Validate a decimal value

Question

I was hoping to be able to do something like this:

 public class MinimumSalaryAttribute : ValidationAttribute
    {
        private readonly decimal _minValue;

        public MinimumSalaryAttribute(decimal minValue)
        {
            _minValue = minValue;
        }

        public override bool IsValid(object value)
        {
            return (decimal)value > _minValue;
        }
    }

and then in my view:

[MinimumSalary(0M)]
public decimal Salary { get; set; }

This would prevent users entering negative decimals. However, I get a compiler error: "not a valid attribute type". I understand the reason for this as described here: Why "decimal" is not a valid attribute parameter type?

What is the workaround in my vase?

Do you *really* need to use decimal here? Would you ever restrict a salary to 12.56? Just use `int`. Which means you can just use the normal `Range` attribute. — DavidG, Aug 08 '17 at 10:38
Are you sure the `IsValid` is valid? I'd say it should return true if `value >= _minValue`... — Peter B, Aug 08 '17 at 10:40
@DavidG, surely a monetary value should be a decimal - that it what it is for - isn't it? Is your suggestion just a hack? Thanks anyway. — w0051977, Aug 08 '17 at 10:42
Well yes, it's a kind of a hack, but it's the least hacky way to achieve this. Only a hack will get around the fact you can't use a decimal for an attribute parameter. — DavidG, Aug 08 '17 at 10:44
@Stephen Muecke, I was thinking about that. Are there any pitfalls to this? I cannot think of any. Thanks. — w0051977, Aug 08 '17 at 10:46

pisi1001 · Accepted Answer · 2017-08-10T10:35:58.643

1

You can use "Range" annotation; 10.50D is min value,50.80D is max value...

[Range(10.50D,50.80D,ErrorMessage ="Error min")]
public decimal Salary { get; set; }

Range attribute specifies the numeric range constraints for the value of a data field. It comes with System.ComponentModel.DataAnnotations (in System.ComponentModel.DataAnnotations.dll)

edited Aug 10 '17 at 10:35

answered Aug 08 '17 at 10:48

pisi1001

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1
5

Thanks. This appears to work. Could the downvoter explain what is wrong? – w0051977 Aug 08 '17 at 10:53
@w0051977 I would guess that the vote is because of the quality of the answer as it's just a code dump with no explanation of why it would work. – DavidG Aug 08 '17 at 10:57
@DavidG, If I saw this answer, then I would upvote it and I will. I find it clear and concise. Maybe another paragraph would of helped. Is there anything wrong with it in principle? Thanks. – w0051977 Aug 08 '17 at 10:59
@w0051977 Any post which is effectively only a code dump is not useful. This one answers your question but without explaining why you can use `double` or even that the numbers *are* `double`. So personally I don't think it's worthy of an upvote in it's current form. – DavidG Aug 08 '17 at 11:01
@DavidG, fair enough. – w0051977 Aug 08 '17 at 11:05
@w0051977 Of course, there's nothing stopping pisi1001 [edit]ing this answer to make it much better, after all that's the entire point of this site! – DavidG Aug 08 '17 at 11:06

Validate a decimal value

1 Answers1