Problem with Entity Framework Relationship

Question

I am having problems in the relationship of my bank, I am developing an application that manages Courses, I am still beginner in Asp.net MVC. I have two tables Pupil and Course, and I have another table that makes the association between these two tables Hallucinogenic.

Model Aluno

 public class Aluno
{
    [Key]
    public int Id { get; set; }

    public string Nome { get; set; }

    ...

    public virtual ICollection<AlunoCurso> AlunoCursos { get; set; } }

Model Curso

public class Curso
{
    [Key]
    public int Id { get; set; }

    public string Nome_Curso { get; set; }

    ...

    public virtual Aluno Aluno { get; set; }

    public ICollection<AlunoCurso> AlunoCursos { get; set; } }

Model Alunocurso

public class AlunoCurso
{
    [Key]
    public int Id { get; set; }

    public int AlunoId { get; set; }

    public int CursoId { get; set; }

    public bool Aprovado { get; set; }

    public virtual Aluno Aluno { get; set; }

    public virtual Curso Curso { get; set; }

}

The problem is that the column Alunoid on the table of Course is not receiving the Id student’s.

But in the association table Hallucinogenic is receiving the value of the field Alunoid.

List of Student Courses

public ActionResult MeusCursos()
    {
        Aluno aluno = db.Alunos.FirstOrDefault(a => a.Usuario == User.Identity.Name);
        if (aluno != null)
            return View("MeusCursos", db.Cursos.ToList());

        return View();}

View Meuscursos

@model IEnumerable<MeuProjeto.Models.Curso>

@{
    Layout = "/Views/Shared/_Layout.cshtml";
}

<h2>Meus Cursos</h2>

<table class="table table-hover">
    <tr>
        <th>
            Curso
        </th>
        <th>
            Aluno
        </th>
        <th>
            Aprovado?
        </th>

        <th></th>
    </tr>

    @foreach (var item in Model)
    {
        <tr>
            <td>
                @Html.DisplayFor(modelItem => item.Nome_Curso)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.AlunoCursos)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.Aprovado)
            </td>
            <td>
                <div class="btn-group">
                    <div class="col-md-offset-2 col-md-10">
                        @if (item.Aprovado == false)
                        {
                            <input type="submit" value="Pendente de Aprovação" name="meusCursos" class="cursos btn btn-success" disabled="disabled" data-id="@item.Id"/>
                        }
                        else
                        {
                            <input type="submit" value="Emitir Declaração" name="meusCursos" class="cursos btn btn-default" enable="enable" />
                        }
                    </div>
                </div>
            </td>
        </tr>
    }

</table>

Listing Screen

Answer 1

This isn’t exactly a problem. It’s just a code scrawl that’s been left behind and hasn’t been removed.

See here:

public class Curso
{
    [Key]
    public int Id { get; set; }

    public string Nome_Curso { get; set; }

    ...


    public virtual Aluno Aluno { get; set; } // Este pode ser retirado

    public ICollection<AlunoCurso> AlunoCursos { get; set; } 
}

As now a student can be enrolled in several courses, and a course can have several students, this association:

public virtual Aluno Aluno { get; set; }

It has lost the sense of being there, and can be removed.

After removing, do not forget to generate a new Migration for the removal of the column properly.

---

EDIT

To Action is incorrect. If you want to read a student’s courses, simply select only the student and use the navigation properties:

public ActionResult MeusCursos()
{
    var aluno = db.Alunos.FirstOrDefault(a => a.Usuario == User.Identity.Name);
    if (aluno != null)
        return View("MeusCursos", aluno);

    return View();
}

Notice that I changed @model of View:

@model IEnumerable<MeuProjeto.Models.Aluno>

@{
    Layout = "/Views/Shared/_Layout.cshtml";
}

<h2>Meus Cursos</h2>

<table class="table table-hover">
    <tr>
        <th>
            Curso
        </th>
        <th>
            Aprovado?
        </th>

        <th></th>
    </tr>

    @foreach (var item in Model.AlunoCursos)
    {
        <tr>
            <td>
                @Html.DisplayFor(modelItem => item.Curso.Nome_Curso)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.Aprovado)
            </td>
            <td>
                <div class="btn-group">
                    <div class="col-md-offset-2 col-md-10">
                        @if (item.Aprovado == false)
                        {
                            <input type="submit" value="Pendente de Aprovação" name="meusCursos" class="cursos btn btn-success" disabled="disabled" data-id="@item.Id"/>
                        }
                        else
                        {
                            <input type="submit" value="Emitir Declaração" name="meusCursos" class="cursos btn btn-default" enable="enable" />
                        }
                    </div>
                </div>
            </td>
        </tr>
    }

</table>