Question

I have model that looks like this:

public class Lesson
{
    public int Id { get; set; }

    [Required(ErrorMessage = "Naam voor de les is verplicht")]
    [Display(Name="Naam")]
    public string Name { get; set; }

    [Required(ErrorMessage = "Tijd is verplicht")]
    [Display(Name="Tijd")]
    public string Time { get; set; }

    //Prijs is default exclusief BTW
    [Required(ErrorMessage = "Prijs is verplicht")]
    [Display(Name="Prijs (excl btw)")]
    public double Price { get; set; }

    [Display(Name = "Maximum aantal leerlingen")]
    public int MaxStudents { get; set; }
}

And a create view that looks like this:

<div>
    <div>
        @Html.LabelFor(model => model.Name)
    </div>
    <div>
        @Html.TextBoxFor(model => model.Name, new { @class = "gt-form-text" })
        @Html.ValidationMessageFor(model => model.Name)
    </div>
    <div>
        @Html.LabelFor(model => model.Time)
    </div>
    <div>
        @Html.TextBoxFor(model => model.Time, new { @class = "gt-form-text" })
        @Html.ValidationMessageFor(model => model.Time)
    </div>
    <div>
        @Html.LabelFor(model => model.Price)
    </div>
    <div>
        @Html.TextBoxFor(model => model.Price, new { @class = "gt-form-text" })
        @Html.ValidationMessageFor(model => model.Price)
     </div>
     <div>
         @Html.LabelFor(model => model.MaxStudents)
     </div>
     <div>
         @Html.TextBoxFor(model => model.MaxStudents, 
             new { @class = "gt-form-text" })
         @Html.ValidationMessageFor(model => model.MaxStudents)
     </div>
 </div>

In the Application_Start() method I set DataAnnotationsModelValidatorProvider.AddImplicitRequiredAttributeForValueTypes to false.

MaxStudents is nullable and not required, nevertheless, if MaxStudents is null, the Modelstate is not valid (ModelState.IsValid = false).

My errormessage is not shown, instead of that I get the errormessage is A value is required.

What can I do to get ModelState.IsValid to be true?

Answer 1

Someone shared this with me, and I’ll pass it on in case it helps. Sometimes those validation errors get swallowed up and are hard to find. When I was having a similar issue, I added this code to my ActionResult (HttpPost) and it got me right to the error in question.

            try
        {
            db.Entry(myModel).State = EntityState.Modified;
            db.SaveChanges();

        }
        catch (DbEntityValidationException dbEx)
        {
            foreach (var validationErrors in dbEx.EntityValidationErrors)
            {
                foreach (var validationError in validationErrors.ValidationErrors)
                {
                    Trace.TraceInformation("Property: {0} Error: {1}", validationError.PropertyName, validationError.ErrorMessage);
                }
            }
        }           // }