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;
  }
}