Separated Fluent Validators

[Hookyns]

Anyone craving a fluent validation style in Validly? The good "old" super-performant, zero-allocation library (Validly) – but with rules in a separate class, where you can ‘happily’ forget to update them after changing your model? 😄

I think I can support something like this:

[Validator<SomeDto>] // [Validator(typeof(SomeDto))]
public partial class SomeDtoValidator
{
	static SomeDtoValidator()
	{
		Name.NotEmpty().MinLength(3).MaxLength(50);
		Age.Between(0, 120);
	}

	private static Validation BeforeValidate(SomeDto obj) // Optional; Adaptible signature like current Validly validation
	{
		return Validation.Success();
	}

	private static void AfterValidate(SomeDto obj) // Optional; Adaptible signature like current Validly validation
	{
	}
}

Validated object:

public class SomeDto
{
	public string Name { get; init; };
	public int Age { get; init; }
}

It would generate something like this:

public partial class SomeDtoValidator : global::Validly.Validators.IInternalValidator
{
	// NEW: Validation rule builders for each property
	private static StringPropertyValidator Name = new();
	private static IntPropertyValidator Age = new();

	// Methods that Validly currently generates here...
}

And also it would generate an extension method, so the usage can be the same. Or would it be okay for you if Validate() method were still generated on the object itself? That would make abstract access (e.g., middleware validation) easier and more performant.

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I haven’t thought it through in full depth, but I believe it should be possible to write it while still keeping compatibility with the current Validly implementation and developer experience.