Many-to-many relationship with Asp.net MVC and Entity Framework

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Many-to-many relationship with Asp.net MVC and Entity Framework

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#1 by (5 votes)

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I'm creating a project to study Asp.net MVC 5 along with Entity Framework 6 , and I came across a big question in a many-to-many relationship . I used model generated from the database, and I created the controllers and views automatically by Visual Studio .

In my database I have the many-to-many relationship between the User table and Projects table, which results in the Project_Path table as follows the image below:

Thistable,asitsnamesays,isdesignedtostoreuserdatathatwillbepartofsomeproject,orseveral.

WhencreatingmyedmxinmyVisualStudioproject,theTeam_Projecttableisnotcreatedinthemodelsclasses,andonlytherelationshipgoesinedmx,asintheimagebelow:

So I'm faced with the question of how I'm going to populate my Project_Table table? I'm a little lost here on how I will relate my users to the projects, using ASP.NET MVC?

In the project's Create method code I have the following code, and in this there is nothing that relates to the Project_Profile table:

// GET: Projeto/Create
public ActionResult Create()
{
    ViewBag.prioridade = new SelectList(db.prioridade, "prioridade1", "prioridade1");
    ViewBag.status = new SelectList(db.status, "status1", "status1");
    ViewBag.responsavel = new SelectList(db.usuario, "id", "nome");
    return View();
}

// POST: Projeto/Create
// 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 Create([Bind(Include = "id,nome,descricao,data_inicio,responsavel,prioridade,status")] projeto projeto)
{
    if (ModelState.IsValid)
    {
        db.projeto.Add(projeto);
        db.SaveChanges();
        return RedirectToAction("Index");
    }

    ViewBag.prioridade = new SelectList(db.prioridade, "prioridade1", "prioridade1", projeto.prioridade);
    ViewBag.status = new SelectList(db.status, "status1", "status1", projeto.status);
    ViewBag.responsavel = new SelectList(db.usuario, "id", "nome", projeto.responsavel);
    return View(projeto);
}

The big question is this, how to work with the many-to-many relationship, so that I can insert data into more than one table at a time, in my case in the Project table, strong> Project_Professor , thus defining the users who are part of the project.

Note: I have a great experience already with projects in WebForms, however I am now going behind the learning in asp.net mvc, entity framework and webapi.

asp.net-mvc-5

asked by anonymous 13.09.2014 / 01:32

1 answer

R: to which objects does the names () attribute apply? Is it possible to limit the amount of rows of a class attribute that is a list via JPQL?

score 5 · Accepted Answer

The creation of tables by EDMX causes the Entity Framework to configure this associative table by Fluent API , within its context file (a class that derives DbContext ). From experience, I do not recommend using this way for three reasons:

It's not clear how and when the Entity Framework will make the association for you;
The association can not be extended, receive more properties, rules, etc.
Your example already shows that there is no Scaffolding (automatic prototyping) of the association, and it has to be done manually.

Ideally, you should create the Model Equipe_Projeto manually, associating Projeto and Equipe with 1 to N. This avoids confusion.

In addition, I do not recommend you continue to spend too much time in this approach with the EDMX file. Using Attributes , this approach quickly becomes obsolete.