Stop Fluent Validation on first failure

Question

i'm defining a validation for my Request objects. I would like the validator to stop on the very first failure, not only the one on the same chain. In the example below, if my TechnicalHeader object is null, i get a NullReference exception when the validation reaches the rule for TechnicalHeader.MCUserid.

In poor words, i would like to do a conditional validation over the last three rules in the code below, according to the result of the first rule

using System; using ServiceStack.FluentValidation; using MyProj.Services.Models;  namespace MyProj.Services.BaseService.Validators {     public class BaseValidator<T> : AbstractValidator<T>         where T : RequestBase     {         public BaseValidator()         {             RuleSet(ServiceStack.ApplyTo.Put | ServiceStack.ApplyTo.Post,                  () =>                 {                     this.CascadeMode = CascadeMode.StopOnFirstFailure;                     RuleFor(x => x.TechnicalHeader).Cascade(CascadeMode.StopOnFirstFailure).NotNull().WithMessage("Header cannot be null");                     RuleFor(x => x.TechnicalHeader).NotEmpty().WithMessage("Header cannot be null");                     RuleFor(x => x.TechnicalHeader.Userid).NotEmpty().WithMessage("Userid cannot be null or an empty string");                     RuleFor(x => x.TechnicalHeader.CabCode).GreaterThan(0).WithMessage("CabCode cannot be or less than 0");                     RuleFor(x => x.TechnicalHeader.Ndg).NotEmpty().WithMessage("Ndg cannot be null or an empty string");                 }             );         }     } } 

Answer 1

Just check for null before running the rules that depend on them, using a When condition.

this.CascadeMode = CascadeMode.StopOnFirstFailure; RuleFor(x => x.TechnicalHeader).NotNull().WithMessage("Header cannot be null");  // Ensure TechnicalHeader is provided When(x => x.TechnicalHeader != null, () => {     RuleFor(x => x.TechnicalHeader.Userid).NotEmpty().WithMessage("Userid cannot be null or an empty string");     RuleFor(x => x.TechnicalHeader.CabCode).GreaterThan(0).WithMessage("CabCode cannot be or less than 0");     RuleFor(x => x.TechnicalHeader.Ndg).NotEmpty().WithMessage("Ndg cannot be null or an empty string"); });