Options.FluentValidations 1.0.0-preview

Introduction

Options.FluentValidation adds extension methods on top of Microsoft.Extensions.Options to be able to use FluentValidation for validating your options.

services.AddOptions<TestOption>()
    .Bind(config.GetSection("Options"))
    .ValidateFluently();

How to use

Start by creation your option record:

namespace Options;

public record AppOptions
{
    public const string SectionName = "App";

    public string Name { get; init; }

    public int WorkerCount { get; init; }
}

Create an FluentValidation class:

using FluentValidation;

namespace Options;

public class AppOptionsValidation : AbstractValidator<AppOptions>
{
    public AppOptionsValidation()
    {
        RuleFor(o => o.Name)
            .NotEmpty()
            .NotNull();

        RuleFor(o => o.WorkerCount)
            .GreaterThan(0)
            .LessThan(20);
    }
}

Then add the option to your IServiceCollection by following:

using Options.FluentValidation;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;

namespace Options;

public static class ServiceCollectionExtensions
{
    public static IServiceCollection AddOptions(this IServiceCollection services, IConfiguration config)
    {
        services.AddOptions<AppOptions>()
            .Bind(config.GetRequiredSection(AppOptions.SectionName))
            .ValidateFluently()
            .ValidateOnStart();  // Add Microsoft.Extensions.Hosting package

        return services;
    }
}

Then you can add the configuration to your json file or any other means of setting up your configurations.

{
    "App": {
        "Name": "My fancy app",
        "WorkerCount": 15
    }
}