Marking a Field as Required

Question

If I have a dbml file that contains say a Customer class with say a single property of CompanyName;

public partial class Customer : INotifyPropertyChanging, INotifyPropertyChanged
private string _CompanyName;
public string CompanyName
{
  get

Now, given that the above is in a dbml and thus generated I obviously should avoid editing it like the plague.

So I have created another class like so;

public partial class Customer
{
    [Required]
    public string CompanyName{get;set;}
}

The reason for this is because I want to decorate my field as being required.

However this doesn't work as I get the compile error "...already contains a definition for 'CustomerID'".

Does anyone know a way around this or is there a better way to mark fields as required or of validating a model?

Answer 1

The solution is to use a MetadataType attribute with an additional class that contains the data validation annotations.

See: http://weblogs.asp.net/scottgu/archive/2010/01/15/asp-net-mvc-2-model-validation.aspx

Answer 2

Or you could use ViewModel pattern. This also gives you flexibility is binding your model to the view when you want to use things like dropdowns. We use it with AutoMapper.