.NET GraphQL APIs with HotChocolate

Effortlessly create modern, scalable, and efficient GraphQL APIs with HotChocolate in .NET.

Table of Contents

• Introduction
• What is GraphQL?
• Why Choose HotChocolate?
• Setting Up HotChocolate in .NET
• Implementing GraphQL with HotChocolate
• GraphQL Query Examples
• Best Practices for GraphQL APIs
• Conclusion

Introduction

With the rise of modern APIs, GraphQL has become a popular alternative to REST, offering flexible and efficient data querying. HotChocolate is a powerful .NET library for building GraphQL APIs. In this blog, we will explore the basics of GraphQL, the features of HotChocolate, and how to implement scalable GraphQL APIs using .NET.

What is GraphQL?

GraphQL is a query language for APIs, developed by Facebook, that provides a more efficient, flexible, and powerful alternative to REST. Instead of fetching fixed endpoints, clients can specify the exact data structure they need.

• Single Endpoint: Unlike REST, GraphQL uses a single endpoint for all operations.
• Client-Defined Queries: The client defines the structure of the response.
• Real-Time Data: Enables real-time updates using subscriptions.

Why Choose HotChocolate?

HotChocolate is an open-source library that simplifies the creation of GraphQL APIs in .NET. Here’s why it stands out:

• Code-First Approach: Allows defining GraphQL schemas directly in C#.
• Advanced Tooling: Built-in features like filtering, sorting, and projections.
• Subscription Support: Out-of-the-box support for real-time data.
• Integration: Seamless integration with ASP.NET Core middleware.
• Performance: Optimized for high-performance APIs.

Setting Up HotChocolate in .NET

Step 1: Install HotChocolate NuGet Packages

Use the following commands to install the required NuGet packages:

dotnet add package HotChocolate.AspNetCore

dotnet add package HotChocolate.Data

Step 2: Configure Services

Add HotChocolate to your service container in Program.cs:

builder.Services
    .AddGraphQLServer()
    .AddQueryType<Query>();
            

Step 3: Add Middleware

Configure the middleware in your app pipeline:

app.MapGraphQL();
            

Implementing GraphQL with HotChocolate

Step 1: Define a Query Type

public class Query
{
    public string HelloWorld() => "Hello, GraphQL!";
}
            

Step 2: Add a Data Model

public class Book
{
    public int Id { get; set; }
    public string Title { get; set; }
    public string Author { get; set; }
}
            

Step 3: Create a Resolver

public class Query
{
    public IEnumerable<Book> GetBooks() => new List<Book>
    {
        new Book { Id = 1, Title = "C# in Depth", Author = "Jon Skeet" },
        new Book { Id = 2, Title = "Pro ASP.NET Core", Author = "Adam Freeman" }
    };
}
            

GraphQL Query Examples

Use the following queries in GraphQL Playground to fetch data:

Query Example

query {
    books {
        id
        title
        author
    }
}
            

Best Practices for GraphQL APIs

• Use versioning strategies to manage breaking changes.
• Implement proper authentication and authorization mechanisms.
• Leverage HotChocolate’s built-in features like filtering and sorting.
• Use caching for frequently accessed data.
• Monitor API performance using tools like App Insights.

Conclusion

HotChocolate makes building GraphQL APIs in .NET a seamless experience. Its code-first approach, advanced features, and integration with ASP.NET Core allow developers to create modern, scalable APIs. By following the steps and best practices in this blog, you can start building GraphQL APIs for your applications today.

© 2025 Sandeep Mhaske | Ayodhyya