How to add data annotation for entities automatically created by Data-First?

Question

If model-first, we use [MetadataType(typeof(ConceptMetadataSource))] to attach a MetadataSource file which contains all the data annotations like [Hidden

Answer 1

All you have to do is create another partial class and use metadatatype attribute. Here is the sample code

//This is generated by EDMX

namespace DataLayer
{
    using System;
    using System.Collections.Generic;

    public partial class Customer
    {
        public Customer()
        {
            this.CustomerAddresses = new HashSet();
            this.CustomerOrders = new HashSet();
        }

        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string EmailId { get; set; }


        public Nullable DateOfBirth { get; set; }

        public virtual ICollection CustomerAddresses { get; set; }
        public virtual ICollection CustomerOrders { get; set; }
    }
}

Add following code manually

namespace DataLayer
{
    [MetadataType(typeof(CustomerMetaData))]
    public partial  class Customer
    {

    }
    public class CustomerMetaData
    {
        [StringLength(10, ErrorMessage = "First name must be 25 characters or less in length.")]
        [Required(ErrorMessage = "First name is required.")]
        public String FirstName { get; set; }
    }
}