OpenMediator

Alternative for those who do not want to pay for a mediator implementation.

Configuration

In your Program.cs call AddOpenMediator

services.AddOpenMediator(config =>
{
    config.RegisterCommandsFromAssemblies([Assembly.GetExecutingAssembly()]);
});

Usage

1 Create commands

public record CreateUserCommand(int Id, string Name) : ICommand;

2 Call MediatorBus

[ApiController]
[Route("api/user")]
public class UserController(IMediatorBus _mediator) : ControllerBase
{
    [HttpPost()]
    public async Task<IActionResult> CreateUser()
    {
        var command = new CreateUserCommand(1, "UserTest");
        await _mediator.SendAsync(command);

        return Ok();
    }
}

3 Define your use case

public record CreateUserCommandHandler(ILogger<CreateUserCommandHandler> _logger) : ICommandHandler<CreateUserCommand>
{
    public async Task HandleAsync(CreateUserCommand command)
    {
        // Simulate some work
        await Task.Delay(1000);
    }
}

Middleware Configuration

Also you can configure and execute custom middlewares before or after the command.

1. Define your middleware by implementing the IMediatorMiddleware interface:

public class CustomMediatorMiddleware() : IMediatorMiddleware
{
    public async Task ExecuteAsync<TCommand>(TCommand command, Func<Task> next)
        where TCommand : ICommand
    {
        // Do something before the command
        await Task.Delay(500);

        await next();

        // Do something after the command
        await Task.Delay(500);
    }

    public async Task<TResponse> ExecuteAsync<TCommand, TResponse>(TCommand command, Func<Task<TResponse>> next)
        where TCommand : ICommand<TResponse>
    {
        // Do something before the command
        await Task.Delay(500);

        var result = await next();

        // Do something after the command
        await Task.Delay(500);

        return result;
    }
}

2. Register your middlewares in the AddOpenMediator method:

services.AddOpenMediator(config =>
{
    config.RegisterCommandsFromAssemblies([Assembly.GetExecutingAssembly()]);
    config.RegisterMiddleware<CustomMediatorMiddleware>();
});