MessageValidation.FluentValidation 0.3.0

MessageValidation.FluentValidation

FluentValidation adapter for the MessageValidation pipeline — automatically bridge your existing FluentValidation validators into the protocol-agnostic message validation pipeline.

Installation

dotnet add package MessageValidation.FluentValidation

Quick Start

1. Define your message

public class TemperatureReading
{
    public string SensorId { get; set; } = "";
    public double Value { get; set; }
    public DateTime Timestamp { get; set; }
}

2. Create a FluentValidation validator

Write a standard FluentValidation AbstractValidator<T> — no special base class required:

using FluentValidation;

public class TemperatureReadingValidator : AbstractValidator<TemperatureReading>
{
    public TemperatureReadingValidator()
    {
        RuleFor(x => x.SensorId).NotEmpty();
        RuleFor(x => x.Value).InclusiveBetween(-50, 150);
        RuleFor(x => x.Timestamp).LessThanOrEqualTo(DateTime.UtcNow);
    }
}

3. Register services

using MessageValidation;
using MessageValidation.FluentValidation;

builder.Services.AddMessageValidation(options =>
{
    options.MapSource<TemperatureReading>("sensors/+/temperature");
    options.DefaultFailureBehavior = FailureBehavior.Log;
});

// Scan the assembly for all AbstractValidator<T> implementations
// and register the FluentValidation adapter as the IMessageValidator<T> bridge.
builder.Services.AddMessageFluentValidation(typeof(Program).Assembly);

builder.Services.AddMessageDeserializer<JsonMessageDeserializer>();
builder.Services.AddMessageHandler<TemperatureReading, TemperatureHandler>();

That's it. The pipeline will now use your TemperatureReadingValidator automatically when a TemperatureReading message arrives.

How It Works

AddMessageFluentValidation does two things:

1. Scans assemblies for all AbstractValidator<T> implementations and registers them in the DI container (via FluentValidation.DependencyInjectionExtensions).
2. Registers an open-generic adapter (FluentValidationMessageValidator<T>) that implements IMessageValidator<T> by delegating to FluentValidation's IValidator<T>.

IMessageValidator<T>
    └── FluentValidationMessageValidator<T>
            └── IValidator<T>  (your AbstractValidator<T>)

API Reference

AddMessageFluentValidation(params Assembly[] assemblies)

// Scan specific assemblies
builder.Services.AddMessageFluentValidation(
    typeof(TemperatureReadingValidator).Assembly,
    typeof(DeviceHeartbeatValidator).Assembly);

// Or scan the calling assembly (default)
builder.Services.AddMessageFluentValidation();

Requirements

• .NET 10+
• MessageValidation core package
• FluentValidation 11+

License

MIT