DbContext and DbSet

What is DbContext?

DbContext represents a session with the database. It’s responsible for:

• Querying data
• Saving changes
• Configuring the model
• Managing relationships and tracking entities

Defining a Custom DbContext

using Microsoft.EntityFrameworkCore;

public class AppDbContext : DbContext
{
    public DbSet<Product> Products { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder options)
        => options.UseSqlServer("your-connection-string");
}

What is DbSet?

A DbSet<T> corresponds to a table in the database and provides access to all operations for that entity — querying, inserting, updating, and deleting.

Each DbSet should match one model (class).

Querying Data with DbSet

using var context = new AppDbContext();

var products = context.Products.ToList();

foreach (var product in products)
{
    Console.WriteLine(product.Name);
}

Adding a New Record

var newProduct = new Product { Name = "Mouse" };
context.Products.Add(newProduct);
context.SaveChanges();

Change Tracking

EF Core tracks changes made to entities so it knows what needs to be saved. You can view tracking info via:

var state = context.Entry(newProduct).State; // Added, Modified, etc.

DbContext and DbSet form the foundation of EF Core. They manage how your models interact with the database. In the next lesson, we’ll perform full CRUD operations and practice creating, reading, updating, and deleting records.