Question

I am trying to develop a fluent valiation rule where if my TitleId FK property is null, then the TitleOther text field becomes mandatory. I have tried several combinations and orders of fluent expressions, all to no avail.

This is what I have so far, if someone can please help me get this one When part correct, I would be most grateful, and a little more educated.

context.RulesFor(p => p.TitleId).Required(p => p.Message("Title is required."));
context.RulesFor(p => p.TitleOther)
        .Required(p => p.Message("Please provide your other title."))
        .Length(0, 50, c => c.Message("Other title may not exceed 50 characters")
        .When(p => context.RulesFor(p => p.TitleId). *[what here?]*

Answer 1

I haven’t used FluentValidation much, but from what I understand from the docs you would need to do

.When(p => p.TitleId == null)

instead of .When(p => context.RulesFor(p => p.TitleId). *[what here?]*