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Entity Framework Tutorial for .NET

Introduction​

Entity Framework (EF) is an Object-Relational Mapping (ORM) framework for .NET that allows developers to work with databases using C# objects. EF simplifies database operations by eliminating the need to write raw SQL for common tasks, providing an easy-to-use framework to interact with data.

There are two main versions:

  • Entity Framework 6 (EF6): The version designed for the .NET Framework.
  • Entity Framework Core (EF Core): A modern, cross-platform, and lightweight version designed for .NET Core and .NET 5+.

In this tutorial, we will focus on Entity Framework Core, as it is the most widely used version today.

Prerequisites​

Before starting, ensure you have the following:

  • .NET SDK installed on your system.
  • A code editor, like Visual Studio Code or Visual Studio.
  • SQL Server (or another database) installed locally or using a cloud service (like Azure SQL Database).

Step 1: Creating a New .NET Core Project​

  1. Open your terminal or command prompt.

  2. Run the following command to create a new console application:

    dotnet new console -n EFCoreTutorial
    cd EFCoreTutorial

  3. Add Entity Framework Core to your project:

    dotnet add package Microsoft.EntityFrameworkCore
    dotnet add package Microsoft.EntityFrameworkCore.SqlServer
    dotnet add package Microsoft.EntityFrameworkCore.Design

Step 2: Create the Data Model​

Now, let's define a simple model class to represent a database table. For example, a Product class:

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
}

This class will be used by EF Core to map to a database table named Products.

Step 3: Create a DbContext Class​

A DbContext represents a session with the database and allows querying and saving data. Create a new class AppDbContext that inherits from DbContext:

using Microsoft.EntityFrameworkCore;

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

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer("Your_Connection_String_Here");
    }
}

Replace "Your_Connection_String_Here" with your actual SQL Server connection string.

Step 4: Perform Database Migrations​

EF Core provides migrations to keep your database schema in sync with your model. Here’s how to create the database schema:

  1. In the terminal, run:

    dotnet ef migrations add InitialCreate

    This will create the first migration to create the database schema.

  2. To apply the migration and create the database, run:

    dotnet ef database update

Step 5: Insert Data into the Database​

Now, let’s insert some sample data into the database using EF Core. Update the Program.cs file:

using (var context = new AppDbContext())
{
    // Ensure the database is created
    context.Database.EnsureCreated();

    // Add a new product
    var product = new Product
    {
        Name = "Laptop",
        Price = 1200.00m
    };
    context.Products.Add(product);
    context.SaveChanges();
}

Step 6: Query Data from the Database​

To retrieve data from the database, you can use LINQ queries with EF Core:

using (var context = new AppDbContext())
{
    var products = context.Products.ToList();

    foreach (var product in products)
    {
        Console.WriteLine($"Id: {product.Id}, Name: {product.Name}, Price: {product.Price}");
    }
}

Step 7: Update and Delete Data​

Update Data​

To update a product:

using (var context = new AppDbContext())
{
    var product = context.Products.First();
    product.Price = 1300.00m;
    context.SaveChanges();
}

Delete Data​

To delete a product:

using (var context = new AppDbContext())
{
    var product = context.Products.First();
    context.Products.Remove(product);
    context.SaveChanges();
}

Conclusion​

This simple tutorial covered the basics of Entity Framework Core in .NET, including setting up a DbContext, creating a model, performing database migrations, and basic CRUD operations. EF Core makes working with databases in .NET easy and efficient, allowing developers to focus more on writing code and less on SQL.

For more advanced topics, explore:

  • Relationships (One-to-Many, Many-to-Many)
  • Data Seeding
  • Custom Queries and Raw SQL
  • Performance Optimization

Resources​

Content Review​

The content in this repository has been reviewed by chevp. Chevp is dedicated to ensuring that the information provided is accurate, relevant, and up-to-date, helping users to learn and implement programming skills effectively.

About the Reviewer​

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