Data Annotations with Entity Framework 5.0 (database first)

Question

What is the best way to use data annotations for validation if I'm using an Entity Framework (v5.0) database first approach?

This is my partial class created by Entity Framework:

//------------------------------------------------------------------------------ // <auto-generated> //    This code was generated from a template. // //    Manual changes to this file may cause unexpected behavior in your application. //    Manual changes to this file will be overwritten if the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------  using System.ComponentModel.DataAnnotations;  namespace ACore {     using System;     using System.Collections.Generic;      public partial class PayrollMarkup_State     {         [UIHint("StatesEditor")] // <-- I added this line but it will be overwritten         public string State { get; set; }         public Nullable<float> MaintenancePercentage { get; set; }         public Nullable<float> OfficePercentage { get; set; }     } } 

I tried this with no success....

Entity Framework generated file: 'PayrollMarkup_State.cs'

//------------------------------------------------------------------------------ // <auto-generated> //    This code was generated from a template. // //    Manual changes to this file may cause unexpected behavior in your application. //    Manual changes to this file will be overwritten if the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------  using System.ComponentModel.DataAnnotations;  namespace ACore {     using System;     using System.Collections.Generic;      public partial class PayrollMarkup_State     {         public string State { get; set; }         public Nullable<float> MaintenancePercentage { get; set; }         public Nullable<float> OfficePercentage { get; set; }     } } 

I then created this file in a different directory: 'PayrollMarkup_state.cs'

using System; using System.Collections.Generic; using System.ComponentModel.DataAnnotations; using System.Linq; using System.Web;  namespace ACore.Models {     [MetadataType(typeof(PayrollMarkupMetadata))]     public partial class PayrollMarkup_State     {     }      public class PayrollMarkupMetadata     {         [UIHint("StatesEditor")]         public string State; // Has to have the same type and name as your model     } } 

Answer 1

Although it's somewhat painful, you need to create a class to use as the MetadataType for your model class.

[MetadataType(typeof(PayrollMarkupMetadata)) public partial class PayrollMarkup_State {   ... }  public class PayrollMarkupMetadata {     [UIHint("StatesEditor")]     public string State; // Has to have the same type and name as your model     // etc. } 

Answer 2

You have a namespace problem - you have defined two different PayrollMarkup_State classes, one under the ACore namespace and one under the ACore.Models namespace. Change the namespace to ACore (from ACore.Models) in the file containing the metadata type definition.