EF Core v1

Entity Framework Core v1

EF Core v1 was released in 2016 and is a complete rewrite of Entity Framework (which dates back to v4.1 in 2011).
As of 2016, EF v6 Code First was still the recommended EF (EF Core v1.0.0 was missing some critical features, including lazy loading)

EF Core can run on .net Core (and thus not just on Windows), as well as the full framework. Some ADO providers only support the full framework (minimum 4.5.1).

Configuring

You can't use app/web.config (because .net Core dumped it). If you forget to configure you get an InvalidOperationException with the message "No database provider has been configured for this DbContext...."

public class MyContext : DbContext
{
    public DbSet<Product> Products { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer("Server=(localdb)\\MSSQLLocalDB;Integrated Security=true;Database=MyDatabase");
    }
}

Swapping from SqlServer to InMemory is a nice testing feature, but you'll have to inject options in tests with a constructor overload.

public class MyContext : DbContext
{
    public MyContext() { }

    public MyContext(DbContextOptions options) : base(options) { }

    public DbSet<Product> Products { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        if (!optionsBuilder.IsConfigured)
        {
            optionsBuilder.UseSqlServer("Server=(localdb)\\MSSQLLocalDB;Integrated Security=true;Database=MyDatabase");
        }
    }
}

In the tests, use the ctor overload to inject your options.

var builder = new DbContextOptionsBuilder<MyContext>();
builder.UseInMemoryDatabase();
var options = builder.Options;
var context = new MyContext(options);

Database Initialization

In EF v6 we had context.Database.SetInitializer(new CreateDatabaseIfNotExists<ModelContext>());
and for migrations, Database.SetInitializer(new MigrateDatabaseToLatestVersion<MyContext, Configuration>());

In EF Core v1, use:

For simple create-database: context.Database.EnsureCreated()
For migrations, Add-Migration "name" and Database.Migrate()
NB: does not work with InMemory - "Unable to resolve service for type ...IMigrator". If you swap between InMemory and a database, you may have to code around this.

In v6 you could put this in OnModelCreating. In EF Core you can't; it needs to be in Startup.cs or equivalent.

New command for reverse engineering a db: Scaffold-DbContext "connection string" Microsoft.EntityFrameworkCore.SqlServer
The EF v6 "Enable-Migrations" command has gone.
The _MigrationHistory table is renamed to __EFMigrationsHistory (it is not created with "EnsureCreated()").

Differences to EF v6

EF v6	EF Core v1
namespace System.Data.Entity	namespace Microsoft.Data.Entity
app/web.config configuration (based on ADO DbProviderFactory)	Code-based config
Database Initializers	Database.EnsureCreated(); or Database.Migrate();
DbContext.OnModelCreating(DbModelBuilder builder) Split mapping into classes with EntityTypeConfiguration	DbContext.OnModelCreating(ModelBuilder builder) No equivalent mapping classes- manually create static classes which take an EntityTypeBuilder
In fluent mapping, HasDatabaseGeneratedOption(DatabaseGeneratedOption.Computed)	.ValueGeneratedOnAddOrUpdate() also a .HasComputedColumnSql(sql)
In fluent mapping, IsMaxLength()	No equivalent.
Missing features in EF Core v1 Lazy loading (big one for an ORM!) Complex types Lots of other things...

static void

Entity Framework Core v1

Links

Configuring

Database Initialization

Differences to EF v6