At a Glance

  • Enterprise quality ORM framework for .NET
  • (Mostly) open source via Apache 2.0 license
  • Originally released in 2008, current version: 6
  • Database agnostic
  • Largely convention based
  • Distributed through NuGet

Key Features

  • LINQ to Entities (think: strongly typed SQL without the pain)
  • Enterprise features: transactions, concurrency, logging, wide database support
  • Async support
  • Supports N-Tier architecture (self-tracking, DTO model)
  • Migrations
  • Code First workflow



Model First

(Big) Model First

Code First

//Automatically maps to dbo.Orders table

public class Order {
   public int Id      {get;set;}
   public string Name {get;set;}
   public virtual Customer Customer {get;set;}
   public virtual List<Product> Products {get;set;}

Query Interface

using (EFContext context = new EFContext())
  var orders = context.Orders.Where(o=> o.UserId == userId);
ADO.NET w/o Entity Framework
List<Order> orders = new List<Order>();
using (SqlConnection connection = new SqlConnection("Server: 192.168...")) { conn.Open(); using (SqlCommand command = connection.CreateCommand()){ command.CommandText = "sp_GetOrders"; command.CommandType = CommandType.StoredProcedure; command.Parameters.AddWithValue("@UserID", userID); using(SqlDataReader = reader = command.ExecuteReader()){ while(reader.Read()){ Order newOrder = new Order(); newOrder.ID = Convert.ToInt32(reader["Id"]); newOrder.Name = reader["Name"].ToString(); orders.Add(newOrder); } } } }


  • Similar to Active Record
  • Not enabled by default
  • Supports "code first" migrations
  • Does not export schema
  • Supports seed data
  • Supports scripting migration
  • Doesn't play nicely with stored procedures

Enable-Migrations -EnableAutomaticMigrations
Add-Migration InitialCreate
Add-Migration AddOrderNotesColumn
Update Database


Loading Strategies

  • Eager - think inner/left join
  • Lazy - dynamically executed when accessed
  • Explicit - null until explicitly loaded

vs Active Record

  • Model is defined  as POCOs vs dynamic at runtime
  • "code first" migrations
  • Active Record objects are CUD aware (i.e. person.save) whereas in EF you have DbContext
  • Active Record classes inherit from ActiveRecord::Base whereas EF classes do not (need) to inherit from base class


  • Testability (mocking DbContext not easy)
  • Performance
  • Separation of concerns (biz logic?)
  • Produced SQL complex / inefficient sometimes
  • Bloatware (1,000,000+ lines of code)


  • Performance improvements
  • Stored procedures for CUD
  • Code based configuration enhancements
  • Enum support
  • Async queries built-in
  • Testability improvements
  • Query interception (logging, custom hooks ,etc.)
  • Connection resilience


  • Estimated release: Fall 2014
  • Completely new codebase
  • Fully open source
  • Wider platform support including Azure and Mono/Xamarin (Linux/Mac)
  • Code First Workflow primarily supported
  • Will not contain ObjectContext, Entity SQL, EntityConnection, EntityCommand, etc.