ASP.NET MVC - model validation of type int and DateTime

Question

Let's have a model

     public class Model 
     {
         public int Number { get; set; }
         public DateTime Date { get; set; } 
     }

I observed following behavior. Number property has value 0 and Date has 1.1 0001 00:00:00 when nothing is submitted an the value of ModelState.IsValid is true.

The DataAnnotationsModelValidatorProvider class and GetValidators method has this pieco of code

        // Add an implied [Required] attribute for any non-nullable value type,
        // unless they've configured us not to do that. 
        if (AddImplicitRequiredAttributeForValueTypes &&
                metadata.IsRequired && 
                !attributes.Any(a => a is RequiredAttribute)) { 
            attributes = attributes.Concat(new[] { new RequiredAttribute() });
        }

If I understand this right then the Number property and DateTime property should get set a RequiredAttribute and validation routine should set the model invalid and generate appropriate error messages.

So my question is why ins't the model invalid ?

I'm using ASP.NET MVC 3

Darin Dimitrov · Accepted Answer · 2012-01-19 10:26:31Z

5

So my question is why ins't the model invalid ?

Because 0 is a perfectly valid integer and 1.1 0001 00:00:00 is a perfectly valid DateTime. I don't see why would you expect your model to be invalid.

Make em nullable and decorate with the Required attribute to achieve the desired effect:

public class Model 
{
     [Required]
     public int? Number { get; set; }

     [Required]
     public DateTime? Date { get; set; } 
}

answered Jan 19, 2012 at 10:26

Darin Dimitrov

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6 Comments

user49126 Over a year ago

The model should be invalid becauce no value was send from the form. These values didn't come from a input. So the required rule was broken. Using a nullable type for a required value seem to me wrong. In first place a non nullable int should behave like it is required without any required attribute. And nullable int should behave like a non required value

Darin Dimitrov Over a year ago

@user49126, you cannot store no value in a non-nullable type such as int or DateTime. The CLR won't allow you to no matter how hard you try. The way it works is that the default model binder instantiates the model (and of course all its properties are assigned to their default values, which in your case with value types will be their respective defaults) and then calls the validation. Since the 2 properties have perfectly valid values inside them there is no validation error and it makes perfect sense.

user49126 Over a year ago

I know,but at least the model should be invalid.

Darin Dimitrov Over a year ago

@user49126, why do you think so? It doesn't make sense. The model contains valid values for its properties, so the model is perfectly valid.

user49126 Over a year ago

But this value wasn't provided by the form. It's a C# implementation concern. Imho it should works like NotEmpty validator in FluentValidation lib. fluentvalidation.codeplex.com/…

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