New Post: NullReferenceException using FluentValidation in MVC3

Got it - thanks.

Looking at this, it appears the issue was fixed last month in a patch, however I haven't yet got round to doing a new deployment since then. If you download and build from source, then the error should go away.

As expected, the problem was caused by using RuleFor(t => t). Doing this is not supported (with FluentValidation, rules should be defined against properties, not against the object itself). However, although this isn't supported it shouldn't cause a crash. Someone noticed this issue last month and kindly provided a patch for it.

With the TestIsDefined rule, I'd recommend associating it with one of the properties, eg TestID:

public TestValidator()
{
    RuleFor(t => t.TestID).Must(TestIsDefined).WithMessage("User must select existing customer or provide at least a new customer name");
}privatebool TestIsDefined(TestModel model, int? testId)
{return (TestID.HasValue || (string.IsNullOrWhiteSpace(model.TestName) && string.IsNullOrWhiteSpace(model.TestDescription)));
}

However, if you really want to use RuleFor(t=>t) then you'll need to call .OverridePropertyName as part of the rule (as FV won't be able to automatically determine which property to associate the rule with).

Jeremy