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Entity Framework Core Migrations

Entity Framework Core is the new data access technology baked into .net core. It is cross platform and supports multiple relational databases. It supports both targeted upgrading and downgrading. Migrations can be executed from the PMC or via the dotnet CLI. The dotnet CLI makes it highly scriptable and CI friendly.

About

Installation

dotnet add .\src\Example.CLI\Example.CLI.csproj package Microsoft.EntityFrameworkCore

This is just a base class library, to interact with a database you must also install a package specific to that database.

Sql Server

dotnet add .\src\Example.CLI\Example.CLI.csproj package Microsoft.EntityFrameworkCore.sqlserver

This will add a reference to the sql server entity framework package to the given project file. This only gives access to execute entity framework functionality at runtime.

dotnet add .\src\Example.CLI\Example.CLI.csproj package Microsoft.entityframeworkcore.sqlserver.design

This adds a reference to the design time components for entity framework.

dotnet add .\src\Example.CLI\Example.CLI.csproj package Microsoft.EntityFrameworkCore.tools

Enables Package Manager Console integration for interacting with EF similar to previous versions of the framework.

dotnet add .\src\Example.CLI\Example.CLI.csproj package Microsoft.entityframeworkcore.tools.dotnet

Adds a reference to the dotnet CLI tools for interacting with EF. Due to a bug in the CLI implementation, this reference will be added wrong. You must edit the reference so that it looks like this:

<ItemGroup>
  <DotNetCliToolReference Include="Microsoft.EntityFrameworkCore.Tools.DotNet" Version="1.0.0" />
</ItemGroup>

Sqlite

dotnet add .\src\Example.CLI\Example.CLI.csproj package Microsoft.EntityFrameworkCore.Sqlite

Non-Microsoft data stores are easily supported using their integration libraries instead of the Sql Server version.

Example Migration

using System;
using System.Collections.Generic;
using Microsoft.EntityFrameworkCore.Migrations;

namespace Migrations.EF.Core.Migrations
{
    public partial class Init : Migration
    {
        protected override void Up(MigrationBuilder migrationBuilder)
        {

        }

        protected override void Down(MigrationBuilder migrationBuilder)
        {

        }
    }
}

CLI Based Execution

All Entity Framework migration commands must be excuted from inside Visual Studio's Package Manager Console or the CLI. CLI integration easy for CI systems to interact with the migrations to deploy them to an environment or generate data change scripts at build time.

Applying Migrations to Database

dotnet ef database update

Will connect to the database and apply any migrations that have not already been applied.

Creating and Destroying Migrations

dotnet ef migrations add MeaningfullName

Will look at the current state of our model and generate migration for any changes from the previous migration.

dotnet ef migrations remove MeaningfullName

Will attempt to remove the migration from the project.

Generating Change Scripts

dotnet ef migrations script -i -o "Script0001-version_1.sql"

Will generate an idempotent sql script containging all the migrations. This script can be run on an empty database or an existing database, only the missing migrations will be applied.

dotnet ef migrations script -o "Script0001-drop_tables.sql" Current Init

Will connect to the currently configured database and generate destructive scripts to drop all migrations applied from the Current migration to the Init migration.

Note: Full CLI reference is located here. You can do some cool stuff with the CLI.