Entity Framework Core Overview

Entity Framework Core (EF Core) is a modern, cross-platform, open-source version of the popular Entity Framework data access technology. EF Core enables .NET developers to work with a database using domain-specific objects that are essentially .NET classes. This approach is known as the Object-Relational Mapper (ORM) pattern.

What is Entity Framework Core?

EF Core simplifies data access in .NET applications. It provides a set of APIs and tools that allow you to:

Map .NET Objects to Database Tables: Define your data models as C# classes and EF Core will handle the mapping to your database schema.
Query Data: Write LINQ (Language Integrated Query) queries against your domain models, and EF Core translates them into efficient SQL queries.
Save Data: Easily add, update, and delete data in your database by manipulating your .NET objects.
Database Migrations: Manage changes to your database schema over time as your application evolves.
Cross-Platform Support: Run your EF Core applications on Windows, macOS, and Linux.

Key Features of EF Core

Lightweight and Extensible: Designed to be more performant and flexible than its predecessors.
LINQ Support: Powerful and intuitive querying capabilities using LINQ.
Change Tracking: Automatically detects changes to your entities and generates appropriate SQL commands.
Database Providers: Supports a wide range of databases including SQL Server, PostgreSQL, MySQL, SQLite, Azure Cosmos DB, and more.
T4 Templates: Generate model code from an existing database.
Database-First, Code-First, Model-First: Supports various development workflows.

Core Concepts

Understanding these core concepts will help you get started with EF Core:

DbContext: The primary class that represents a session with the database and allows you to query and save data.
DbSet: Represents a collection of entities of a given type within a DbContext. It's a gateway to querying and saving data for that entity type.
Entities: Plain old C# objects (POCOs) that represent tables in your database.
Model: The collection of DbContext and entity types.
Data Annotations and Fluent API: Mechanisms for configuring your model, such as defining primary keys, relationships, and data types.

Example: A Simple Query

Here's a basic example of how to query data using EF Core:


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

    foreach (var blog in blogs)
    {
        Console.WriteLine($"Found blog: {blog.Url}");
    }
}

Next Steps

To dive deeper into EF Core, explore the following resources: