@Inject PersonDao is null in @FacesConverter class

Question

I am trying to get from selectOneMenu an object that has fields such as first name, last name and so on. This is my form:

<h:form>

<p:outputLabel value="Persons: " />
<p:selectOneMenu value="#{personBean.person}">
    <f:selectItem itemLabel="Select Person" itemValue="" noSelectionOption="true"/>
    <f:selectItems itemLabel="#{person.firstName}" itemValue="#{person}" var="person" value="#{personBean.persons}" />

</p:selectOneMenu>
<br /><br />
<p:commandButton value="Submit"
    action="#{personBean.showSomething()}" icon="ui-icon-check" />

I don't understand.. where am i going wrong? How can i get that object?
I've been trying for a few days but i haven't managed to fix this problem... I tried using a Converter but i kept getting NPEs.

EDIT
This is my converter:(I am trying to get the object from my postgres db with the help of my DAO)

@Named
@FacesConverter(forClass=Person.class)
public class PersonConverter implements Converter {

    @Inject
    private PersonDao personDao;

    @Override
    public Object getAsObject(FacesContext arg0, UIComponent component, String submittedValue) {
        if (submittedValue == null || submittedValue.isEmpty()) {
            return null;
        }

        try {
            Person p = personDao.findById(Long.valueOf(submittedValue));
            return p;
        } catch (NumberFormatException e) {
            throw new ConverterException(new FacesMessage(submittedValue + " is not a valid Person ID"), e);
        }
    }

    @Override
    public String getAsString(FacesContext arg0, UIComponent arg1, Object arg2) {
        if (arg2 == null) {
            return "";
        }

        if (arg2 instanceof Person) {
            return String.valueOf(((Person) arg2).getId());
        } else {
            throw new ConverterException(new FacesMessage(arg2 + " is not a valid Person"));
        }
    }

}

This is where i get a NPE Person p = personDao.findById(Long.valueOf(submittedValue));
The find() method works anywhere else... When i used the debugger i noticed that personDao is null. How can i fix this?

Only when i was using the converter. When not, `personBean.showInfo()` was not even called so it didn't return anything. — ffs, Aug 19 '15 at 19:46
please add more information. like your stacktrace where you get your NPE. Also, shouldn't itemValue be #{person}? instead of the #{person.firstName}? — Fritz, Aug 20 '15 at 02:07

score 0 · Answer 1 · answered Aug 19 '15 at 21:32

In the page:

        <p:selectOneMenu value="#{personBean.person}">
            <f:selectItem itemLabel="Select Person" itemValue="" noSelectionOption="true"/>
            <f:selectItems itemLabel="#{person.firstName}" itemValue="#{person}" var="person" value="#{personBean.persons}" />
            <f:converter binding="#{personConverter}" />
            <f:attribute name="attrpersons" value="#{personBean.persons}" />                    
        </p:selectOneMenu>

In the Person bean:

You must implement toString and equals methods.

And finally you have to add the converter class:

@Named
public class PersonConverter implements Converter{

    public PersonConverter(){}

    @Override
      public Object getAsObject(FacesContext facesContext, UIComponent component, String submittedValue) {
          List<Person> persons = (List<Person>)component.getAttributes().get("attrpersons");
        if (submittedValue.trim().equals("")) {
            return null;
        } else {
            Iterator<Person> it = persons.iterator();
            while(it.hasNext()){
                Person p = it.next();
                if(p.toString().equals(submittedValue))
                    return p;                
            }
        }
        return null;
    }

    @Override
    public String getAsString(FacesContext facesContext, UIComponent component, Object value) {
        if (value == null) {
            return "";
        } else {
            return value.toString();
        }
    }
}

@Inject PersonDao is null in @FacesConverter class

1 Answers1