JSF 2 basic @RequestScoped CRUD

Question

i have these simple pages:

list.xhtml

<h:form id="form">  
    <h:dataTable value="#{testBean.model}" var="elem">
        <h:column>
            <f:facet name="header">code</f:facet>
            #{elem.code}
        </h:column>
        <h:column>
            <f:facet name="header">description</f:facet>
            #{elem.description}
        </h:column>
        <h:column>
            <f:facet name="header">action</f:facet>
            <h:commandButton action="#{testBean.edit(elem)}" value="edit"/>
        </h:column>
    </h:dataTable>
</h:form>

edit.xhtml

<h:form id="form">
    <h:panelGrid columns="2">
        <h:outputLabel value="code"/>
        <h:inputText value="#{testBean.selection.code}"/>

        <h:outputLabel value="description"/>
        <h:inputText value="#{testBean.selection.description}"/>
    </h:panelGrid>

    <h:commandButton action="#{testBean.update}" value="update"/>
</h:form>

and this bean:

@ManagedBean
public class TestBean implements Serializable
{
    private static final long serialVersionUID = 1L;

    @EJB
    private PersistenceService service;
    private Object selection;
    private List<UnitType> model;

    @PostConstruct
    public void init()
    {
        model = service.findAll(UnitType.class);
    }

    public String edit(Object object)
    {
        System.out.println(Tracer.current(object));
        setSelection(object);
        return "edit";
    }

    public String update()
    {
        System.out.println(Tracer.current(selection));
        return "list";
    }

    // getters and setters
}

so the table is rendered, when i click one of the "edit" buttons it navigates to "edit.jsf" showing filled input, but when i click the "update" buttons it gives me this error:

javax.el.PropertyNotFoundException: /test2/edit.xhtml @27,54 value="#{testBean.selection.code}": Target Unreachable, 'null' returned null

note that i know how to implement a @ViewScoped interface to manage CRUD operations, but this is a simple proof of concept that i need to better understand JSF lifecycle.

so i want "testBean" to be @RequestScoped

UPDATE trying with f:viewParam, still not understanding...

list.xhtml

<?xml version="1.0" encoding="ISO-8859-1"?>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core">
    <h:head>
        <title>test list</title>
    </h:head>

    <h:body>
        <h:messages/>

        <h:form id="form">
            <h:dataTable value="#{testBean2.model}" rows="10" var="elem">
                <h:column>
                    <f:facet name="header">converterString</f:facet>
                    #{elem.converterString}
                </h:column>
                <h:column>
                    <f:facet name="header">first name</f:facet>
                    #{elem.firstName}
                </h:column>
                <h:column>
                    <f:facet name="header">last name</f:facet>
                    #{elem.lastName}
                </h:column>
                <h:column>
                    <f:facet name="header">action</f:facet>
                    <h:commandButton action="#{testBean2.edit}" value="edit">
                        <f:param name="entity" value="#{elem.converterString}"/>
                    </h:commandButton>
                    <h:commandButton action="#{testBean2.edit2}" value="edit2">
                        <f:param name="entity" value="#{elem.converterString}"/>
                    </h:commandButton>
                </h:column>
            </h:dataTable>
        </h:form>
    </h:body>
</html>

edit.xhtml

<?xml version="1.0" encoding="ISO-8859-1"?>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core">
    <f:metadata>
        <f:viewParam id="entityParam" name="entity" value="#{testBean2.selection}" converter="entityConverter" required="true"/>
    </f:metadata>

    <h:head>
        <title>test edit</title>
    </h:head>

    <h:body>
        <h:messages/>

        <h:form id="form">
            <h:panelGrid columns="2">
                <h:outputLabel value="selection"/>
                <h:outputText value="#{testBean2.selection.converterString}"/>

                <h:outputLabel value="firstName"/>
                <h:inputText value="#{testBean2.selection.firstName}"/>

                <h:outputLabel value="lastName"/>
                <h:inputText value="#{testBean2.selection.lastName}"/>
            </h:panelGrid>

            <h:commandButton action="#{testBean2.update}" value="update" ajax="false">
                <f:param name="entity" value="#{testBean2.selection.converterString}"/>
            </h:commandButton>
        </h:form>
    </h:body>
</html>

testBean2.java

@ManagedBean
public class TestBean2 implements Serializable
{
    private static final long serialVersionUID = 1L;

    @EJB
    private PersistenceService service;

    private Object selection;
    private List<Person> model;

    @PostConstruct
    public void init()
    {
        Tracer.out();
        model = service.queryAll(Person.class);
    }

    public String edit()
    {
        JsfUtils.addSuccessMessage("edited");
        return "edit";
    }

    public String edit2()
    {
        JsfUtils.addSuccessMessage("edited");
        return "edit?faces-redirect=true&amp;includeViewParams=true";
    }

    public void update()
    {
        Tracer.out(selection);
        JsfUtils.addSuccessMessage("updated");
    }

    // getters and setters
}

if i press "edit" button it goes to edit page, but selection is null and no message is showed.

if i press "edit2" button it goes to edit page, but selection is null, showing required message and the url is edit.jsf?entity=

what am i doing wrong?

Read this you will get idea [Difference between View and Request scope in managed beans][1] [1]: http://stackoverflow.com/questions/6025998/difference-between-view-and-request-scope-in-managed-beans — Pradeep Gamage, Aug 16 '12 at 11:47
i already know the difference. i'm asking something different. please read the question carefully. — Michele Mariotti, Aug 16 '12 at 11:53
Hi Michele, Have you been able to solve the above issue? I am using the request scope to do CRUD. I am getting the same error as you got. — Unknown, Nov 04 '14 at 05:15
Hi @Madhava, I posted what I found as an answer. Nevertheless it is simpler to implement CRUD using at least `@ViewScope` beans, but this PoC can be a suggestion for something more advanced. Hope it helps you :) — Michele Mariotti, Nov 04 '14 at 09:05
Thank you for your comment . I have already implemented using View Scope and it work well too. But I wanted to use @RequestScope and here update and delete does not work for me :( — Unknown, Nov 04 '14 at 09:10

score 1 · Answer 1 · answered Aug 16 '12 at 12:05

1

As my understand, when your second request come to testBean, selection Object is null. If you run this with session bean you may not get this error.

answered Aug 16 '12 at 12:05

Pradeep Gamage

585
4
8
21

for the second time, read my question CAREFULLY. it's written in bold that i want "testBean" to be @RequestScoped – Michele Mariotti Sep 05 '12 at 10:26

score 0 · Answer 2 · edited Aug 28 '12 at 06:22

0

The way I see it, there's no clean way to achieve what you want.

I'll suggest you simply pass around an Id attr between requests as a simple request parameter. So in your post constructor, check if the parameter value is set and based on that, perform a look in your persistence layer.

Alternatively, using the setup you already have, bind the:

<h:inputText value="#{testBean.selection.code}"/>

component to your backing bean and call getValue() on it when necessary. Either way, still untidy.

If you find any other way, please let us know.

edited Aug 28 '12 at 06:22

Mihai Iorga

39,330
16
106
107

answered Aug 28 '12 at 03:45

kolossus

20,559
3
52
104

you're right, it seems it's impossible to achieve it in a clean way, i tried everything i know. your second solution is something i havn't tried, interesting but still too much industrious. but worth an upvote :) – Michele Mariotti Aug 28 '12 at 08:50

score 0 · Accepted Answer · edited May 23 '17 at 12:27

Finally I found a way: data will be in a long scope, bean in short.

Note that this is just a proof of concept, not a real use case. And be aware, when dealing with @RequestScope beans, of PrimeFaces lazy DataTable model scope

@ManagedBean
public class TestBean
{
    @EJB
    private PersistenceService service;

    @ManagedProperty("#{viewScope.item}")
    private Item item;

    @ManagedProperty("#{sessionScope.model}")
    private EntityDataModel<Item> model;

    @PostConstruct
    public void init()
    {
        if(model == null)
        {
            model = new EntityDataModel<Item>(Item.class);
            Faces.setSessionAttribute("model", model);
        }
    }

    public String update()
    {
        Faces.getFlash().setKeepMessages(true);

        try
        {
            item = service.update(item);
            Faces.setViewAttribute("item", item);

            JsfUtils.addSuccessMessage("updated");

            return "view?faces-redirect=true&includeViewParams=true";
        }
        catch(Exception e)
        {
            e.printStackTrace();
            JsfUtils.addErrorMessage(e);
        }

        return null;
    }

    // getters and setters, other actions, ...
}

list.xhtml

<p:dataTable value="#{testBean.model}" var="elem" ...>
    ...

    <p:column exportable="false" toggleable="false" headerText="#{bundle.actions}">

        <!-- two techniques available for navigation -->

        <p:button outcome="view?id=#{elem.converterString}" icon="#{icons.view}" />

        <p:commandButton rendered="#{user.isEditAllowed(elem)}"
            action="edit?faces-redirect=true&amp;includeViewParams=true" process="@form"
            icon="#{icons.edit}">
            <f:param name="id" value="#{elem.converterString}" />
        </p:commandButton>
    </p:column>
</p:dataTable>

view.xhtml

<f:metadata>
    <o:viewParam id="itemId" name="id" value="#{viewScope.item}" required="true"
        converter="entityConverter" />
</f:metadata>

<ui:composition template="/WEB-INF/templates/template.xhtml">
    <ui:define name="content">
        <p:panelGrid columns="2">
            <h:outputLabel value="#{bundle.name}" />
            <h:outputText value="#{item.name}" />

            ...
        </p:panelGrid>

        <p:button outcome="list" value="#{bundle.list}" icon="#{icons.list}" />

        <p:button rendered="#{user.isEditAllowed(item)}" 
            outcome="edit?id=#{item.converterString}" value="#{bundle.edit}"
            icon="#{icons.edit}" />
    </ui:define>
</ui:composition>

edit.xhtml

<f:metadata>
    <o:viewParam id="itemId" name="id" value="#{viewScope.item}" required="true"
        converter="entityConverter" />
</f:metadata>

<ui:composition template="/WEB-INF/templates/template.xhtml">
    <ui:define name="content">
        <p:panelGrid columns="2">
            <h:outputLabel value="#{bundle.name}" />
            <h:panelGroup>
                <p:inputText id="name" value="#{item.name}" />
                <p:message for="name" />
            </h:panelGroup>

            ...
        </p:panelGrid>

        <p:commandButton process="@form" update="@form" action="#{testBean.update}" 
            value="#{bundle.update}" icon="#{icons.update}" />

        <p:button outcome="view?id=#{item.converterString}" value="#{bundle.cancel}" 
            icon="#{icons.cancel}" />
    </ui:define>
</ui:composition>

I did not see this at the first place. I will check this. Thank you. — Unknown, Nov 04 '14 at 09:16

JSF 2 basic @RequestScoped CRUD

3 Answers3