Open Package Manager Console

Select Visual Studio menu item Tools | NuGet Package Manager | Package Manager Console.

Connection String

Add a connection string to the assembly used to manage database interactivity. This will be the Repositories assembly when using the Repository design pattern.

This is done by appending the following to the root node of App.config.

  <connectionStrings>
    <add name="SampleDbContext" connectionString="data source=.\LOCALDB; initial catalog=Sample; integrated security=SSPI" providerName="System.Data.SqlClient" />
  </connectionStrings>

If the name provided is the same as the DbContext. In this example SampleDbContext no additional steps are required, but if the names differ then a constructor must be created for the DbContext:

public class PlutoContext : BbContext
{
    public PlutoContext() : base("name=SampleDbContext")
}

Enable migrations

Using the following command:

PM> enable-migrations

Got Ah!

No context type was found in the assembly '...'.

If this error is returned then change the Default project to the project containing the <connectionString> value in its App.config. This is achieved by using a dropdown in the Package Manager Console.

A new folder titled Migrations will be created in the Solution.

Add a Migration

PM> add-migration InitialModel

Choose a name that is suitable to the changes made to the POCO code.

Inside Migrations you will see a new C# class. Its name is prefixed with an ISO date.

202002120900580_InitialModel.cs

Update the Database Schema

Once we have some migrations we can run the following:

PM> Update-Database

Overwrite a Migration

PM> add-migration InitialModel -force

Tip: Create small changes to the model and then create a migration. Think of migration as a commit to the source code depository.

For Example:

PM> add-migration AddIsSubscribedToCustomer

ASP.NET Identity Tables

If you have ASP.NET Identity as part of your project you will find that the migration class contains code to create these tables. The tables are:

• dbo.AspNetRoles
• dbo.AspNetUserRoles
• dbo.AspNetUsers
• dbo.AspNetUserLogins
• dbo.AspNetUserClaims

These tables are added to the database along with a _MigrationHistory Table. This table keeps track of migrations.