CODEWITHSUNDEEP
c#asp.net-mvcasp.net-mvc-3fluentvalidation
revolutionkpi
revolutionkpi

Reputation: 2682

FluentValidation 3: Error of WithMessage string formatting

I use FluentValidation 3 and I have a strange problem when I use overloaded WithMessage methods.

A composite format string are not formatting correct. I get "true" instead of {0} in my format string. All other format items are not replaced.

For example: 

 public class MyModelValidator : AbstractValidator<MyModel>
    {
        public MyModelValidator()
        {
            RuleFor(x => x.Caption).NotNull().WithMessage("{0} ----- {1}", "one", "two" );
        }
    }

Validation string which I get is: "true----- {1}" instead of "one----- two".

Could you explain me, what is wrong in my code?

Upvotes: 1

Views: 1727

Answers (1)

Rapha&#235;l Althaus
Rapha&#235;l Althaus

Reputation: 60503

Well, response is... in the source Code.

You use this overload (not really clear in its usage, I must say) of WithMessage :

public static IRuleBuilderOptions<T, TProperty> WithMessage<T, TProperty>(this IRuleBuilderOptions<T, TProperty> rule, string errorMessage, params object[] formatArgs) {
    var funcs = ConvertArrayOfObjectsToArrayOfDelegates<T>(formatArgs);
    return rule.WithMessage(errorMessage, funcs);
    }

So "one" and "two" are changed to an array of Func<T, object>, wich, of course, will lead to strange behaviours with your code...

You should use string.Format in your case

WithMessage(string.Format("{0} ----- {1}", "one", "two" ));

By the way, FluentValidation messages are "already preformatted" : The goal to use {0} in WithMessage is to modifiy the text around {0}. For example, NotNull has a "1 argument" preformatted message. That's why your {0} is transformed to "true", I think.

Upvotes: 1

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