Code First migration in asp.net MVC 4 - Free Asp.Net,MVC,AngularJs,Jquery,Javascript,Sql Server,WCF,Entity framework snippets and tutorial

Code First migration in asp.net MVC 4

Introduction: In this article I will explain how we can enable Code First migration in asp.net MVC 4

Description:

Migration is used to backup our database when we are going to develop application using code first approach in asp.net MVC.
I have a class named Student_Detail.cs in Models:
public class Student_Detail
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Subject { get; set; }
        public int Marks { get; set; }
    } 
Now I add a new property in this class for student address.
public class Student_Detail
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Subject { get; set; }
        public int Marks { get; set; }
        public string Address { get; set; }
    } 
Build the project and run the application. You got an Exception:
“The model backing the 'ProjectContext' context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269).”
See attached snapshot:

Code First migration
                                                                                         (Click to enlarge)
If you see exception/error carefully it suggests the solution:
Use Code First Migrations to update the database
Step 1: To update database using Code first Migration go to Tools>>Library Package Manager >> Package Manager Console as shown in snapshot:

Code First migration
                                                                                               (Click to enlarge)
Package Manager Console will be open and type the given command:
enable-migrations
Hit the enter button. It will show output of all context you have in project. Copy the context for that you want to enable migration. Here I run the following command:
PM> Enable-Migrations -ContextTypeName MVCAPPLICATION.Models.ProjectContext
As command execute it will show you enabled message for context as show in attached snapshot:

Code First migration
                                                                                             (Click to enlarge)
It will create Migration folder in project with configuration.cs (seed method) and InitialCreate target migration (up and down methods) see attached snapshot:

Code First migration

                                                                                            (Click to enlarge)
Step 2: After that in configuration.cs file change the AutomaticMigrationsEnabled to true:
public Configuration()
        {
            AutomaticMigrationsEnabled = true;
        }

Step 3: open Global.asax file and add the namespace:

using MVCAPPLICATION.Models;
using System.Data.Entity;

Add the given code to Application_Start in Global.asax file:
Database.SetInitializer<ProjectContext>(null);

Step 4: Run the command in Package Manager Console:
update-database


Now you see a column has been added to table in database. Add the column in views files or add a new Controller. Run the application and see the result.

I hope this article helps you to use code first Migration to update the database.

Is this article helpful for you?

If yes post your comment to appreciate my work and fell free to contact me. You can like me on Facebook, Google+, Linkedin and Twitter via hit on Follow us Button and also can get update follow by Email.

What do you think about this article?

If you found this article useful, please share and follow on Facebook, Twitter, Google Plus and other social media websites. To get free updates subscribe to newsletter. Please put your thoughts and feedback in comments section.

Share this

Share on FacebookTweet on TwitterPlus on Google+


EmoticonEmoticon