ClearFeatureActions 1.2.0

ClearFeatureActions

Description

ClearFeatureActions is a robust framework designed to encapsulate a request and its process flow within a feature. Each action serves as a subset of a specific feature, consisting of three main components: a request, a handler, and a validator. The feature action coordinates these components to ensure seamless functionality.

• The handler is responsible for executing the requests.
• The validator ensures that all validation checks are completed before any execution is attempted.

This approach guarantees that the workflow is robust and efficient. The project relies on FluentValidation for validation logic and FluentResults for managing execution results.

Features

• Encapsulation of request and process flow
• Robust validation using FluentValidation
• Efficient result management using FluentResults
• Notification system with support for multiple handlers
• Concurrent and sequential execution modes for notification handlers
• Publisher-subscriber pattern implementation

Installation

To install ClearFeatureActions, add the following package references to your project file:

<PackageReference Include="ClearFeatureActions" Version="1.2.0" />

Usage

Feature Actions

1. Define a request by implementing the IRequest<TResponse> interface.
2. Implement a handler for the request by implementing the IRequestHandler<TRequest, TResponse> interface.
3. Optionally, implement a validator for the request by inheriting from AbstractValidator<TRequest>.
4. Register the feature actions in your service collection using the AddFeatureActions extension method.

Notifications

1. Define a notification by implementing the INotification interface.
2. Implement one or more handlers for the notification by implementing the INotificationHandler<TNotification> interface.
3. Register the notification publishers in your service collection using the AddNotificationPublishers extension method.
4. Inject and use INotificationPublisher<TNotification> to publish notifications.

Examples

Feature Action Example

Here's an example of how to use the feature action framework with a sample request, handler, and execution in a dependency-injected service.

Step 1: Define the Request

A request to check if a user exists by their ID, returning a bool.

public class CheckUserExistsRequest : IRequest<bool>
{
    public int UserId { get; }

    public CheckUserExistsRequest(int userId)
    {
        UserId = userId;
    }
}

Step 2: Implement the Request Handler

Handles the request using a user repository.

public class CheckUserExistsHandler : IRequestHandler<CheckUserExistsRequest, bool>
{
    private readonly IUserRepository _userRepository;

    public CheckUserExistsHandler(IUserRepository userRepository)
    {
        _userRepository = userRepository;
    }

    public async Task<Result<bool>> Handle(CheckUserExistsRequest request, CancellationToken cancellationToken)
    {
        var exists = await _userRepository.ExistsAsync(request.UserId);
        return Result.Ok(exists);
    }
}

Step 3: Optional Validator

Ensures the UserId is valid.

public class CheckUserExistsValidator : AbstractValidator<CheckUserExistsRequest>
{
    public CheckUserExistsValidator()
    {
        RuleFor(x => x.UserId).GreaterThan(0).WithMessage("User ID must be greater than zero.");
    }
}

Step 4: Register Dependencies Using AddFeatureActions

Automatically register all feature actions, handlers, and validators in Program.cs or Startup.cs:

var assembly = Assembly.GetExecutingAssembly(); // Get the current assembly
services.AddFeatureActions(assembly); // Auto-registers everything in DI

Step 5: Use the Feature Action in a Controller

Inject IFeatureAction<CheckUserExistsRequest, bool> into a controller and expose an API endpoint.

[ApiController]
[Route("api/users")]
public class UsersController : ControllerBase
{
    private readonly IFeatureAction<CheckUserExistsRequest, bool> _checkUserExistsAction;

    public UsersController(IFeatureAction<CheckUserExistsRequest, bool> checkUserExistsAction)
    {
        _checkUserExistsAction = checkUserExistsAction;
    }

    [HttpGet("{userId}/exists")]
    public async Task<IActionResult> CheckUserExists(int userId, CancellationToken cancellationToken)
    {
        var result = await _checkUserExistsAction.Execute(new CheckUserExistsRequest(userId), cancellationToken);

        if (!result.IsSuccess)
            return BadRequest(result.Errors); // Return validation errors if any

        return Ok(new { Exists = result.Value });
    }
}

Notification Example

Here's an example of how to use the notification system to handle events across multiple handlers.

Step 1: Define the Notification

A notification for when a user is created.

public class UserCreatedNotification : INotification
{
    public int UserId { get; }
    public string Email { get; }
    public DateTime CreatedAt { get; }

    public UserCreatedNotification(int userId, string email, DateTime createdAt)
    {
        UserId = userId;
        Email = email;
        CreatedAt = createdAt;
    }
}

Step 2: Implement Notification Handlers

Create multiple handlers that respond to the notification.

// Handler for sending welcome email (supports concurrent execution)
public class SendWelcomeEmailHandler : INotificationHandler<UserCreatedNotification>
{
    private readonly IEmailService _emailService;

    public bool SupportsConcurrentExecution => true; // Can run concurrently

    public SendWelcomeEmailHandler(IEmailService emailService)
    {
        _emailService = emailService;
    }

    public async Task Handle(UserCreatedNotification notification, CancellationToken cancellationToken)
    {
        await _emailService.SendWelcomeEmailAsync(notification.Email, cancellationToken);
    }
}

// Handler for logging user creation (requires sequential execution)
public class LogUserCreationHandler : INotificationHandler<UserCreatedNotification>
{
    private readonly ILogger _logger;

    public bool SupportsConcurrentExecution => false; // Must run sequentially

    public LogUserCreationHandler(ILogger logger)
    {
        _logger = logger;
    }

    public async Task Handle(UserCreatedNotification notification, CancellationToken cancellationToken)
    {
        _logger.LogInformation($"User {notification.UserId} created at {notification.CreatedAt}");
        await Task.CompletedTask;
    }
}

Step 3: Register Notification Publishers

Register the notification system in your service collection:

var assembly = Assembly.GetExecutingAssembly();
services.AddNotificationPublishers(assembly); // Auto-registers notification publishers and handlers

Step 4: Publish Notifications

Use the notification publisher in your service to broadcast events:

public class UserService
{
    private readonly INotificationPublisher<UserCreatedNotification> _notificationPublisher;
    private readonly IUserRepository _userRepository;

    public UserService(
        INotificationPublisher<UserCreatedNotification> notificationPublisher,
        IUserRepository userRepository)
    {
        _notificationPublisher = notificationPublisher;
        _userRepository = userRepository;
    }

    public async Task<User> CreateUserAsync(string email, CancellationToken cancellationToken)
    {
        var user = await _userRepository.CreateAsync(email, cancellationToken);
        
        // Publish notification to all registered handlers
        var notification = new UserCreatedNotification(user.Id, user.Email, user.CreatedAt);
        await _notificationPublisher.Publish(notification, cancellationToken);
        
        return user;
    }
}

Key Benefits

Feature Actions

• Separation of Concerns: Clear separation between request definition, handling logic, and validation
• Dependency Injection: Automatic registration and resolution of handlers and validators
• Result Management: Built-in error handling with FluentResults
• Validation: Integrated FluentValidation support

Notifications

• Decoupled Architecture: Publishers don't need to know about specific handlers
• Multiple Handlers: Support for multiple handlers per notification type
• Execution Control: Choose between concurrent and sequential execution per handler
• Scalability: Easy to add new handlers without modifying existing code

License

This project is licensed under the MIT License. See the LICENSE file for details.