Custom IModelBinder and Database Access

For a user object in my asp.net mvc project, I have written a custom modelbinder to check whether passwords are valid and whether two matching passwords were entered etc..

The login name needs to be unique though, I was wondering whether I can check for that in the modelbinder, or is this considered bad practise ?

The thing is that the binder is called before you even get to the controller, so I would have two instances of my dataContext floating around and thus multiple connections to the database, I guess I could set up a factory of sorts for that.

This is a code snippet of what I do now in the controller:

// POST: /Users/Create
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Create(Users user)
{            
    myDataContext db = new myDataContext();

    if (!ViewData.ModelState.IsValid)
    {                
        return View(user);
    }            

    Users testUser = db.Users.SingleOrDefault(p => p.LoginNaam == user.LoginNaam);
    if (testUser != null) { //Error stuff here }
}

From stackoverflow

• I would not check the username availability in the model binder. I think it's the CreateUser method's job to do that in this case.

  So the action would be like this :

  // POST: /Users/Create
  [AcceptVerbs(HttpVerbs.Post)]
  public ActionResult Create(Users user)
  {            
      myDataContext db = new myDataContext();
  
      if (!ViewData.ModelState.IsValid)
      {                
          return View(user);
      }
  
      try {
          db.CreateUser(User);
      }
      catch (ArgumentException e) {
          ModelState.AddModelError(e.ParamName, e.Message);
          return View(user);
      }
      return View("UserCreated", user)
  }
  

  Morph : This is similar to what I was doing so I guess that's the right way to go !