AbstractValidator for Anonymous Type

Question

internal sealed class MeetingValidator : AbstractValidator<Meeting> 
{
    public MeetingValidator()
    {
      RuleFor(m => new { m.Start, m.End })
        .Must(d => d.End - d.Start > 0)

      // Other Rules
    }
}

Is there a way to declare a AbstractValidator on an anonymous type ?

This is for refactoring purposes.

The test is common to other types than Meeting and I want to minimize the duplication of my code.

internal sealed class EndDateValidator : AbstractValidator<????> 
{
    public EndDateValidator ()
    {
      RuleFor(m => ????)
        .Must(d => d.End - d.Start > 0)
    }
}


public static IRuleBuilderOptions<T, ????> MustHaveAEndStartDate<T>(this IRuleBuilder<T,  ????> ruleBuilder)
{
    return ruleBuilder.SetValidator(new EndDateValidator());
}


internal sealed class MeetingValidator : AbstractValidator<Meeting> 
{
    public MeetingValidator()
    {
      RuleFor(m => new { m.Start, m.End }) // or something else
        .MustHaveValidEndDate()
    }
}

Answer 1

In case you can't refactor the source class(es) (here: Meeting), then you can use a (DateTime Start, DateTime End) ValueTuple instead of an anonymous type, defining the validator as inheriting from AbstractValidator<(DateTime Start, DateTime End)>.

internal sealed class MeetingValidator : AbstractValidator<Meeting>
{
    public MeetingValidator()
    {
        RuleFor<(DateTime, DateTime)>(o => new(o.Start, o.End))
            .MustHaveValidEndDate();
    }
}

internal sealed class EndDateValidator : AbstractValidator<(DateTime Start, DateTime End)>
{
    public EndDateValidator()
    {
        RuleFor(o => o).Must(o => o.End > o.Start);
    }
}

public static class Extensions
{
    public static IRuleBuilderOptions<T, (DateTime Start, DateTime End)> MustHaveValidEndDate<T>(
        this IRuleBuilder<T, (DateTime Start, DateTime End)> ruleBuilder
        )
    {
        return ruleBuilder.SetValidator(new EndDateValidator());
    }
}