How to preserve dataannotation in MVC data first approach

Question

I am using MVC database first approach and created one .edmx file.

Now my all the tables are available in this model.tt file. I have also defined some dataannotation on those fields of table.

But What I have noticed that when ever I tried to update this model then value of dataanotation will be lapse.

Any thoughts please.

Answer 1

Yes it's kinda funny how much you read about annotations but you can't actually use them because they get overwritten.

This is what I found to help me

http://www.ozkary.com/2015/01/add-data-annotations-to-entity.html

also this

https://learn.microsoft.com/en-us/previous-versions/aspnet/ee256141(v=vs.98)

I don't pretend to understand it but here's a join the dots guide.

An example generated EF class looks like this:

public partial class Employee
{
    public int Emp_ID { get; set; }
    public string Emp_Name { get; set; }
    public Nullable<System.DateTime> Commencement_Date { get; set; }
}

Definitely do not edit this.

Instead you create a seperate class file (I called mine metadata.cs and put it in the Models folder) with this in it:

using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel;

namespace MyProject.Models
{
    [MetadataType(typeof(EmployeeMD))]  // new name for your metadata class
    public partial class Employee    // same name as your EF generated class
    {
    // Nothing in here
    }

    internal sealed class EmployeeMD // your metadata class
    {
    [Required]
    [StringLength(50, MinimumLength = 2, ErrorMessage = "Name required")]
    public string Emp_Name { get; set; }


    [DataType(DataType.Date)]
    [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
    public Nullable<System.DateTime> Commencement_Date { get; set; }
    }
}