Entity Framework Core

Note

This documentation is for EF Core. For EF6.x, see Entity Framework 6.

Entity Framework (EF) Core is a lightweight, extensible, and cross-platform version of the popular Entity Framework data access technology.

EF Core is an object-relational mapper (O/RM) that enables .NET developers to work with a database using .NET objects. It eliminates the need for most of the data-access code that developers usually need to write. EF Core supports many database engines, see Database Providers for details.

If you like to learn by writing code, we'd recommend one of our Getting Started guides to get you started with EF Core.

Get Entity Framework Core

Install the NuGet package for the database provider you want to use. See Database Providers for information.

PM>  Install-Package Microsoft.EntityFrameworkCore.SqlServer

The Model

With EF Core, data access is performed using a model. A model is made up of entity classes and a derived context that represents a session with the database, allowing you to query and save data. See Creating a Model to learn more.

You can generate a model from an existing database, hand code a model to match your database, or use EF Migrations to create a database from your model (and evolve it as your model changes over time).

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

namespace Intro
{
    public class BloggingContext : DbContext
    {
        public DbSet<Blog> Blogs { get; set; }
        public DbSet<Post> Posts { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=MyDatabase;Trusted_Connection=True;");
        }
    }

    public class Blog
    {
        public int BlogId { get; set; }
        public string Url { get; set; }
        public int Rating { get; set; }
        public List<Post> Posts { get; set; }
    }

    public class Post
    {
        public int PostId { get; set; }
        public string Title { get; set; }
        public string Content { get; set; }

        public int BlogId { get; set; }
        public Blog Blog { get; set; }
    }
}

Querying

Instances of your entity classes are retrieved from the database using Language Integrated Query (LINQ). See Querying Data to learn more.

using (var db = new BloggingContext())
{
    var blogs = db.Blogs
        .Where(b => b.Rating > 3)
        .OrderBy(b => b.Url)
        .ToList();
}

Saving Data

Data is created, deleted, and modified in the database using instances of your entity classes. See Saving Data to learn more.

using (var db = new BloggingContext())
{
    var blog = new Blog { Url = "http://sample.com" };
    db.Blogs.Add(blog);
    db.SaveChanges();
}