#Model builder entity framework install
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Creating Migration if Entities and Dbcontext Files are in a Separate Project Now, we can delete our database (just to simulate the initial state in the SQL server) and only apply our migration again (we don’t need to create it, it is already created). We should make sure to have the SQL method in the Down() method to execute the opposite actions if we decide to remove our migration. Table.PrimaryKey('PK_Student', x => PROCEDURE M圜ustomProcedure

So, let’s open the InitialMigration class and modify it by adding our custom code: public partial class InitialMigration : Migration

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One of those methods is the Sql method that we can use to add the custom code we like. We can use the MigrationBuilder parameter to access the broad range of methods that can help us in the process.

If needed, we can add our custom code, too. But all the code in those methods is generated by EF Core. We have already explained the purpose of the Up() and Down() methods in our InitialMigration file. If we have multiple migrations to apply, then they will be applied in the exact order they are created. Well, it stores a unique Id in the _EFMigrationsHistory, which is a unique name of the migration file created with the migration, and never executes files with the same name again:Įach migration is applied within an SQL transaction, which means that whole migration either succeeds or fails. So, this means that if we create another migration in our code and apply it, EF Core will apply only the newly created migration.īut how does EF Core know what migration needs to be applied? EF Core uses this table to track all the applied migrations. If we inspect our database, we are going to find another created table: _EFMigrationsHistory. There are few more important facts we have to know about EF Core’s migrations. There are several ways of applying migrations (Using SQL scripts, using Database.Migrate method, or using command line methods), and as we did with the creation, we are going to use the command line methods approach. Applying Created MigrationĪfter we have successfully created our migration, we have to apply it for changes to take effect in the database. As an opposite action, the Down() method will execute commands when we remove this migration (in this case it will just drop this created table). The Up() method consists of commands that will be executed when we apply this migration. This file has two methods conveniently named Up() and Down. Protected override void Down(MigrationBuilder migrationBuilder) Table.PrimaryKey('PK_Student', x => x.StudentId) IsRegularStudent = table.Column(nullable: false, defaultValue: true) Name = table.Column(maxLength: 50, nullable: false), StudentId = table.Column(nullable: false), Protected override void Up(MigrationBuilder migrationBuilder) So, if you have followed all the steps from the previous articles, the content of the InitialMigration file should look like this: public partial class InitialMigration : Migration The other two files: InitialMigration and InitialMigration.Designer are files that contain and describe the newly created migration. The ApplicationContextModelSnapshot.cs file holds the model of the database and it is updated every time a new migration is added. After that, it creates three different files in the Migrations folder: The first thing it does is inspect our class, associated entity classes (in this case only the Student class), and any configuration we applied. Actions that Take Place Behind the SceneĪfter we execute the Add-Migration command EF Core does several things behind the scenes to prepare our migration.

#Model builder entity framework series

If you are following this series from the start, then you already have the Microsoft.EntityFrameworkCore library installed.Īfter we press the Enter key, our migration will be completed.

#Model builder entity framework install

Therefore, we have to install the library.

Adding or removing the DbSet properties from the context classįrom ASP.NET Core 3.0, EF Core tools required for migrations are not preinstalled.

Changes in the properties of the model class.

As we already said, our database schema must be aligned with the database model and every change in a database model needs to be migrated to the database itself. The migration process has two steps: Creating migration and Applying migration.

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Using migrations is a standard way to create and update a database with Entity Framework Core. To see all the basic instructions and complete navigation for this series, visit Entity Framework Core with ASP.NET Core Tutorial.

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To download the source code for this article, you can visit our GitHub repository.