How to override the default error message for int using FluentValidation?-CodePudding

I have a problem with overriding the default error message when validating an InputNumber. When the field is empty, I get the following message:

"The field FieldName must be a number.".

The documentation says you should call WithMessage on a validator definition. I tried calling WithMessage on NotEmpty and NotNull as shown below but it doesn't change the default message and I didn't see any other method that could check if the field is a number.

RuleFor(model => model.FieldName)
    .NotEmpty()
    .WithMessage("empty")
    .NotNull()
    .WithMessage("null");

Any help is much appreciated, thanks.

CodePudding user response：

The messages specified with WithMessage() are only used when the preceding validation fails, in your case NotEmpty() and NotNull().

The error your are receiving "The field FieldName must be a number." indicated that the value received is not a number while the property FieldName is a numeric type.

CodePudding user response：

I have a problem with overriding the default error message when validating an InputNumber. When the field is empty, I get the following message:

Well, let's consider few things in regards of int. It shouldn't allow empty value if you define data-type as int. Thus, in case of InputNumber we have no logical ground for .NotEmpty().

Logic: 1: Either, we should check if it is a null only when we would allow null value. For isntance:

public int? InputNumber { get; set; }

So we can handle as below:

.NotNull()
.WithMessage("Null Is not accepted")

Logic: 2: Or we can check if the InputNumber is valid input. In this scenario we can do something like:

 .GreaterThan(0)
 .WithMessage("InputNumber must be greater than 0.");

Complete Scenario For An int? InputNumber:

public class OverrideDefaultErrorMessageForInt : AbstractValidator<User>
    {
        public OverrideDefaultErrorMessageForInt()
        {
        
                 RuleFor(x => x.InputNumber)
                .NotNull()
                .WithMessage("Null Is not accepted")
                .GreaterThan(0)
                .WithMessage("InputNumber must be greater than 0.");
              
                
                                                                   
        }
        
    }

Output: