList(db.Util.Where(u => u.tipo == 14), "id", "nome");

        var candidato = new CandidatoViewModel();

        return View(candidato);
    }

    [HttpPost]
    public ActionResult Novo(CandidatoViewModel candidato)
    {
        if (ModelState.IsValid) 
        {         
            db.Candidato.Add(candidato); // erro esta aqui

            db.SaveChanges();
            return RedirectToAction("VerCandidato", new { id = candidato.id });            
        }

        ViewBag.Nacionalidade = new SelectList(db.Util.Where(u => u.tipo == 14), "id", "nome", candidato.id_nacionalidade);

        return View(candidato);
    }

On which line does this error occur?

– Leonel Sanches da Silva

2015/11/17 at 16:24
The error in question occurs when you pass invalid parameters when calling a method for example.

– Pedro Camara Junior

2015/11/17 at 16:24
Ta ali no codigo Cigano, commented "db.Candidato.Add(candidate)/error esta aqui"

– Matheus Silva

2015/11/17 at 16:25
@Pedrocamarajunior But my Viewmodel and Model have exactly the same properties, except for the list I used in viewModel and the model has no... I still don’t understand very well how this mapping is done when you have multiple models, if you have articles/Docs for reference and studies would be of great help, without being those of codeproject...

– Matheus Silva

2015/11/17 at 16:30

1 answer

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by Leonel Sanches da Silva • **88,623** points · Answer 1 · 2015-11-17T16:32:47+00:00

Well, it won’t work, obviously. You’re trying to add CandidatoViewModel in context, but a Viewmodel is not mapped by context by definition.

The right thing would be for you to do:

[HttpPost]
public ActionResult Novo(CandidatoViewModel candidato)
{
    if (ModelState.IsValid) 
    {         
        Candidato candidatoModel = candidato;
        db.Candidato.Add(candidatoModel); 

        db.SaveChanges();
        return RedirectToAction("VerCandidato", new { id = candidato.id });            
    }

    ViewBag.Nacionalidade = new SelectList(db.Util.Where(u => u.tipo == 14), "id", "nome", candidato.id_nacionalidade);

    return View(candidato);
}

This:

Candidato candidatoModel = candidato;

It’s worth it if you implement an implicit operator, as follows:

public class Candidato
{
    // Aqui vão as declarações normais do Model

    public static implicit operator Candidato(CandidatoViewModel c)
    {
        return new Candidato {
            Nome = c.Nome,
            Idade = c.Idade,
            ...
        };
    }
}

There are still those who use Automapper instead of using an implicit operator, but opinionated speaking, I’m not a fan.