Map Id of one model to another without a Dropdownlist

Question

I had a problem making relationships in my application. my project is from a school, and in it I have to have the occurrences. But when it comes to relating the Student to the Occurrence happened to me that, in the view create of the occurrences, I see a dropdownlist with the registered students, so that I do the relationship, ie, Mask the occurrence in the student, I mean, what the student did. What I really wanted was that when I uploaded the student details, I would have a Collapse(accordion type) where the user could put the occurrence for that specific student, taking his ID, ie, passing the student id in the detail view and the same student id for the accurate mapping of the occurrence. That is, register the occurrence for that student, and that it is not loaded a dropdaownlist with the students.

I’ll put here, the student registration view to see what can be done:

     @using (Html.BeginForm()) 
     {
     @Html.AntiForgeryToken()

    <div class="form-horizontal">
    <h4>Ocorrencia</h4>
    <hr />
    @Html.ValidationSummary(true)

    <div class="form-group">
        @Html.LabelFor(model => model.Tipo, new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Tipo)
            @Html.ValidationMessageFor(model => model.Tipo)
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Causa, new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Causa)
            @Html.ValidationMessageFor(model => model.Causa)
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Observacao, new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Observacao)
            @Html.ValidationMessageFor(model => model.Observacao)
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.AlunoId, "AlunoId", new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownList("AlunoId", String.Empty)
            @Html.ValidationMessageFor(model => model.AlunoId)
        </div>
    </div>

    <div class="form-group">
        <div class="col-md-offset-2 col-md-10">
            <input type="submit" value="Salvar" class="btn btn-default" />
        </div>
    </div>
</div>
}

Here’s the part of the controller that populates the dropdownlist:

     public ActionResult Index()
    {
        var ocorrencias = db.Ocorrencias.Include(o => o.Aluno);
        return View(ocorrencias.ToList());
    }

    // GET: /Ocorrencias/Detalhes/5
    public ActionResult Detalhes(long? id)
    {
        if (id == null)
        {
            return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
        }
        Ocorrencia ocorrencia = db.Ocorrencias.Find(id);
        if (ocorrencia == null)
        {
            return HttpNotFound();
        }
        return View(ocorrencia);
    }

    // GET: /Ocorrencias/Adiciona
    public ActionResult Adiciona()
    {
        ViewBag.AlunoId = new SelectList(db.Alunos, "Id", "Nome");
        return View();
    }

    // POST: /Ocorrencias/Adiciona
    // To protect from overposting attacks, please enable the specific properties you            want to bind to, for 
    // more details see http://go.microsoft.com/fwlink/?LinkId=317598.
    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Adiciona([Bind(Include="Id,Tipo,Causa,Observacao,AlunoId")]    Ocorrencia ocorrencia)
    {
        if (ModelState.IsValid)
        {
            db.Ocorrencias.Add(ocorrencia);
            db.SaveChanges();
            return RedirectToAction("Index");
        }

        ViewBag.AlunoId = new SelectList(db.Alunos, "Id", "Nome", ocorrencia.AlunoId);
        return View(ocorrencia);
    }

    // GET: /Ocorrencias/Edita/5
    public ActionResult Edita(long? id)
    {
        if (id == null)
        {
            return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
        }
        Ocorrencia ocorrencia = db.Ocorrencias.Find(id);
        if (ocorrencia == null)
        {
            return HttpNotFound();
        }
        ViewBag.AlunoId = new SelectList(db.Alunos, "Id", "Nome", ocorrencia.AlunoId);
        return View(ocorrencia);
    }

    // POST: /Ocorrencias/Edita/5
    // To protect from overposting attacks, please enable the specific properties you want to bind to, for 
    // more details see http://go.microsoft.com/fwlink/?LinkId=317598.
    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Edita([Bind(Include="Id,Tipo,Causa,Observacao,AlunoId")] Ocorrencia ocorrencia)
    {
        if (ModelState.IsValid)
        {
            db.Entry(ocorrencia).State = EntityState.Modified;
            db.SaveChanges();
            return RedirectToAction("Index");
        }
        ViewBag.AlunoId = new SelectList(db.Alunos, "Id", "Nome", ocorrencia.AlunoId);
        return View(ocorrencia);
    }

    // GET: /Ocorrencias/Remove/5
    public ActionResult Remove(long? id)
    {
        if (id == null)
        {
            return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
        }
        Ocorrencia ocorrencia = db.Ocorrencias.Find(id);
        if (ocorrencia == null)
        {
            return HttpNotFound();
        }
        return View(ocorrencia);
    }

    // POST: /Ocorrencias/Remove/5
    [HttpPost, ActionName("Remove")]
    [ValidateAntiForgeryToken]
    public ActionResult DeleteConfirmed(long id)
    {
        Ocorrencia ocorrencia = db.Ocorrencias.Find(id);
        db.Ocorrencias.Remove(ocorrencia);
        db.SaveChanges();
        return RedirectToAction("Index");
    }

And here’s what I put on the Students model, which makes the load of students' names appear on the dropdownlist:

    public ICollection<Ocorrencia> Ocorrencias { get; set; }
    public Aluno()
    {
        this.Ocorrencias = new HashSet<Ocorrencia>();
    }

Answer 1

Just change:

@Html.DropDownList("AlunoId", String.Empty)

For:

@Html.HiddenFor(model => model.AlunoId)
<div>@model.Aluno.Nome</div>

Controller

public ActionResult AdicionarOcorrencia(int id)
{
    var aluno = db.Alunos.SingleOrDefault(a => a.Id == id);
    return View(aluno);
}