hotchoc graphql with database services

To setup graphql backend that lookup database records, you can use  hotchoc's ServiceAttribute, as shown in the code snippet here:

using System.Collections.Generic;

using HotChocolate;

using HotChocolate.Types;

using HotChocolate.Types.Relay;

namespace Accounts.Types

{

    [QueryType]

    public class Query

    {        

        public IEnumerable<User> GetUsers([Service] UserRepository repository) =>

            repository.GetUsers();

        [NodeResolver]

        public User GetUser(int id, [Service] UserRepository repository) =>

            repository.GetUser(id);

    }

}

You can add database customization code later, for a demo example, a UserRepository would look like this. 

public class UserRepository

    {

        private readonly Dictionary<int, User> _users;

        public UserRepository()

        {

            _users = new User[]

            {

                new User(1, "Ada Lovelace", new DateTime(1815, 12, 10), "@ada"),

                new User(2, "Alan Turing", new DateTime(1912, 06, 23), "@complete")

            }.ToDictionary(t => t.Id);

        }

        public User GetUser(int id) => _users[id];

        public IEnumerable<User> GetUsers() => _users.Values;

    }

To wire it all up, you can do the following in Program.cs.

using Microsoft.AspNetCore.Builder;

using Microsoft.Extensions.Hosting;

using Microsoft.Extensions.DependencyInjection;

using Accounts.Types;

var builder = WebApplication.CreateBuilder(args);

builder.Services

    .AddSingleton<UserRepository>();

builder.Services

    .AddGraphQLServer()

    .AddTypes()

    .AddGlobalObjectIdentification()

    .RegisterService<UserRepository>();

var app = builder.Build();

app.MapGraphQL();

app.RunWithGraphQLCommands(args);

For a complete code example, please check out

https://github.com/mitzenjeremywoo/hotchoc-federation-centralize.git