Meta Data - Annotating Models

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One of the issues with using Entity Framework is that you may want some special annotation but you don't want to use a DTO or other object outside of EF.

One way to afford you the opportunity to Annotate on the original EF model is to extend with a partial class of meta data.

In your Data Models folder (or really anywhere in your data project) you would add a class (Partial Classes) that would contain empty pointers to your data classes - (in my tt files I have a company class and a systemUser class which represent models from the tables in my database):
PartialClasses.cs

using System.ComponentModel.DataAnnotations;

namespace MySite.Data
{

    [MetadataType(typeof(systemUsersMetadata))]
    public partial class systemUser
    {
    }
    [MetadataType(typeof(companyMetadata))]
    public partial class company
    {
    }
}

Once you have this setup you can begin to annotate! Create a systemUsersMetadata.cs class and you can now add annotations while still using your original EF model - and you don't have to annotate everything  - just the fields you want.

public class systemUsersMetadata
    {
        [RegularExpression(@"^[^<>*]+$", ErrorMessage = "Special characters are not allowed")]
        [Required(ErrorMessage = "First Name is required")]
        [MaxLength(30, ErrorMessage = "First Name may not exceed 30 characters")]
        [Display(Name = "First Name")]
        public string firstName { get; set; }

         [RegularExpression(@"^[^<>*]+$", ErrorMessage = "Special characters are not allowed")]
        [Display(Name = "Last Name")]
        [Required(ErrorMessage = "Last Name is required")]
        [MaxLength(30, ErrorMessage = "Last Name may not exceed 30 characters")]
        public string lastName { get; set; }

         [Display(Name = "Middle Name")]
        public string middleName { get; set; }
        [Display(Name = "Email")]
        [DataType(DataType.EmailAddress)]
        [Required(ErrorMessage = "Email is required")]
        [MaxLength(60, ErrorMessage = "Email Address may not exceed 60 characters")]
        public string email { get; set; }

         [Display(Name = "Phone")]
        [RegularExpression(@"^[^<>*]+$", ErrorMessage = "Special characters are not allowed")]
        [Required(ErrorMessage ="Phone is required.")]
        [MaxLength(15, ErrorMessage = "Phone number may not exceed 15 characters")]
        public string phone { get; set; }
}

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