Mediator

Small .NET library that helps with the implementation of mediator pattern for commands, events and queries.

Using a mediator instance, send commands, broadcast events and fetch queries from their respective generic handlers.

Articles

• Introduction to the mediator pattern in ASP.NET Core applications
• Using Mediator Pipelines in ASP.NET Core Applications
• Validation with Mediator Pipelines in ASP.NET Core Applications
• Transaction Management with Mediator Pipelines in ASP.NET Core
• Auditing with Mediator Pipelines in ASP.NET Core

Installation

The library is available via NuGet packages:

NuGet	Description	Version
SimpleSoft.Mediator.Abstractions	interfaces and abstract implementations (commands, events, queries, mediator, ...)
SimpleSoft.Mediator	core implementation
SimpleSoft.Mediator.Microsoft.Extensions	specialized methods and classes for the Microsoft dependency injection container and logging facades
SimpleSoft.Mediator.Microsoft.Extensions.DatabaseTransactionPipeline	mediator pipeline to enforce SimpleSoft.Database transactions
SimpleSoft.Mediator.Microsoft.Extensions.EFCoreTransactionPipeline	mediator pipeline to enforce Entity Framework Core transactions
SimpleSoft.Mediator.Microsoft.Extensions.LoggingPipeline	pipeline that serializes commands, queries, events and results into the logging
SimpleSoft.Mediator.Microsoft.Extensions.ValidationPipeline	pipeline that enforces validation into commands, queries and events before entering the handlers by using FluentValidation

Package Manager

Install-Package SimpleSoft.Mediator.Abstractions
Install-Package SimpleSoft.Mediator
Install-Package SimpleSoft.Mediator.Microsoft.Extensions
Install-Package SimpleSoft.Mediator.Microsoft.Extensions.DatabaseTransactionPipeline
Install-Package SimpleSoft.Mediator.Microsoft.Extensions.EFCoreTransactionPipeline
Install-Package SimpleSoft.Mediator.Microsoft.Extensions.LoggingPipeline
Install-Package SimpleSoft.Mediator.Microsoft.Extensions.ValidationPipeline

.NET CLI

dotnet add package SimpleSoft.Mediator.Abstractions
dotnet add package SimpleSoft.Mediator
dotnet add package SimpleSoft.Mediator.Microsoft.Extensions
dotnet add package SimpleSoft.Mediator.Microsoft.Extensions.DatabaseTransactionPipeline
dotnet add package SimpleSoft.Mediator.Microsoft.Extensions.EFCoreTransactionPipeline
dotnet add package SimpleSoft.Mediator.Microsoft.Extensions.LoggingPipeline
dotnet add package SimpleSoft.Mediator.Microsoft.Extensions.ValidationPipeline

Compatibility

This library is compatible with the following frameworks:

• SimpleSoft.Mediator.Abstractions
  • .NET Framework 4.0+;
  • .NET Standard 1.0+;
• SimpleSoft.Mediator
  • .NET Framework 4.0+;
  • .NET Standard 1.0+;
• SimpleSoft.Mediator.Microsoft.Extensions
  • .NET Standard 1.1+;
• SimpleSoft.Mediator.Microsoft.Extensions.DatabaseTransactionPipeline
  • .NET Standard 1.1+;
• SimpleSoft.Mediator.Microsoft.Extensions.EFCoreTransactionPipeline
  • .NET Standard 1.3+;
• SimpleSoft.Mediator.Microsoft.Extensions.LoggingPipeline
  • .NET Standard 1.1+;
• SimpleSoft.Mediator.Microsoft.Extensions.ValidationPipeline
  • .NET Standard 1.1+;

Usage

Documentation is available via wiki or you can check the working examples or test code.

Here is an example of a command handler that also sends some events:

public class CreateUserCommand : Command {
  public string Email { get; set; }
  public string Password { get; set; }
}

public class UserCreatedEvent : Event {
  public User User { get; set; }
}

public class UserByIdQuery : Query<User> {
  public Guid UserId { get; set; }
}

public class User {
  public Guid Id { get; set; }
  public string Email { get; set; }
}

public class ExampleHandlers : ICommandHandler<CreateUserCommand>, IQueryHandler<UserByIdQuery,User> {
  
  private readonly IMediator _mediator;
  
  public UsersService(IMediator mediator) {
    _mediator = mediator;
  }
  
  public async Task HandleAsync(CreateUserCommand cmd, CancellationToken ct) {
    var userId = Guid.NewGuid();
    
    // try add the user to some store
    
    await _mediator.BroadcastAsync(new UserCreatedEvent {
      User = new User {
        Id = userId,
        Email = cmd.Email
      }
    }, ct);
  }
  
  public async Task<User> HandleAsync(UserByIdQuery query, CancellationToken ct) {
    User user = null;
    
    // search the store by user id
    
    return user;
  }
}