How to validate number format TextField in wicket?

Question

In my maven-wicket (6.10) application I have a TextField, which has an Integer type property model. I want to set a maximum length for numberts to type into this TextField. (for example the user should write maximum 2 characters to the "age" text field)

I have tried this code:

add(new TextField<>("age",new PropertyModel<(personModel,"age"))
    .add(StringValidator.maximumLength(2)));
//age is an Integer value from a Person class, personModel is "IModel<Person>" type

but I got this exception:

java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.String
    at org.apache.wicket.validation.validator.StringValidator.getValue(StringValidator.java:87)
    at org.apache.wicket.validation.validator.StringValidator.getValue(StringValidator.java:59)
    at org.apache.wicket.validation.validator.AbstractRangeValidator.validate(AbstractRangeValidator.java:107)
    at org.apache.wicket.markup.html.form.FormComponent.validateValidators(FormComponent.java:1523)

So if the property model is not string type, I cannot use StringValidator. I have found examples, which use NumberValidator (validators), but I cannot resolve NumberValidator. I have only these validators in the source: How could I use number validator? Or am I missing something, maybe form the pom.xml's dependencies for wicket?

Answer 1

The problem you are facing is related to the way Wicket works. First it converts input text into a model object and then it performs validation.

Thus, you have to use RangeValidator instead of StringValidator

IModel<Integer> model =
    new PropertyModel<Integer>(personModel, "age");
Component ageField = new TextField<Integer>("age", model);
add(ageField).add(RangeValidator.<Integer>range(0, 99));

Note I've changes Long to Integer as I believe saving age as Long is not practical.

Also note that link to NumberValidator is for Wicket 1.4, while you are using Wicket 6. Wicket 6 is a large API change comparing to previous versions.