Spring MVC property/field binding exception

Question

I am using Spring MVC 2.5 and for my model/bean class, at the moment, I use server side validation. One of the validation I wanted to do is check if some of the inputs are not numeric (0-9). The user may input non-numeric characters like "abcd" instead of '1234'.

I have a @Pattern which only accepts positive BigDecimal (it represents dollar amount).

public class OfferSettingBean implements Serializable {


private static final String NUMBER_WITH_DECIMAL_PLACES_ONLY="^\\d+([.]\\d+)?$";

//org.hibernate.validator.pattern
@Pattern(regex = NUMBER_WITH_DECIMAL_PLACES_ONLY, message = "invalid.amount")
    private BigDecimal offerSize;
//the rest of the code goes here including setter and getter methods
}

jsp page

 <input type="text" name="offerSize" id="offerSize" value="${offerSetting.offerSize}" placeholder="$"  />

The problem with my code is, if the user enters a non number character like "asdfsd" it doesnt even reach to the point where it should check the pattern.

Failed to convert property value of type [java.lang.String] to required type [java.math.BigDecimal] for property offerSize; nested exception is java.lang.NumberFormatException

I think the problem is before checking the pattern it binds the string value to BigDecimal which makes it fail.

One ugly solution might be in the offerSize setter method I can check the coming value and do something if it is not a number. But I dont like that one.

What is a better way to deal with such kind of binding problems?

FYI: I know I am going to do client side validation (using JQuery) latter on. Now, I assume the user by passes the client side validation in some way.

Answer 1

The error message is self-explainable. @Pattern can be used for validation of String arguments. Numbers ( int , double , BigDecimal etc) are parsed automatically and do not need special validation.

So, just remove your pattern or make your field String and parse it yourself. (The second solution is bad).

BTW are you sure you indeed need BigDecimal to operate with money? Do you know how double big is? I think that it is big enough to hold total amount of money that have been ever printed in whole world during latest 5 thousand years.

Answer 2

I think the problem is before checking the pattern it binds the string value to BigDecimal which makes it fail.

Yep!

What is a better way to deal with such kind of binding problems?

Not sure what you mean here. There was an error. The error was caught. All seems well. What behavior would you prefer?

FYI: I know I am going to do client side validation (using JQuery) latter on. Now, I assume the user by passes the client side validation in some way.

Even later, one is better off validating both client-side and server-side, IMO. There are many ways client-side validation can fail, both innocent and malicious, and even if that weren't the case, it is nice to be able to reuse server-side code without worrying about all the validation being gone because it was located in client-side Java script.