MVC 4 Manual validation with Data Annotation - entity-framework

Question

I admit I found many similar question but not exactly this :)
I have entities with data annotation attributes:
public class BaseEntity
{
[Required, DataType(DataType.DateTime)]
public DateTime CreatedAt { get; set; }
public string CreatedBy { get; set; }
}
public class ExchangeRights : BaseEntity
{
[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
[Required, DataType(DataType.EmailAddress)]
public string Email { get; set; }
}
And I try to validate an empty object:
ExchangeRights r = new ExchangeRights();
ValidationContext vCtx = new ValidationContext(r);
List<ValidationResult> res = new List<ValidationResult>();
Validator.TryValidateObject(r, vCtx, res, true);
It's only result one Error. That the Email field is required. But not indicate that there is not email format and not indicate that the CreatedAt field is not set (ok maybe it's because non nullable value type)
But here is the twist.
First I really want that every error should be indicated it's empty, it's not email format.
But the bigger problem is that if I set the Email to "asd" the method return no error.
However it's wierd if I use this Entity with strongly typed view (using MVC4 with Razor) on a create page all works fine.
The form indicate that the Email is requires or if I set than it says not valid email address format.
Also indicates that the CreatedAt field is required (with or without the Required attribute!!) and if I set it it says not valid datetime format.
Any help/idea/hunch would be appreciated.
Thanks,
Péter

Answer 1

for the validation of the email you should use the EmailAddress validation attribute. [EmailAddress].
For the CreatedAt, as DateTime is a non nullable type, when you create a ExchangeRights instance, the property CreatedAt is populated with DateTime.MinValue. So the property has a value. If you want a differente behavior, use DateTime? instead of DateTime.
Hope this helps.

Answer 2

You can use the DataTypeAttribute attribute for the following reasons: to provide additional type information for a data field, to associate a custom field template with a data field. DataTypeAttribute doesn't used for validation it's can be used for provide some additional metadata information. To validate email you can use DataAnnotations Extensions EmailAttribute or write you own validation attribute.
You can find more information in
http://msdn.microsoft.com/en-us/library/system.componentmodel.dataannotations.datatypeattribute.aspx