Passing parameter from one page to another - The scope of the object referenced by expression is shorter than the referring managed beans error

Question

I am trying to pass a parameter from one page to another, but when i press the button "Details" it gives me this error: "Unable to create managed bean agencyDetailBean. The following problems were found: - The scope of the object referenced by expression #{agency}, request, is shorter than the referring managed beans (agencyDetailBean) scope of session"

This is part from my .xhtml page:

<p:dataGrid var="agency" value="#{agencyBean.agencyList}" columns="1"
    rows="5" paginator="true" paginatorPosition="bottom">
    <p:growl id="growl" showDetail="true" />
    <p:fieldset legend="${agency.tUser.name}" toggleable="true">
        <p:ajax event="toggle" listener="#{fieldsetBean.handleToggle}"
            update="growl" />
        <h:panelGrid columns="2" cellpadding="3" cellspacing="1">
            <h:panelGrid columns="2" cellpadding="3" cellspacing="1">
                Name: <h:outputText value="${agency.tUser.name}" />
                Phone: <h:outputText value="${agency.tUser.phone}" />
            </h:panelGrid>

            <h:commandButton value="Details" action="agencyDetail">
                <f:setPropertyActionListener target="#{agencyBean.tAgency}"
                    value="${agency}" />
            </h:commandButton>
        </h:panelGrid>

    </p:fieldset>
</p:dataGrid>

My 1st bean:

@ManagedBean(name = "agencyBean")
@SessionScoped
public class AgencyBean implements Serializable {

    private TAgency tAgency = new TAgency();
    private List<TAgency> agencyList;

    public List<TAgency> getAgencyList() {
        return agencyList;
    }

    public void setAgencyList(List<TAgency> agencyList) {
        this.agencyList = agencyList;
    }

    @PostConstruct
    public void init() {
        EntityManager em = HibernateUtil.getEntityManager();
        Query q = em.createQuery("select u from TAgency u");
        agencyList = q.getResultList();
    }

    public TAgency gettAgency() {
        return tAgency;
    }

    public void settAgency(TAgency tAgency) {
        this.tAgency = tAgency;
    }
}

My 2nd bean class:

@ManagedBean(name = "agencyDetailBean", eager = true)
@SessionScoped
public class AgencyDetailBean implements Serializable {
    private static final long serialVersionUID = 1L;

    @ManagedProperty(value = "#{tAgency}")
    private AgencyBean agencyBean;

    private TAgency tAgency;

    public TAgency gettAgency() {
        if (agencyBean != null) {
            tAgency = agencyBean.gettAgency();
        }
        return tAgency;
    }

    public void setAgencyBean(AgencyBean agency) {
        this.agencyBean = agency;
    }
}

Initially, the .xhml page was like this and it worked.

<p:growl id="growl" showDetail="true" />
<c:forEach items="#{agencyBean.agencyList}" var="agency">
    <p:fieldset legend="${agency.tUser.name}" toggleable="true">
        ...
            <h:commandButton value="Details" action="agencyDetail">
                <f:setPropertyActionListener target="#{agencyDetailBean.agency}"<br/>
                    value="${agency}" />
            </h:commandButton>
        </h:panelGrid>
    </p:fieldset>
</c:forEach>

Any suggestion what is the problem and how to fix it? Thanks in advance!

Answer 1

Using @ManagedBean, you cannot inject beans with smaller scope into beans with bigger scope. For your case, inject the @SessionScoped into the @RequestScoped. Then you can update any properties of the @SessionScoped from the @RequestScoped bean.

Regarding your update, in the 2nd bean, you cannot get tAgency from a getter like that. The following function would do the job.

@PostConstruct
public void init() {
    tAgency = agencyBean.gettAgency();
}