Working with Entity Framework Core in C#

Entity Framework Core (EF Core) is a powerful and lightweight Object-Relational Mapping (ORM) framework for .NET applications. It simplifies database operations by allowing developers to work with .NET objects rather than writing raw SQL queries. In this tutorial, we’ll explore the fundamentals of using Entity Framework Core in C#.

Getting Started

Installing Entity Framework Core

Before you can start using EF Core, you need to install the necessary packages. In your project, open the NuGet Package Manager and install the Microsoft.EntityFrameworkCore and Microsoft.EntityFrameworkCore.SqlServer packages.

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

Creating a DbContext

The DbContext is the heart of EF Core. It represents a session with the database and allows you to perform operations like querying, inserting, updating, and deleting entities.

public class AppDbContext : DbContext
{
    public DbSet<User> Users { get; set; }
    // Add other DbSet properties for your entities here

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

Replace User with your own entity and provide your database connection string.

Defining Entities

Entities are C# classes that represent tables in your database. Each property in the class corresponds to a column in the table.

public class User
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Email { get; set; }
}

Performing CRUD Operations

Creating Records

using (var context = new AppDbContext())
{
    var newUser = new User { Name = "John Doe", Email = "john@example.com" };
    context.Users.Add(newUser);
    context.SaveChanges();
}

Reading Records

using (var context = new AppDbContext())
{
    var users = context.Users.ToList();
    foreach (var user in users)
    {
        Console.WriteLine($"{user.Id}: {user.Name} - {user.Email}");
    }
}

Updating Records

using (var context = new AppDbContext())
{
    var user = context.Users.FirstOrDefault(u => u.Id == 1);
    if (user != null)
    {
        user.Email = "john.doe@newdomain.com";
        context.SaveChanges();
    }
}

Deleting Records

using (var context = new AppDbContext())
{
    var user = context.Users.FirstOrDefault(u => u.Id == 1);
    if (user != null)
    {
        context.Users.Remove(user);
        context.SaveChanges();
    }
}

Querying with LINQ

EF Core allows you to use LINQ (Language Integrated Query) to write expressive and powerful queries.

using (var context = new AppDbContext())
{
    var users = context.Users
        .Where(u => u.Name.Contains("John"))
        .OrderBy(u => u.Name)
        .ToList();
}

Conclusion

Entity Framework Core provides a seamless way to interact with databases in C# applications. With its powerful features and simplicity, it has become a popular choice for .NET developers. By following this tutorial, you’ve gained a solid foundation for working with EF Core, enabling you to build robust and efficient data-driven applications.