Modify Model structure without changing existing EF 4.x Generated Model in Database First Approach

Question

I'm using ASP.NET MVC 3.0 Database First approach with EF 4.x. Models are generated with EF 4.x DBContext Generator. Now I want to change model structure but don't want to change existing model because if database is modified I have to generate model again so the changes will be gone. I think it should be done by overriding partial classes but not clear. Is there any example to do it? what is the best way to implement it?

Edit: I have to add some additional validations in some Models, not all. I want to create independent models which overrides the generated classes and in case if EF models are regenerated there is no harm on our customized models.

if I undrestand you correctly you want to update certain model class but you do not want it to be erased when you update the whole model — COLD TOLD, Apr 12 '12 at 06:01
when you update model update only classes/tables that you think will change — COLD TOLD, Apr 12 '12 at 07:29

Yorgo · Accepted Answer · 2012-04-12T08:16:22.903

1

you can change the *.tt file for generating objects from model. What do you want to change objects.
You can create partial classes like this

namespace MyProject.Data{ public partial class User{} }

but your partial class should be the same namespace of EF created classes

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;

    [MetadataType(typeof(UserMetadata))]
    public partial class User : IEntity
    {
        internal class UserMetadata
        {
            [DisplayName("User Name")]
            public virtual string UserName
            {
                get;
                set;
            }
            [DisplayName("First Name")]
            public virtual string FirstName
            {
                get;
                set;
            }

            [DisplayName("LastName")]
            public virtual string LastName
            {
                get;
                set;
            }
        }
    }

edited Apr 12 '12 at 08:16

answered Apr 12 '12 at 06:08

Yorgo

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I've to change specific models only...so couldn't change template. – Brij Apr 12 '12 at 06:24
then use second solution and create partial class for specific classes – Yorgo Apr 12 '12 at 06:26
How can I change existing property annotations in new class? I've to keep EF generated class also. – Brij Apr 12 '12 at 07:50
One Quick Question ... Do we need EF *.tt generated Classes? If I'm creating separate viewmodels for each. – Brij Apr 13 '12 at 09:51
if you create viewmodels than you should not need to partial classes – Yorgo Apr 13 '12 at 10:40

Modify Model structure without changing existing EF 4.x Generated Model in Database First Approach

1 Answers1