RangeValidator Can't Count?

Just few days ago, my friend at work found a peculiar error message in ASP.NET RangeValidator control. He was trying to validate length of a string in a TextBox. Controls on page definded as follows:

<asp:TextBox runat="server" ID="TB" />
<asp:RangeValidator runat="server" ID="RV" 
MinimumValue="3" MaximumValue="20" 
ControlToValidate="TB" Type="String" />

What he got was a best error message ever:

"The MaximumValue 20 cannot be less than the MinimumValue 3"

That's right! 20 cannot be less than 3!

Interesting isn't it?

I made some research of my own and I've found out that sane people should not look inside RaneValidator's (and other related classes) code! What it does inside is it uses a String.Compare to check if ranges are ok.

Of course, the problem are not the ranges, but the Type property of a validator. If set to String, it treates minimum and maximum values as strings and compares them as such - meaning that it compares character by character instead of just number to number.

That explains, why my friend got the error, but it certainly does not justify the text of the message! It might take long hours for an inexperienced developer to find where the problem lies. Come on Microsoft! You can do better than that!

Funny thing is that I never even thought about using RangeValidator to ensure string length, but suggested RegularExpressionValidator right from the start .

Add to del.icio.us