ASP.NET MVC Required DataAnnotation

Question

I am building my first app with ASP.NET, and I am using Entity Framework.

I have two classes:

public class Owner
{
    public int ID { get; set; }
    [Required(ErrorMessage="Empty Owner name")]
    [MaxLength(10,ErrorMessage="Up to 10 chars")]
    [Display(Name="Owners name")]
    public string Name { get; set; }
    public DateTime Born { get; set; }
    public virtual List<Dog> dogs { get; set; }
}
public class Dog
{
    public int ID { get; set; }
    [Required(ErrorMessage="Empty dog name")]
    [MaxLength(10,ErrorMessage="Up to 10 chars")]
    [Display(Name="Dogs name")]
    public string Name { get; set; }
    public virtual Owner owner { get; set; }
}

I can add owners to the database, but I cannot add dogs. I am using a textbox and a listbox in the View like:

@using (Html.BeginForm("New", "Dog"))
{
    @Html.LabelFor(x => x.Name);
    @Html.TextBoxFor(x => x.Name);
    <br />
    @Html.ListBoxFor(x => x.owner.ID, new MvcApplication2.Models.GazdiKutyaDB().GetOwners());
    <br />
    <input type="submit" />
}

I created a GetOwners method to add the existing owners to a listbox, and for the user, to select who is the owner of the dog.

public List<SelectListItem> GetOwners()
{
    List<SelectListItem> g = new List<SelectListItem>();
    foreach (Owner item in owners)
    {
         SelectListItem sli = new SelectListItem();
         sli.Text = item.Name;
         sli.Value = item.ID.ToString();
         g.Add(sli);
    }
    return g;
}

I created a Controller for the Dogs. Here is my adding method:

[HttpGet]
public ActionResult New()
{            
     return View();
}
[HttpPost]
public ActionResult New(Dog k)
{
     if (ModelState.IsValid)
     {
          k.owner = (from x in db.owners
                      where x.ID == k.owner.ID
                      select x).FirstOrDefault();
          db.dogs.Add(k);
          db.SaveChanges();
          return RedirectToAction("Index", "Dog"); 
     }
     else
     {
          return View(k);
     }
}

I inserted breakpoints, and the reason why ModelState.IsValid is false, is that the owners name is empty: [Required(ErrorMessage="Empty Owner name")] I don't understand this, because I want to add a dog there.

jamcoupe · Accepted Answer · 2013-05-06 16:05:00Z

2

Why not add the ownerID to the class like so:

public class Dog
{
    public int ID { get; set; }
    [Required(ErrorMessage="Empty dog name")]
    [MaxLength(10,ErrorMessage="Up to 10 chars")]
    [Display(Name="Dogs name")]
    public string Name { get; set; }
    public int ownerID { get; set; }
}

This is the easiest way to do it (in my opinion) when you are working with a database.

Here is an excellent video tutorial, showing ways to get your models to work as expected in EF

edited May 6, 2013 at 16:05

answered May 6, 2013 at 15:59

jamcoupe

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