EntityManager in custom validator

[shakenbrain]

Can you inject an EntityManager into a custom JSF validator class, assuming you've made the validator a seam component? I've tried, but the entityManager is always null.

[pmuir]

Yes, use the @Converter annotation to register your converter (rather than registering it through faces-config.xml), use the @Transactional annotation on the getAsXXX methods, and do a entityManager.joinTransaction() before accessing the entityManager. We seem to be missing docs for @Converter and @Validator so post back if you are stuck.

[shakenbrain]

Thanks for the quick response. That's fantastic. I think I'm almost there, but I'm not sure how to reference the validator from the page; it's not going to be with the <f:validator> tag, right?

@Name("prefixValidator")
@Validator
public class PrefixValidator implements javax.faces.validator.Validator {

 @In
 EntityManager entityManager;

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

 entityManager.joinTransaction();

 String prefix = (String) value;

 Query q = entityManager.createQuery("from Organization o where o.prefix = :prefix");
 q.setParameter("prefix", prefix.toUpperCase());
 if (q.getResultList().size() > 0) {
 throw new ValidatorException(makeMessage("Prefix is being used already"));
 }
 }
...
}

<s:decorate id="prefixDecorator" template="decorateField.xhtml">
 <ui:define name="label">Prefix</ui:define>
 <h:inputText id="prefix" size="4" value="#{organizationEditor.instance.prefix}" required="true" disabled="#{!organizationEditor.new}">
 <f:validator validatorId="prefixValidator"/>
 <a:support event="onblur" reRender="prefixDecorator"/>
 </h:inputText>
</s:decorate>

[shakenbrain]

Turns out that's exactly the way you do it. I had to make my validator class implement Serializable. For reference, here's the code:

@Name("prefixValidator")
@Validator
public class PrefixValidator implements javax.faces.validator.Validator, Serializable {

 @In
 EntityManager entityManager;

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

 entityManager.joinTransaction();

 String prefix = (String) value;

 Query q = entityManager.createQuery("from Organization o where o.prefix = :prefix");
 q.setParameter("prefix", prefix.toUpperCase());
 if (q.getResultList().size() > 0) {
 throw new ValidatorException(makeMessage("Prefix is being used already"));
 }
 }

 private FacesMessage makeMessage(String s) {
 FacesMessage message = new FacesMessage();
 message.setDetail(s);
 message.setSummary(s);
 message.setSeverity(FacesMessage.SEVERITY_ERROR);
 return message;
 }
}

<s:decorate id="prefixDecorator" template="decorateField.xhtml">
 <ui:define name="label">Prefix</ui:define>
 <h:inputText id="prefix" size="4" value="#{organizationEditor.instance.prefix}" required="true" disabled="#{!organizationEditor.new}">
 <f:validator validatorId="prefixValidator"/>
 <a:support event="onblur" reRender="prefixDecorator"/>
 </h:inputText>
 </s:decorate>

[monkeyden]

Now that is sweet. I feel like I just found a $20 on the ground.

[supernovasoftware.com]

Can the this be used with a SLSB to avoid the @Transactional annotation and the entityManager.joinTransaction()?

[pmuir]

Give it a go, let us know how you get on :)

[supernovasoftware.com]

It seems to work fine for a SLSB.

[nebukadnezzar]

i've got some problems with the validator...

When the onblur-event from ajax4jsf is triggered

a SelectOneMenu in the form is redrawn too and the selectItems are from an EntityQuery.
I always get an exception "the transaction is not active" in the function getResultList from the EntityQuery