Immediate.Handlers

Creating handlers

Handlers can be created by using the following code:

        [Handler]
public static partial class GetUsersQuery
{
    public record Query;

    private static ValueTask<IEnumerable<User>> HandleAsync(
        Query _,
        UsersService usersService,
        CancellationToken token
	)
    {
        return usersService.GetUsers();
    }
}

      

This will automatically generate a new class, GetUsersQuery.Handler, which encapsulates the following:

• attaching any behaviors defined for all queries in the assembly
• using a class to receive any DI services, such as UsersService

Any consumer can now do the following:

        public class Consumer(GetUsersQuery.Handler handler)
{
	public async Task Consumer(CancellationToken token)
	{
		var response = await handler.HandleAsync(new(), token);
		// do something with response
	}
}

      

For Command handlers, use a ValueTask, and Immediate.Handlers will insert a return type of ValueTuple to your handler automatically.

        [Handler]
public static partial class CreateUserCommand
{
    public record Command(string Email);

    private static async ValueTask HandleAsync(
        Command command,
        UsersService usersService,
        CancellationToken token
	)
    {
        await usersService.CreateUser(command.Email);
    }
}

      

In case your project layout does not allow direct for references between consumer and handler, the handler will also be registered as an IHandler<TRequest, Response>.

        public class Consumer(IHandler<Query, IEnumerable<User>> handler)
{
	public async Task Consumer(CancellationToken token)
	{
		var response = await handler.HandleAsync(new(), token);
		// do something with response
	}
}

      

# Registering with IServiceCollection

Immediate.Handlers supports Microsoft.Extensions.DependencyInjection.Abstractions directly. To register handlers with DI, simply add the following to your Program.cs:

In your Program.cs, add a call to services.AddXxxHandlers(), where Xxx is the shortened form of the project name.

• For a project named Web, it will be services.AddWebHandlers()
• For a project named Application.Web, it will be services.AddApplicationWebHandlers()

This registers all classes in the assembly marked with [Handler].