Validator.TryValidateObject Not Validating RangeAttribute

Given the following object,

public class Question
{
    [Required]
    public string QuestionText { get; set; }

    [Range(1, 5)]
    public int Difficulty { get; set; }        
}

With the following Validation Code

ICollection<ValidationResult> results = new List<ValidationResult>();
Question question = new Question();
ValidationContext ctx = new ValidationContext(question, null开发者_如何学Python, null);
Validator.TryValidateObject(question, ctx, results);
// results.Length = 1

Why does Range attribute not create a validation error when Required does (the value is 0 obviously)?

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Ah so it would seem I need to specify validateAllProperties = true

Validator.TryValidateObject(question, ctx, results, true);

Incidentally what was throwing me off was the fact I had an abstract base class with another property in it and without validateAllProperties the Validator will stop on the first error of ALL superclasses too. So you will get a validation error for each superclass (in my case 2)

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Validator.TryValidatorObject(instance, validationContext, validationResults) calls Validator.TryValidateObject(instance, validationContext, validationResults, validateAllProperties) with validateAllProperties = false.

When validateAllProperties is false, only the RequiredAttribute will be validated.