Get error message when using custom validation attribute
Solution 1
There's no reliable way to get the error message from the attribute. Alternatively you could write a custom validation attribute:
[MyValidator(ErrorMessage = "Foo")]
public TestProperty SomeProperty { get; set; }
like this:
public class MyValidatorAttribute : ValidationAttribute
{
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
var testProperty = (TestProperty)value;
if (testProperty == null || string.IsNullOrEmpty(testProperty.Name))
{
return new ValidationResult(FormatErrorMessage(validationContext.DisplayName));
}
return null;
}
}
In this case the error message will be inferred from the custom validation attribute.
Solution 2
I know this is a little of an old post, but I will provide an better answer to the question.
The asker wants to use the CustomValidationAttribute
and pass in an error message using the ErrorMessage
property.
If you would like your static method to use the error message that you provided when decorating your property, then you return either:
new ValidationResult(string.Empty)
or ValidationResult("")
or ValidationResult(null)
.
The CustomValidationAttribute
overrides the FormatErrorMessage
of its base class and does a conditional check for string.IsNullOrEmpty
.
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marcus
Updated on September 15, 2022Comments
-
marcus over 1 year
I'm using the CustomValidationAttribute like this
[CustomValidation(typeof(MyValidator),"Validate",ErrorMessage = "Foo")]
And my validator contains this code
public class MyValidator { public static ValidationResult Validate(TestProperty testProperty, ValidationContext validationContext) { if (string.IsNullOrEmpty(testProperty.Name)) { return new ValidationResult(""); <-- how can I get the error message from the custom validation attribute? } return ValidationResult.Success; } }
So how can I get the error message from the custom validation attribute?
-
Kirby over 9 yearsYes there is a reliable way. For a better answer to the actual question asked please see my answer below.
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MTR about 8 yearsThank you. Exactly what I was looking for.