Complex (deeply nested) request validation in ServiceStack, using Fluent Validation

Question

I'm coming up short, trying to use Fluent Validation in the ServiceStack DTOs, when the model have properties nested several levels.

Ex.: The model is structured like this A => B => C => D => E

To validate B without risking a nullref. exception, I need to (successfully) validate A.

To Validate C, A and B must be not null.

D and E have cross dependencies so to validate E then A, B, C AND D must not be null.

The only way that is seemingly available for this scenario, is wrapping the entire thing in when/dependent blocks, but that quickly becomes unmanageable.

Any ideas would be appreciated!

Thanks,

Answer 1

Alternatives of using multiple validators constrained by When() blocks is to either use a "Must" predicate validator, create a Custom Validator or avoid using Fluent Validation for these complex validations and validate them in your Service where you can use full C# to validate them as normal.

Throwing a ArgumentException(message,paramName) in your Service using the name of the Request DTO property will populate the Error in the structured ResponseStatus Errors collection.