Entity Framework

Entity Framework (EF) is Microsoft’s flagship Object‑Relational Mapping (ORM) framework for .NET. It enables developers to work with a database using .NET objects, eliminating most of the data-access code they would usually need to write.

On this page Overview Getting Started Model Creation Queries Migrations Performance Tips API Reference

Overview

EF provides the following features:

Code‑First and Database‑First model creation.
LINQ queries with compile‑time checking.
Change tracking and automatic updates.
Support for multiple database providers (SQL Server, SQLite, PostgreSQL, etc.).

Getting Started

Install the EF Core package via NuGet:

dotnet add package Microsoft.EntityFrameworkCore

For SQL Server support:

dotnet add package Microsoft.EntityFrameworkCore.SqlServer

Model Creation

Define your entity classes and a DbContext subclass:

using Microsoft.EntityFrameworkCore;

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

    protected override void OnConfiguring(DbContextOptionsBuilder options)
        => options.UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=Blogging;Trusted_Connection=True;");
}

public class Blog
{
    public int BlogId { get; set; }
    public string Url { get; set; }
    public List<Post> Posts { get; } = new();
}

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; }
}

Queries

Typical LINQ query examples:

// Retrieve blogs with at least one post
var blogs = await context.Blogs
    .Where(b => b.Posts.Any())
    .ToListAsync();

// Load a blog with its posts (eager loading)
var blog = await context.Blogs
    .Include(b => b.Posts)
    .FirstOrDefaultAsync(b => b.BlogId == 1);

Migrations

Manage schema changes using the migrations CLI:

// Add a new migration
dotnet ef migrations add AddPostPublishedDate

// Apply pending migrations
dotnet ef database update

Performance Tips

Use AsNoTracking() for read‑only queries.
Prefer compiled queries for high‑frequency operations.
Batch multiple inserts/updates with SaveChanges to reduce round‑trips.
Paginate large result sets with Skip and Take.

API Reference

Explore the full API documentation: