Question

Quick question on best practices.

I have one project MVC3 + razor that on my class, on each of my properties, I have some validations like these:

    [StringLength(20)]
    [RegularExpression(@"^[1-9][0-9]*$",ErrorMessage="Only Numbers Allowed") ]
    [Required(AllowEmptyStrings = false, ErrorMessage = "Please Inform The Code")]
    [Display(Name = "Code")]
    public string gCode { get; set; }

This is on my, let’s say, Customer class on my model. Validation works perfectly on the UI.

On a second project, when using Entity Framework – database first, I have my edmx file with my entities and I query the database using ObjectContext, which means the Customer class is built by EF.

Where am I supposed to add these validations now?

Answer 1

Model first has this problem – but it can be solved using MetaData. Say you have a generated entity called Field and the Value field you want to decorate with a [Required] attribute, just do the following:

namespace Model.Entities {

    [MetadataType(typeof(FieldMetadata))]
    public partial class Field : EntityBase {

    }

    class FieldMetadata {
        [Required]
        public object Value;
    }
}

Here you are adding metadata to the Value member of an existing class’s members that you cannot modify.

EDIT: If it doesn’t work, make a call to the TypeDescriptor as well.

TypeDescriptor.AddProvider(new AssociatedMetadataTypeTypeDescriptionProvider(typeof(Field), typeof(FieldMetadata)), typeof(Field));