Building a GraphQL Backend with .NET 6

Introduction

GraphQL has become increasingly popular in recent years thanks to its efficient data querying capabilities and flexibility. With the release of .NET 6, developers now have even more powerful tools to build robust and scalable applications. This guide will take you through the process of creating a GraphQL backend using .NET 6, providing step-by-step procedures along with examples.

Setting Up the Environment

Firstly, ensure you have .NET 6 SDK installed on your machine. You can check the installation by running dotnet --version in your terminal or command prompt.

Next, create a new .NET 6 project using the command line.

dotnet new web -n GraphQLDotNet6Example

This command creates a new web project named "GraphQLDotNet6Example."

Adding Required Packages

To enable GraphQL capabilities in our project, we need to add the necessary packages. Run the following commands in your project directory.

dotnet add package HotChocolate.AspNetCore
dotnet add package HotChocolate.AspNetCore.Playground

These packages provide the essential tools for integrating GraphQL into your .NET 6 application.

Creating GraphQL Schema and Resolvers

Let's define a simple GraphQL schema and corresponding resolvers to demonstrate the functionality. Create a new folder named "GraphQL" and add a file named "Schema.cs" within it.

using HotChocolate;

namespace GraphQLDotNet6Example.GraphQL
{
    public class Query
    {
        public string GetHello() => "Hello, GraphQL in .NET 6!";
    }

    public class QueryType : ObjectType<Query>
    {
        protected override void Configure(IObjectTypeDescriptor<Query> descriptor)
        {
            descriptor.Field(q => q.GetHello()).Type<StringType>().Name("hello");
        }
    }

    public class Schema : GraphQL.Types.Schema
    {
        public Schema(QueryType query)
            : base(new FuncServiceProvider(t => Activator.CreateInstance(t)) 
            {
                {typeof(QueryType), query}
            })
        {
            Query = query;
        }
    }
}

This code snippet creates a simple GraphQL schema with a single query field returning a "Hello" message.

Configuring GraphQL Middleware

In the Startup.cs file, configure the GraphQL middleware.

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using GraphQLDotNet6Example.GraphQL;

namespace GraphQLDotNet6Example
{
    public class Startup
    {
        //...other configurations

        public void ConfigureServices(IServiceCollection services)
        {
            //...other services
            
            services.AddSingleton<Query>();
            services.AddSingleton<QueryType>();
            services.AddSingleton<Schema>(sp =>
                new Schema(sp.GetRequiredService<QueryType>()));

            services.AddGraphQLServer()
                    .AddQueryType<QueryType>()
                    .AddSchema<Schema>();
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            //...other middleware configurations

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapGraphQL();
            });
        }
    }
}

Running the Application

Finally, start your application by running.

dotnet run

Open your browser and navigate to https://localhost:5001/playground to access the GraphQL playground. Here, you can interact with your GraphQL API by writing queries and exploring the schema.

Conclusion

Building APIs with flexible data querying capabilities is an essential part of modern web development. With the help of GraphQL, one can achieve this effectively. If you are interested in building a GraphQL backend using .NET 6, HotChocolate is the way to go. This guide will help you understand the fundamental concepts of setting up a basic GraphQL server in a .NET 6 application.

You can experiment with and expand the capabilities of GraphQL to tailor it to your project's specific requirements. So, get ready to leverage the power of GraphQL and build APIs that meet your needs!