What is EF Core and its benefits as an ORM?

Entity Framework Core (EF Core) is a modern, lightweight, extensible, and cross-platform Object-Relational Mapper (ORM) for .NET. It enables .NET developers to work with a database using .NET objects, eliminating the need to write most of the data-access code themselves. EF Core supports many database engines like SQL Server, PostgreSQL, MySQL, SQLite, and more.

This tutorial explores EF Core's core concepts and highlights its significant benefits as an ORM.

Understanding ORM and its Role

An Object-Relational Mapper (ORM) is a programming technique that converts data between incompatible type systems using object-oriented programming languages. In essence, it allows you to interact with a database using your programming language's objects instead of writing raw SQL queries. This simplifies database operations and improves code maintainability.

What is Entity Framework Core (EF Core)?

EF Core is Microsoft's recommended ORM for modern .NET applications. It provides a set of APIs that allows you to:

• Model your database structure: Define your database tables (entities) as C# classes.
• Query data: Retrieve data from the database using LINQ (Language Integrated Query).
• Persist data: Save, update, and delete data in the database using your .NET objects.
• Manage schema changes: Apply migrations to update your database schema based on changes in your entity models.

Key Benefits of Using EF Core as an ORM

• Reduced Code: EF Core eliminates the need to write repetitive data access code, such as SQL queries and data mapping logic. This significantly reduces the amount of code you need to write and maintain.
• Improved Productivity: By abstracting away database complexities, EF Core allows developers to focus on the business logic of their applications.
• Type Safety: LINQ queries are type-safe, meaning that the compiler can catch errors related to data types at compile time, preventing runtime errors.
• Database Independence: EF Core supports multiple database providers, allowing you to switch databases without significant code changes.
• Object-Oriented Programming: EF Core allows you to work with data using .NET objects, making your code more readable, maintainable, and testable.
• Simplified Data Access: EF Core provides a consistent and intuitive API for performing data access operations.
• Change Tracking: EF Core automatically tracks changes to your entities, making it easy to persist those changes to the database.
• Migration Support: EF Core provides a migration feature that allows you to manage database schema changes in a controlled and automated manner.

Basic Example: Defining an Entity

This code defines a simple `Blog` entity with properties for `BlogId`, `Title`, and `Content`. EF Core will use this class to map to a corresponding table in the database.

public class Blog
{
    public int BlogId { get; set; }
    public string Title { get; set; }
    public string Content { get; set; }
}

Basic Example: Configuring the DbContext

This code defines a `DbContext` class, which represents a session with the database. The `BloggingContext` class inherits from `DbContext` and defines a `DbSet` property, which represents the collection of `Blog` entities. The `OnConfiguring` method configures the database connection using SQL Server. Remember to install the necessary EF Core NuGet packages, including `Microsoft.EntityFrameworkCore.SqlServer`.

using Microsoft.EntityFrameworkCore;

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

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer("Server=(localdb)\mssqllocaldb;Database=MyDatabase;Trusted_Connection=True;");
    }
}

Basic Example: Querying Data

This code retrieves all `Blog` entities from the database and prints their titles to the console. It uses LINQ to query the data and the `ToList()` method to execute the query and retrieve the results.

using (var context = new BloggingContext())
{
    var blogs = context.Blogs.ToList();
    foreach (var blog in blogs)
    {
        Console.WriteLine(blog.Title);
    }
}

Basic Example: Adding Data

This code creates a new `Blog` entity, adds it to the `Blogs` DbSet, and saves the changes to the database. The `SaveChanges()` method persists the changes to the database.

using (var context = new BloggingContext())
{
    var blog = new Blog { Title = "My New Blog", Content = "This is my first blog post." };
    context.Blogs.Add(blog);
    context.SaveChanges();
}

Real-Life Use Case: E-commerce Application

In an e-commerce application, EF Core can be used to manage product catalogs, customer orders, shopping carts, and user accounts. Each entity in the database (e.g., `Product`, `Order`, `Customer`) can be represented as a C# class, and EF Core can be used to perform CRUD (Create, Read, Update, Delete) operations on these entities.

Best Practices

• Use Asynchronous Operations: Use asynchronous methods (e.g., `ToListAsync()`, `SaveChangesAsync()`) to avoid blocking the main thread and improve application responsiveness.
• Use Database Context Pooling: Database context pooling can improve performance by reusing database connections.
• Use No-Tracking Queries: Use no-tracking queries when you only need to read data and don't intend to modify it. This can improve performance by reducing the amount of memory used by EF Core.
• Optimize Queries: Use indexes and other techniques to optimize database queries.
• Handle Concurrency: Implement concurrency handling to prevent data loss when multiple users are modifying the same data.

Interview Tip

Be prepared to discuss the advantages and disadvantages of using an ORM like EF Core. Also, be prepared to answer questions about different database providers, LINQ queries, and database migrations.

When to use EF Core

EF Core is a good choice when you want to simplify data access, improve code maintainability, and work with data using .NET objects. It is particularly well-suited for applications with complex data models and a large number of data access operations.

Memory Footprint

EF Core's memory footprint can vary depending on the size of your data model and the number of entities you are working with. Using no-tracking queries and optimizing queries can help reduce the memory footprint. Context pooling also helps to optimize memory usage by reusing DbContext instances.

Alternatives

Alternatives to EF Core include:

• Dapper: A lightweight ORM that provides high performance and control over SQL queries.
• ADO.NET: A low-level data access technology that allows you to interact directly with the database.
• NHibernate: A mature and feature-rich ORM that supports a wide range of databases and mapping scenarios.

Pros

• Simplified data access.
• Improved code maintainability.
• Type safety.
• Database independence.
• Object-oriented programming.
• Change tracking.
• Migration support.

Cons

• Performance overhead compared to raw SQL queries.
• Can be complex to configure and use for advanced scenarios.
• May generate inefficient SQL queries if not used properly.