ChildRules() inside ForEach() ignores WithErrorCode(), uses defaults: RegularExpressionValidator, AsyncPredicateValidator, etc.

Which version of FluentValidation are you using?

<PackageReference Include="FluentValidation" Version="9.5.3" />

Which version of ASP.NET are you using?

<Project Sdk="Microsoft.NET.Sdk.Web">
<TargetFramework>netcoreapp3.1</TargetFramework>

Describe the issue that you’re having

I have a pretty heavy validator with the rules such as:

RuleFor(x => x)
    .Must((_, _, context) => CheckAccountState(context.ParentContext))
    .WithMessage("Account must be in Succeeded state")
    .WithErrorCode(ErrorCode.AccountIsNotInSucceededState)

What produces correct error:

{
    "code": "AccountIsNotInSucceededState",
    "message": "Account must be in Succeeded state"
}

and

 RuleFor(x => x.Properties.IotHubs)
     .ForEach(x => x.Must((_, iotHub, context) => CheckIotHubName(iotHub, context.ParentContext))
          .WithMessage((_, iotHub) => $"Specified Iot Hub '{iotHub.ResourceId}' must match resource id and connection string")
          .WithErrorCode(ErrorCode.IoTHubNameDoesNotMatchResourceIdOrConnectionString)

          // other rules go here

hence:

{
    "code": "IoTHubNameDoesNotMatchResourceIdOrConnectionString",
    "message": "Specified Iot Hub '...' must match resource id and connection string"
}

However then I have a rule such as this:

.ChildRules(s => s.RuleFor(p => p.ResourceId)
    .NotNull()
    .NotEmpty()
    .Matches(config.Value.Validation.IoTHubResourceId, RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase | RegexOptions.Singleline))
    .WithErrorCode(ErrorCode.IoTHubNameDoesNotMatchPattern)

What ignores the provided error code altogether:

{
    "code": "RegularExpressionValidator",
    "message": "'Resource Id' is not in the correct format."
}

And more than on one occasion:

.ChildRules(s => s.RuleFor(p => p.IoTHubConnectionString)
    .NotNull()
    .NotEmpty()
    .MustAsync((_, str, context, ct) => CheckIotHubConnectionString(str, context.ParentContext, ct))
    .WithMessage("Specified Iot Hub connection string is invalid"))
    .WithErrorCode(ErrorCode.IoTHubConnectionStringIsInvalid)

hence:

{
    "code": "AsyncPredicateValidator",
    "message": "Specified Iot Hub connection string is invalid"
}

Have a setup anything incorrectly or it’s a bug?

[jeremymeng]

@jeremymeng, sure, here’s a repro.

I believe you meant @JeremySkinner 😄

[abatishchev]

@JeremySkinner thank you so much for detailed explanation and example, that helps a lot, I got it working now.