Concordia.Generator 1.0.1

Concordia.Generator: Compile-Time Handler Registration for Concordia

Concordia.Generator is the C# Source Generator component of the Concordia library. It automates the registration of your request handlers, notification handlers, pre-processors, post-processors, and pipeline behaviors at compile-time, eliminating the need for runtime reflection and significantly improving application startup performance.

Why Concordia?

• An Open-Source Alternative: Concordia was created as an open-source alternative in response to other popular mediator libraries (like MediatR) transitioning to a paid licensing model. We believe core architectural patterns should remain freely accessible to the developer community.
• Lightweight and Minimal: Provides only the essential Mediator pattern functionalities, without unnecessary overhead.
• Optimized Performance: Thanks to Source Generators, handler discovery and registration happen entirely at compile-time, ensuring faster application startup and zero runtime reflection.
• Easy DI Integration: Integrates seamlessly with Microsoft.Extensions.DependencyInjection.
• Same MediatR Interfaces: Uses interfaces with identical signatures to MediatR, making migration or parallel adoption extremely straightforward.
• CQRS and Pub/Sub Patterns: Facilitates the implementation of Command Query Responsibility Segregation (CQRS) and Publisher/Subscriber principles, enhancing separation of concern and code maintainability.

Key Features

• Automatic Handler Registration: Scans your assemblies at compile-time to find and register IRequestHandler, INotificationHandler, IPipelineBehavior, IRequestPreProcessor, and IRequestPostProcessor implementations.
• Zero Runtime Reflection: All service registration code is generated as C# source files, which are then compiled directly into your assembly.
• Configurable Namespace and Method Names: Control the generated class's namespace and the DI extension method's name via MSBuild properties in your .csproj file.

Installation

Install Concordia.Core and Concordia.Generator in your application project:

dotnet add package Concordia.Core --version 1.0.0
dotnet add package Concordia.Generator --version 1.0.0

Usage

1. Define your Handlers, Processors, and Behaviors (as described in Concordia.Core's documentation).

2. Configure your .csproj: Add the Concordia.Generator as a ProjectReference with specific attributes and optionally configure the generated method name and namespace.

   <Project Sdk="Microsoft.NET.Sdk.Web">
     <PropertyGroup>
       <TargetFramework>net8.0</TargetFramework>
       <Nullable>enable</Nullable>
       <ImplicitUsings>enable</ImplicitUsings>
   
       <ConcordiaGeneratedMethodName>AddMyCustomMediatorHandlers</ConcordiaGeneratedMethodName>
   
   
     </PropertyGroup>
   
     <ItemGroup>
       <ProjectReference Include="PathToYour\Concordia.Core\Concordia.Core.csproj" />
       <ProjectReference Include="PathToYour\Concordia.Generator\Concordia.Generator.csproj"
                         OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
     </ItemGroup>
   </Project>
   

3. Register services in Program.cs:

   using Concordia; // Required for IMediator, ISender
   using Concordia.DependencyInjection; // For AddConcordiaCoreServices
   using MyProject.Web; // Example: Namespace where ConcordiaGeneratedRegistrations is generated
   
   var builder = WebApplication.CreateBuilder(args);
   
   // 1. Register Concordia's core services.
   builder.Services.AddConcordiaCoreServices();
   
   // 2. Register your specific handlers and pipeline behaviors discovered by the generator.
   // The method name will depend on your .csproj configuration (e.g., AddMyCustomMediatorHandlers).
   builder.Services.AddMyCustomMediatorHandlers(); // Use the name configured in .csproj
   
   builder.Services.AddControllers();
   var app = builder.Build();
   app.MapControllers();
   app.Run();
   

The Source Generator will automatically find your handler implementations and generate a static class (e.g., ConcordiaGeneratedRegistrations) containing an extension method (e.g., AddMyCustomMediatorHandlers) that registers all your services with the DI container.

Contribution

Feel free to contribute to the project! Report bugs, suggest new features, or submit pull requests.

License

This project is released under the [Insert your license here, e.g., MIT License].