programmatically add custom validators

[Leonardo Shikida]

Hi

I can find several tutorial about how to write your own validator.

But none of them explains how to create a custom validator and add it programmatically

For example, LengthValidator is a default JSF validator and it´s added programmatically just like this

LengthValidator lengthValidator = (LengthValidator) application.createValidator(LengthValidator.VALIDATOR_ID);
lengthValidator.setMinimum(2);
someOtherComponent.addValidator(lengthValidator);

where

public static final java.lang.String VALIDATOR_ID = "javax.faces.Length";

I´ve tried writing my custom validator and assigning a unique id in faces-config.xml, when I try to add it to another component, I get

09:17:01,803 ERROR [MyBeanMB] Expression Error: Named Object: MyCustomValidator not found.
javax.faces.FacesException: Expression Error: Named Object: my.company.MyCustomValidator not found.
at com.sun.faces.application.ApplicationImpl.createValidator(ApplicationImpl.java:959)

Is there any tutorial anywhere about this? How do I write validators that can be added programmatically?

TIA

Leo K.

[Ilari Moilanen]

Hi
I tested your code and works fine for me! Using MyFaces 2.0.2.

For example I have a custom validator like this

@FacesValidator(value="dateValidator")
public class DateValidator implements Validator {

    @Override
    public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException {
    }
}    

and make a validator programmatically like you did i.e.

        FacesContext context = FacesContext.getCurrentInstance();
        Application application = context.getApplication();
        DateValidator dateValidator = (DateValidator) application.createValidator("dateValidator"); 
        log.debug(dateValidator.toString());    

What version of JSF are you using? Do you define the name of your validator in faces-config.xml or (like I did above) with @FacesValidator annotation?

[Saurabh Saxen]

Ilari Moilanen,

Do you have a fully working example project that you can attach please!

Thanks,

[Tim Holloway]

I don't understand the value of dynamically adding a validator myself. Unless you're HEAVILY into dynamic View construction, it's generally easier to just define the thing statically in faces-config.xml.

Your error message would appear to indicate that things were mostly done correctly, except that you didn't include the file /WEB-INF/classes/my/company/MyCustomValidator.class in your WAR. Or its equivalent.

[Ilari Moilanen]

Saurabh Saxen,

alas I do not have an example. All I have is code in production use.

But there should be nothing complicated in using the custom validator. As I said above I use JSF 2 (MyFaces) and the above code works as is. I do NOT have anything in the config file(s) since the @FacesValidator annotation above is enough. The validate method throws javax.faces.validator.ValidatorException if the validation fails. You can google the different classes used to find what their API says about them.

I do not use the validator programmatically anywhere, I just tested it because the original poster said that his code does not work. Instead I use the validator in UI like this:

<t:inputCalendar id="startdate" value="#{searchBean.startDate}"
				                renderAsPopup="true"              
								popupDateFormat="#{msgs.formatdateshort}"
								popupTodayDateFormat="#{msgs.formatdateshort}"
								popupWeekString="#{msgs.week}"
								popupTodayString="#{msgs.thedatetoday}"
								validator="dateValidator"
								label="#{msgs.startdate}"
								converterMessage="#{msgs.startdateinvalid}" />

(where t: is defined as xmlns:t="http://myfaces.apache.org/tomahawk")