Can't write custom WhenNotNull extension in v10

FluentValidation version

10.0.0

ASP.NET version

No response

Summary

Now that IValidationContext doesn’t expose PropertyValue, I can’t write custom WhenNotNull, WhenNotEmpty, etc., extension methods.

In v9 I defined these (and more) extension methods:

public static IRuleBuilderOptions<T, TProperty> WhenNotNull<T, TProperty>(this IRuleBuilderOptions<T, TProperty> rule, ApplyConditionTo applyConditionTo = ApplyConditionTo.AllValidators)
{
    return rule.Configure(config => config.ApplyCondition(context => context.PropertyValue != null, applyConditionTo));
}

public static IRuleBuilderOptions<T, string> WhenNotEmpty<T>(this IRuleBuilderOptions<T, string> rule, ApplyConditionTo applyConditionTo = ApplyConditionTo.AllValidators)
{
    return rule.Configure(config => config.ApplyCondition(context => !string.IsNullOrEmpty((string)context.PropertyValue), applyConditionTo));
}

And used them extensively like this:

public class MyClassValidator : AbstractValidator<MyClass>
{
    public MyClassValidator()
    {
        RuleFor(x => x.MyDictionary).MaximumSize(50, 40, 500).WhenNotNull(); // MaximumSize validates maxElements, maxKeyLength, maxValueLength for an IDictionary
        RuleFor(x => x.MyString).MaximumLength(10).WhenNotEmpty();
    }
}

I read the upgrade guide (and also #1672) but still couldn’t get it to work.

Thanks!

[JeremySkinner]

I’ve pushed out 10.0.1 to nuget with this change. I had to do it slightly differently and expose a public method rather than exposing the PropretyFunc directly. You can call this new method inside your extension like this:

public static IRuleBuilderOptions<T, TProperty> WhenNotNull<T, TProperty>(this IRuleBuilderOptions<T, TProperty> rule, ApplyConditionTo applyConditionTo = ApplyConditionTo.AllValidators)
{
    return rule.Configure(config => 
    {
      config.ApplyCondition(context => config.GetPropertyValue(context.InstanceToValidate) != null, applyConditionTo);
    });
}

It’s untyped, returning object but there’s no way around this unfortunately as the TProperty on the extension method won’t match the property value when working with collections (inside RuleForEach collections, TProperty references the type of the current collection element, rather than the collection property type returned by the PropertyFunc, so the new method has to return object in order to correctly receive the collection reference when called as part of RuleForEach).

[gabrielmaldi]

Just upgraded to 10.0.1, refactored my extension methods to use GetPropertyValue and now everything works perfectly!

Thanks a lot!