.NET Core Code First Migration Using Class Library

Steps

1. Create a new project.
2. Create Class Library.
3. Install Entity Framework.
4. Create Model.
5. Register context with dependency injection.
6. Create database.

Let’s get started.

Create a new project with Visual Studio 2015.

1. File > New > Project.
2. In the left menu > Visual C# > Web.
3. Choose ASP.NET Core Web Application (.NET Core).
   
   
   

Name it (MVCAngular2) and click OK. In our next step, we will see how to create a .NET Core Class Library & reference it to our application.

Add Class Library: SRC > Add > New Project.



From the left menu > Visual C# > .NET Core.



Choose Class Library (.NET Core), name it as MVCAngular2.Models, and click OK.

Project.json default template

{
    "version": "1.0.0-*",
    "dependencies": {
        "NETStandard.Library": "1.6.0"
    },
    "frameworks": {
        "netstandard1.6": {
            "imports": "dnxcore50"
        }
    }
}

We need to add command line tools for EF Core that include commands for Package Manager console.

"Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final"



There is an unsupported issue of EF Core 1.0.0-preview2-final with "NETStandard.Library": "1.6.0", so that we have changed the target framework to netstandard1.6 > netcoreapp1.0.

We have also specified the command line tool in tools section.

"tools": {
    "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final"
},

Finally, after modification.

{
    "version": "1.0.0-*",
    "dependencies": {
        "Microsoft.EntityFrameworkCore.SqlServer": "1.0.0",
        "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final"
    },
    "tools": {
        "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final"
    },
    "frameworks": {
        "netcoreapp1.0": {
            "imports": ["dotnet5.6", "portable-net45+win8"]
        }
    }
}

Packages will be automatically restored to our project Class Library.



Install Entity Framework

Now, let’s add the folder for context and entities.



Configuring DbContext

Let’s add a class to our context folder and name it StudentContext which is inherited from the base class DbContext. We need to reference Entity Framework Core library to our class.

using Microsoft.EntityFrameworkCore;

Here, in our context class, we have passed a generic version of DbContextOptions<T> with constructor argument of our context class.

public class StudentContext: DbContext
{
    public StudentContext(DbContextOptions < StudentContext > options): base(options) {}
}

Using base keyword, we have accessed the base class (DbContext) constructor to pass the options for the context from
DbContextOptions<T>.

base(options)

Let’s add Student Model in Entities folder.

public class Student
{
    public int StudentID {
        get;
        set;
    }
    public string StudentName {
        get;
        set;
    }
}

Now, in our DbContext Class, let’s define the dbSets with Student Model.

Finally DbContext class

public class StudentContext: DbContext
{
    public StudentContext(DbContextOptions < StudentContext > options): base(options) {}
    public DbSet < Student > Students {
        get;
        set;
    }
}

Register context with DI

Before registering the context, let’s reference the library to our Web application project.

• Reference > Add Reference > Solution > MVCAngular2.Models
  
  
  

Open Startup.cs file. In ConfigureServices method, we need to add AddDbContext method which uses Microsoft.Extensions.DependencyInjection to register StudentContext as a service.

public void ConfigureServices(IServiceCollection services)
{
    var connection = @ "Server=DESKTOP-4T79RA1;Database=EFCoreStudentDb;Trusted_Connection=True;";
    services.AddDbContext < StudentContext > (options => options.UseSqlServer(connection));
}

First, we have specified the connection info.

var connection = @"Server=DESKTOP-4T79RA1;Database=EFCoreStudentDb;Trusted_Connection=True;";

After that, we have registered the context using the connection info.

services.AddDbContext<StudentContext>(options => options.UseSqlServer(connection));

Here, UseSqlServer() is an extension method that configures the StudentContext to connect our SQL Server database.

Create database

Now, let’s create a database by using migrations.

1. Tools > NuGet Package Manager > Package Manager Console.
2. Type Add-Migration Initial to scaffold a migration, press Enter
3. Type Update-Database to apply the new migration to the database.

Add-Migration Initial




Update-Database



Now, open SSMS in order to explore our newly created database. As you can see from the below image.



Hope this will help.