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RESTful APIs are widely used for data exchange between web applications and mobile applications. ASP.NET Core is an ideal framework for creating RESTful APIs on the .NET platform. In this article, we will explore the fundamentals of building RESTful APIs with ASP.NET Core and discuss advanced techniques to make your APIs more robust and scalable.
Scope of the Article
This article will cover the following topics:
- Definitions: API, RESTful API, ASP.NET Core, ORM, Entity Framework Core, database, layered architecture, design pattern, Repository pattern, Unit of Work pattern
- Creating a New API Project with ASP.NET Core: Setting up a new ASP.NET Core API project using Visual Studio and basic configuration
- Creating a Database Model with Entity Framework Core: Defining objects representing database tables and relationships, and interacting with the database using Entity Framework Core
- Design Patterns and Layered Architecture: Using design patterns like Repository and Unit of Work to make your API more modular and maintainable, and dividing the API into different layers
- Creating RESTful APIs for CRUD Operations: Using HTTP methods like GET, POST, PUT, DELETE to create RESTful APIs for CRUD (Create, Read, Update, Delete) operations
- Securing the API: Protecting your API from unauthorized access using authentication and authorization mechanisms like JWT tokens
- Creating API Documentation with Swagger: Generating clear and interactive documentation for your API using Swagger
- Testing the API: Ensuring the functionality and reliability of your API through unit tests and end-to-end tests
Differences of This Article
This article differs from other API development articles in the following ways:
- Comprehensive: Covers both the basics and advanced techniques of API development.
- Practical: Includes example codes and step-by-step guides to reinforce the information provided.
- Up-to-date: Updated according to the latest version of ASP.NET Core and current web development trends.
Target Audience
This article is intended for the following individuals:
- Those who want to start developing RESTful APIs with ASP.NET Core
- Those who want to improve their API development skills
- Those who want to create more robust and scalable APIs
Nowadays, RESTful APIs are widely used for data exchange between web applications and mobile applications. ASP.NET Core is an ideal framework for creating RESTful APIs on the .NET platform. In this article, we will explore the fundamentals of building RESTful APIs with ASP.NET Core.
Part 1: Definitions
API (Application Programming Interface): An interface used to communicate between two or more software systems. APIs open up the functions of one system to other systems, allowing data exchange and functionality sharing.
RESTful API (Representational State Transfer API): A type of API that uses the REST architecture. REST is an architectural style for web services based on six principles:
- Defined resources: Each resource is identified by a URI (Uniform Resource Identifier).
- Uniform interface: All operations are performed using HTTP methods (GET, POST, PUT, DELETE).
- Statelessness: Each request is processed independently of previous requests.
- Caching: Data can be cached by intermediaries and clients.
- Layering: The system can be divided into layers.
- Code on demand: The server does not send application code to the client.
ASP.NET Core: An open-source, cross-platform web development framework developed by Microsoft. ASP.NET Core enables the development of websites, web APIs, mobile applications, and IoT (Internet of Things) devices.
ORM (Object-Relational Mapping): Maps objects to database tables and queries, simplifying database operations. By using ORM, you can interact with the database through objects without writing SQL queries.
Entity Framework Core: An open-source ORM framework developed by Microsoft. Entity Framework Core is used to simplify database interactions on the .NET platform.
Design Pattern: We can use design patterns like Repository Pattern and Unit of Work Pattern for the design and development of our API. The Repository pattern abstracts the database interaction, making database access easier. The Unit of Work pattern treats multiple database operations as a single transaction, ensuring consistency.
- Design Pattern Features:
- Solves recurring problems. Provides general solutions to common software problems.
- Increases code reusability. Provides reusable code segments for different projects.
- Makes code more organized and understandable.
- Makes code easier to test.
- Makes code easier to scale.
- Common Design Patterns:
- Repository Pattern
- Unit of Work Pattern
- Factory Pattern
- Singleton Pattern
- Strategy Pattern
Part 2: Creating a New API Project with ASP.NET Core
The first step in creating a RESTful API with ASP.NET Core is to create a new project. We will use Visual Studio to create a new ASP.NET Core Web API project.
- Step 1: Open Visual Studio and select “Create a new project”.
- Step 2: Select “ASP.NET Core Web API” and click “Next”.
- Step 3: Enter a name for your project and click “Create”.
- Step 4: Select the .NET Core version you want to use and click “Create”
- Step 5: Your new ASP.NET Core Web API project will be created.
Setting Up the Project
After creating the project, you need to configure the project settings:
- Step 1: Open the Startup.cs file and configure the services and middleware.
- Step 2: Add the necessary packages to the project.
- Microsoft.EntityFrameworkCore
- Microsoft.EntityFrameworkCore.SqlServer
- Microsoft.EntityFrameworkCore.Tools
Part 3: Creating a Database Model with Entity Framework Core
The next step is to create the database model. We will use Entity Framework Core to define the database tables and relationships. We will also create a context class to interact with the database.
- Step 1: Create a new folder named “Models” and add a new class named “Product.cs”.
- Step 2: Define the properties of the Product class.
public class Product
{
public int Id { get; set; }
public string Name { get; set; }
public decimal Price { get; set; }
public int Stock { get; set; }
}
- Step 3: Create a new class named “ApplicationDbContext.cs” in the “Data” folder and inherit from DbContext.
public class ApplicationDbContext : DbContext
{
public ApplicationDbContext(DbContextOptions options)
: base(options)
{
}
public DbSet Products { get; set; }
}
- Step 4: Configure the database connection in the appsettings.json file.
{
"ConnectionStrings": {
"DefaultConnection": "Server=(localdb)\\mssqllocaldb;Database=MyDatabase;Trusted_Connection=True;MultipleActiveResultSets=true"
}
}
- Step 5: Configure the DbContext in the Startup.cs file.
public void ConfigureServices(IServiceCollection services)
{
services.AddDbContext(options =>
options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
}
Part 4: Design Patterns and Layered Architecture
Using design patterns like Repository and Unit of Work makes your API more modular and maintainable. The Repository pattern abstracts the database interaction, making it easier to switch between different data sources. The Unit of Work pattern groups multiple operations into a single transaction, ensuring data consistency.
Repository Pattern
The Repository pattern abstracts the database interaction, making it easier to switch between different data sources. To implement the Repository pattern, create a new folder named “Repositories” and add an interface named “IRepository.cs”.
public interface IRepository where T : class
{
Task<IEnumerable> GetAllAsync();
Task GetByIdAsync(int id);
Task AddAsync(T entity);
Task UpdateAsync(T entity);
Task DeleteAsync(int id);
}
- Step 1: Create a new class named “Repository.cs” that implements the IRepository interface.
public class Repository : IRepository where T : class
{
private readonly ApplicationDbContext _context;
public Repository(ApplicationDbContext context)
{
_context = context;
}
public async Task<IEnumerable> GetAllAsync()
{
return await _context.Set().ToListAsync();
}
public async Task GetByIdAsync(int id)
{
return await _context.Set().FindAsync(id);
}
public async Task AddAsync(T entity)
{
await _context.Set().AddAsync(entity);
await _context.SaveChangesAsync();
}
public async Task UpdateAsync(T entity)
{
_context.Set().Update(entity);
await _context.SaveChangesAsync();
}
public async Task DeleteAsync(int id)
{
var entity = await _context.Set().FindAsync(id);
_context.Set().Remove(entity);
await _context.SaveChangesAsync();
}
}
- Step 2: Register the repository in the Startup.cs file.
public void ConfigureServices(IServiceCollection services)
{
services.AddScoped(typeof(IRepository<>), typeof(Repository<>));
}
Unit of Work Pattern
The Unit of Work pattern groups multiple operations into a single transaction, ensuring data consistency. To implement the Unit of Work pattern, create a new interface named “IUnitOfWork.cs”.
public interface IUnitOfWork : IDisposable
{
IRepository Products { get; }
Task CompleteAsync();
}
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