Overview

What is entity framework core?

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

EF Core can serve as an object-relational mapper (O/RM), which:

• Enables .NET developers to work with a database using .NET objects.

• Eliminates the need for most of the data-access code that typically needs to be written.

EF Core supports many database engines, see Database Providers for details.

The model

With EF Core, data access is performed using a model. A model is made up of entity classes and a context object that represents a session with the database. The context object allows querying and saving data.

EF supports the following model development approaches:

• Generate a model from an existing database.

• Hand code a model to match the database.

• Once a model is created, use EF Migrations to create a database from the model. Migrations allow evolving the database as the model changes.

Querying

Instances of your entity classes are retrieved from the database using Language Integrated Query (LINQ)

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.

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