Entity Framework Core: An Overview

Entity Framework Core (EF Core) is a modern, open-source, and cross-platform version of the popular Entity Framework data access technology. It's an Object-Relational Mapper (ORM) that enables .NET developers to work with databases using .NET objects, abstracting away much of the underlying SQL code. This makes database interactions more intuitive and productive, especially within the C# .NET ecosystem and when integrating with cloud platforms like Azure.

What is an ORM?

An ORM bridges the gap between object-oriented programming and relational databases.

Object-Relational Mappers (ORMs) like EF Core translate data between incompatible type systems of object-oriented languages (like C#) and relational databases (like SQL Server or PostgreSQL). This allows developers to interact with database tables and rows as if they were C# classes and objects.

In object-oriented programming, data is typically represented as objects with properties and methods. Relational databases, on the other hand, store data in tables with rows and columns. These two paradigms are fundamentally different. An ORM acts as a translator, mapping your C# classes to database tables and their properties to table columns. This mapping allows you to perform database operations (like querying, inserting, updating, and deleting) using familiar C# syntax, without needing to write raw SQL for most common tasks.

Key Concepts in EF Core

Understanding a few core concepts will help you get started with EF Core:

DbContext

The

code

DbContext

class is the primary gateway to your database. It represents a session with the database and allows you to query and save data. You typically create a class that inherits from

code

DbContext

and defines

code

DbSet

properties for each entity (table) you want to interact with.

DbSet<TEntity>

code

DbSet

represents a collection of entities of a specific type. Think of it as a table in your database. You can use LINQ (Language Integrated Query) to query

code

DbSet

properties to retrieve data from the database.

Entities

Entities are plain old C# objects (POCOs) that represent the data you're working with. For example, a

code

Product

entity might have properties like

code

Id

code

Name

, and

code

Price

. EF Core maps these entities to database tables.

Migrations

Migrations are a feature of EF Core that allows you to evolve your database schema over time as your application's data model changes. They are essentially version-controlled scripts that EF Core generates to update your database schema. This is crucial for maintaining consistency between your application code and your database structure.

EF Core and Azure Integration

EF Core is a natural fit for developing applications deployed on Azure. It seamlessly integrates with Azure SQL Database, Cosmos DB, and other Azure data services. This allows you to leverage the power of the cloud for your data storage and management needs, while using familiar .NET development patterns.

EF Core simplifies data access, making it easier to build robust .NET applications that can scale with Azure services.

Common EF Core Operations

Here are some fundamental operations you'll perform with EF Core:

Querying Data

You can query data using LINQ. For example, to get all products with a price greater than 50:

csharp

var expensiveProducts = context.Products.Where(p => p.Price > 50).ToList();

Adding Data

To add a new entity, you create an instance of your entity class, add it to the appropriate

code

DbSet

, and then call

code

SaveChanges()

csharp

var newProduct = new Product { Name = "Gadget", Price = 75.00 };
context.Products.Add(newProduct);
context.SaveChanges();

Updating Data

To update an entity, you typically retrieve it, modify its properties, and then call

code

SaveChanges()

csharp

var productToUpdate = context.Products.Find(1);
if (productToUpdate != null) {
    productToUpdate.Name = "Super Gadget";
    context.SaveChanges();
}

Deleting Data

To delete an entity, you retrieve it and then call

code

Remove()

on the

code

DbSet

, followed by

code

SaveChanges()

csharp

var productToDelete = context.Products.Find(2);
if (productToDelete != null) {
    context.Products.Remove(productToDelete);
    context.SaveChanges();
}

What is the primary class in EF Core used to interact with the database?

The DbContext class.

What feature of EF Core helps manage database schema changes over time?

Migrations.

This diagram illustrates the core components of EF Core and their relationships. The DbContext acts as the central hub, managing DbSet collections. Each DbSet represents a table and holds instances of your application's Entities. Operations like querying, adding, updating, and deleting data are performed through the DbContext, which then translates these actions into SQL commands executed against the database. Migrations are a separate process that modifies the database schema based on changes to your entities and DbContext.

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Learning Resources

Entity Framework Core Documentation(documentation)

The official and most comprehensive documentation for Entity Framework Core, covering installation, concepts, and advanced features.

Get Started with Entity Framework Core(tutorial)

A step-by-step guide to setting up and using EF Core in a .NET application, perfect for beginners.

EF Core: What's New(blog)

Stay updated with the latest features, improvements, and announcements related to Entity Framework Core from the official .NET blog.

Entity Framework Core on Wikipedia(wikipedia)

An overview of Entity Framework, including its history, features, and its evolution into Entity Framework Core.

Introduction to Entity Framework Core - Microsoft Learn(tutorial)

A structured learning module from Microsoft Learn that covers the fundamental concepts and usage of EF Core.

EF Core Migrations Explained(documentation)

Detailed documentation on how to use EF Core Migrations to manage database schema changes effectively.

Querying Data with EF Core(documentation)

Learn how to retrieve data from your database using LINQ queries with Entity Framework Core.

Entity Framework Core: Performance Best Practices(documentation)

Essential guidance on optimizing the performance of your EF Core data access layer.

Integrating EF Core with Azure SQL Database(tutorial)

A practical guide on connecting and using Entity Framework Core with Azure SQL Database.

EF Core: Working with Relationships(documentation)

Understand how to model and manage relationships between entities in EF Core, such as one-to-many and many-to-many.

Entity Framework Core Overview

Entity Framework Core: An Overview

What is an ORM?

An ORM bridges the gap between object-oriented programming and relational databases.

Key Concepts in EF Core

DbContext

DbSet<TEntity>

Entities

Migrations

EF Core and Azure Integration

Common EF Core Operations

Querying Data

Adding Data

Updating Data

Deleting Data

Learning Resources