Question

I am getting the null Converter error for what I thought was a very simple scenario:

<!-- My View -->
<ui:composition template="/template/template_v1.xhtml"
            xmlns="http://www.w3.org/1999/xhtml"
            xmlns:ui="http://java.sun.com/jsf/facelets"
                xmlns:h="http://java.sun.com/jsf/html">
<!-- Simplified for clarity -->    
<h:form>
    <div class="block-panel customer-data">
        <h:outputLabel for="txtUsername">Username:</h:outputLabel>
        <h:inputText id="txtUsername" name="Username" 
                     value="#{userBean.user.id}"
                     styleClass="text" />
        <rich:message id="errorUsername" for="txtUsername"/>
    </div>
    <!--  Other fields omitted for clarity  -->
</h:form>

/* The User Bean - simplified */
@ManagedBean
@ViewScoped
public class UserBean implements Serializable {
    private User user;

    public User getUser() {
        // Contains logic for reading a user from the database or creating a new
        // user object
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

}

/* The user Entity - Simplified */
@Entity
@Table(name = "user")
@Inheritance(strategy = InheritanceType.JOINED)
@DiscriminatorColumn(name = "user_type", discriminatorType = DiscriminatorType.STRING)
public class User implements IEntity<String>, Serializable {
private static final long serialVersionUID = 1L;

    private String id;

    @Id
    @Column(name = "username", length = 50)
    @NotNull(message = "{userIdMandatory}")
    @Size(max = 50)
    public String getId() {
        return this.id;
    }

    public void setId(String id) {
        this.id = id;
    }

}

/* The IEntity interface */
public interface IEntity<ID extends Serializable> {
    ID getId();
    void setId(final ID pId);
}

So essentially I’m trying to bind a string property of my user entity to a inputText field. As far as I’m concerned there should be no need for a conversion so I shouldn’t be getting the error I’m seeing.

Interestingly, if I add the following getter and setter to my entity:

public String getTmpId() {
    return this.id;
}

public void setTmpId(String id) {
    this.id = id;
}

And then make the necessary changes to my view to bind to tmpId rather than id, everything works as expected.

This seems like a bug to me either to do with the fact that I am binding to a getter/setter defined in an interface, defined in a generic interface or because the getter is marked with the Id attribute. I would appreciate someone else’s ideas however.

As an aside, I have inherited this design and don’t particularly like it so I may just end up refactoring it to introduce a new username property rather than trying to use the Id.

Answer 1

To the best of my knowledge I believe this is caused by an obscure bug in BeanELResolver which is used to get the type of the property being bound to – rather than returning String it is returning Serializable, for which there is no converter and hence the error I am seeing.

It’s not particularly elegant, but I have worked around this by adding a userId property to my userBean and then binding to that in my view instead of the Id property on the user entity. I then use that value to set the Id manually on the entity when I save it:

<!-- My New View -->
<ui:composition template="/template/template_v1.xhtml"
            xmlns="http://www.w3.org/1999/xhtml"
            xmlns:ui="http://java.sun.com/jsf/facelets"
                xmlns:h="http://java.sun.com/jsf/html">
<!-- Simplified for clarity -->    
<h:form>
    <div class="block-panel customer-data">
        <h:outputLabel for="txtUsername">Username:</h:outputLabel>
        <h:inputText id="txtUsername" name="Username" 
                     value="#{userBean.userId}"
                     styleClass="text" />
        <rich:message id="errorUsername" for="txtUsername"/>
    </div>
    <!--  Other fields omitted for clarity  -->

/* The New User Bean - simplified */
@ManagedBean
@ViewScoped
public class UserBean implements Serializable {
    private string userId;
    private User user;

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public User getUser() {
        // Contains logic for reading a user from the database or creating a new
        // user object
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    public void saveUser() {
        if (user.getId() == null) {
            user.setId(userId);
        }
        // Actual saving omitted for brevity
    }
}