Develop Reference

JSF Link not working (with Primefaces)

Sorry, really really basic question...
I've got a list of 'messageboard threads' that I display on a page. I want to be able to click on one of them and redirect to a page which displays the details for that thread. I'm struggling despite googling it for a while...
(I'm using PrimeFaces by the way)
Here's the relevant code from my 'list' page:
<p:commandLink value="#{thread.title}" action="#{messageboardBean.showThread()}">
<f:param name="threadId" value="#{thread.id}" />
</p:commandLink>
(it's in an h:form element)
This is part of my named bean (other methods work fine)
...
#ManagedProperty(value="#{param.threadId}")
private Long threadId;
...
public String showThread() {
System.out.println("id is " + getThreadId());
return "messageboard/list";
}
...
As you can see my method isn't implemented yet, but it's not even being called. Please can someone tell me why?
I tried with an h:link too by the way, same (or similar) problem.
Thanks!
UPDATE - Solved
Thanks to the help below, here is my solution (I've renamed 'messageboard' to 'discussion').
The link is generated using this code
value: what to display on the page, in my case the title of my discussion
outcome: refers to edit.xhtml, the faces file I want to go to
...and the [request] param is going to be called 'threadId' and has a value of the id attribute in my 'thread' object.
In the edit.xhtml page, I've got this
<f:metadata>
<f:viewParam name="threadId" value="#{viewDiscussionBean.threadId}" />
<f:event type="preRenderView" listener="#{viewDiscussionBean.loadDiscussion}" />
</f:metadata>
Note that 'threadId' is the same as the param name in the first page, and it is bound to my viewDiscussionBean's threadId property.
Then once the params are all set on my bean, I call the loadDiscussion method of my viewDiscussionBean. Since it now has the threadId property, it's able to do this (see below)
My viewDiscussionBean has the following managed property (I think the viewParam tag sets this, rather than the other way around).
#ManagedProperty(value="#{param.threadId}")
private Long threadId;
private Discussion thread;
So once that's set, this method is able to run (because it now has an ID)
public String loadDiscussion() {
thread = mbDao.find(threadId);
return "edit";
}
This just uses a DAO (using Hibernate) to look up the discussion thread with that ID, and set it in the bean. And then...
In my edit.xhtml page, I can access values in the discussion thread using things like
<h:outputText value="#{viewDiscussionBean.thread.message}" />
Voila! Thanks.

There are many possible caused for an UICommand action not being invoked. You can find them all here: commandButton/commandLink/ajax action/listener method not invoked or input value not updated Among others a missing form, a nested form, or a conversion/validation error elsewhere in the form, being in a datatable whose datamodel is not properly preserved, etcetera.
As to your particular functional requirement, better is to use a <h:link>. A command link issues a POST request which does in your particular case not end up with a bookmarkable URL with the thread ID in the URL. A <h:link> creates a fullworthy link which is bookmarkable and searchbot-indexable.
E.g.
<h:link value="#{thread.title}" outcome="messageboard/list">
<f:param name="threadId" value="#{thread.id}" />
</h:link>
This doesn't require a form nor an action method. You only need to move that #ManagedProperty to the bean associated with messageboard/list, or maybe replace it by <f:viewParam> in the messageboard/list view which allows for finer-grained validation/conversion.
See also:
Communication in JSF2 - Processing GET request parameters
When should I use h:outputLink instead of h:commandLink?
ViewParam vs #ManagedProperty(value = "#{param.id}")

Your best bet it probably to go with BalusC's answer and use <h:link>. However, I have some thoughts about the behavior you're seeing.
Primefaces <p:commandLink> (like <p:commandButton>) uses ajax by default. Therefore, there won't be any actual navigation resulting from returning an outcome from your action. This could make it look like your action isn't being invoked. Try adding ajax=false to your <p:commandLink>.
When using <h:link>, navigation is resolved when the link is rendered rather than when it's clicked. Modifying your example:
<h:link value="#{thread.title}" outcome="#{messageboardBean.showThread()}">
<f:param name="threadId" value="#{thread.id}" />
</h:link>
showThread() will be called (I think) when the view containing the link is being rendered. If you're not checking at the right time, this may also make it look like the method is being called.
In both cases, this doesn't explain why you wouldn't see the message to System.out at all, but I know I've tried that thinking it was fail-safe and still not seen the output, which all depends on your container, configuration, how you launched it, etc.

Binding process occurs before action is taken in JSF 2

I'm using PrimeFaces with JSF 2.0, I have this layout:
<h:panelGroup layout="block" id="panelGroup" binding="#{bean.boundPg}" />
<p:commandButton value="Update" action="#{bean.updateMe}" update="panelGroup" />
in which, the bean is SessionBean. By using log4j to debug I found out that the binding process called getBoundPg before executing the action updateMe. So the view is always out-of-date.
Do you know why and how to reverse that order? Thanks!
------------- Edit ---------------
I'm making a web app for a quiz game.
<h:panelGroup layout="block" id="pgContents" binding="#{bean.boundContents}" />
<p:commandButton value="Prev page" action="#{bean.prevPage}" update="pgContents" />
<p:commandButton value="Next page" action="#{bean.nextPage}" update="pgContents" />
pgContents contains many h:pannelGroups, each sub-group contains a label showing the content of a quiz, a h:inputText for the player to give their answer. Because of some reasons, I had to generate the children of pgContents programmatically.
The Prev page and Next page buttons will retrieve the prev/next group of quiz
Below is the bean (getters & setters are skipped)
#ManagedBean(name = "bean")
#SessionScoped
public class LessonHelper {
private int currentPage;
private HtmlPanelGroup boundContents;
public void prevPage() {
// decrease currentPage
// fetch contents
// add children for boundContents (label, inputText)
}
// nextPage() is similar
}
My problem is that, when I click the Prev/Next button, the getter getBoundContents is called first in binding process, and the prevPage()/nextPage() is called later, which cause the content always out-of-date.

Because this is the natural way, as you can see in this wonderful tutorial by BalusC: http://balusc.blogspot.com/2006/09/debug-jsf-lifecycle.html
Tell me exactly what do you want to do, show what's inside that bean and a solution to your problem will be found!

How can I populate data in JSF [duplicate]

This question already has answers here:
How to populate options of h:selectOneMenu from database?
(5 answers)
Closed 6 years ago.
Up until now, I have always been using JSP to display pages. When a user request for a page such as "Add Item", I will load all Item Category in an Array List and display them as options in select box like this:
<select name="category>
<%
ArrayList<Category> categories = (ArrayList<Category>) request.getAttribute("categories");
for (Category c : data) {
%>
<option value="<%= c.getId() %>"><%= c.getName() %></option>
<%
}
%>
</select>
From the book "JavaServer Faces 2.0, The Complete Reference", I learnt that: "JSF enforces clean Model-View-Controller separation by disallowing the inclusion of Java code in markup pages". Hence, I'd be very grateful if someone could show me how I can handle the above task using JSF since I cannot use Java code as I have always done anymore.
Best regards,
James Tran

JSF 2.0 uses Facelets as the templating method, which in a nutshell is XHTML with some additional elements.
While technically you can perform method calls from Facelets, in general the idea is to access a JavaBean with proper geter/setter methods to perform your data moving. You can accomplish this as the below segment of code shows:
<h:selectOneMenu value="#{backingBean.selectedCategory}">
<f:selectItems value="#{backingBean.categoryList}"/>
</h:selectOneMenu>
On the bean side of things, you want to expose a bean to JSF using either faces-config (which is largely discouraged) or a mechanism such as CDI or the Managed Bean infrastructure. I highly recommend you look into using SEAM if you go the CDI route, as it will unify the (currently really strangely disparate) Managed Bean and CDI frameworks, so you can use JSF scopes in CDI, and have CDI beans available in JSF scopes.
#ManagedBean(name="backingBean")
#ViewScoped
public class MyJavaBackingBean {
#ManagedProperty("#{param.categories}")
protected List<String> categoryList
public void setSelectedCategory(String value) {
this.selectedCategory = value;
}
public String getSelectedCategory() {
return this.property;
}
...
}
You can also make the getters do lazy initialization of your values (for pulling categoryList from a database for example), and use some other JSF annotations to do various initialization tasks.
You can also code action methods which return a String representing the JSF action (this gets coded into your faces-context.xml file) to take after returning. Phase listeners on the backing bean can also be called at various stages of page rendering, validation and submission, getting you very fine grained control.
categoryList in the above example is not limited to basic types of course, and <f:selectItems> also has some syntax for writing out the textual version of your select items, so you can make some quite complex expressions to display each item in a friendly way.

Create a bean and make it known with e.g. #Named so you can refer to it from your JSF script. Then give that bean a method returning the data you want to show, and invoke that method from your JSF script in a location where that data is expected e.g. a loop construct.

Store the data you want to display in a Java list, and expose that list as a property of a backing bean. The use the appropriate JSF tag to display that property.

In JSF 2.0 you can include the tag h:selectOneMenu in which you get the value where you store the item value selected. The value in f:selectItems could be a collection of any object the most of times SelectItem in this object your declare value object and the label to display.
<h:selectOneMenu value="#{backingBean.selectedvalue}">
<f:selectItems value="#{backingBean.List}"/> </h:selectOneMenu>
if you required values and labels of another object in you must declare
<h:selectOneMenu value="#{backingBean.selectedvalue}">
<f:selectItems value="#{backingBean.ListCar}" var="car" itemLabel="#{car.model}" itemValue="#{car.modelId}"/>
</h:selectOneMenu>

JSF property transfer from backing bean A to backing bean B

I'm getting deeper into JSF 2.0 at the moment and lacking a bit of understanding about the "transport" of managed bean properties from one view to the other. I searched a bit but haven't found a really good example, so if anyone could point me to a tutorial or explain the things a little bit I'd really grateful.
So here is my scenario:
I'm developing a small playground calendar application. The first view select.xhtml contains the calendar selector, where the user can pick a specific date:
<html>
...
<h:form>
<!-- Calendar selector from primefaces -->
<p:calendar value="#{calendarSelect.date}" mode="inline" navigator="true" />
<p:commandButton value="Show entries for date" action="day" />
...
My corresponding backing bean looks like this:
#ManagedBean(name="calendarSelect")
#RequestScoped
public class CalendarSelectComponent {
private Date date = null;
... // Getters and setters
Now when I submit the form from select.xhtml I'm forwarded to day.xhtml
<html>
...
<h:form>
The current day ist:
<h:outputText value="#{calendarEdit.date}">
<f:convertDateTime pattern="dd.MM.yyyy" />
</h:outputText>
The backing bean now looks like this:
#ManagedBean(name="calendarEdit")
#ViewScoped
public class CalendarEditComponent implements Serializable {
private Date date = null;
private CalendarEntryBean currentEntry = null;
private List<CalendarEntryBean> allEntries = null;
....
I am now trying to solve the problem: How do I transfer the date parameter from the selector to the editor?
I've tried a number of options, one was this:
<p:commandButton value="Show entries for date" action="day" />
<f:setPropertyActionListener target="#{calendarEdit.date}" value="#{calendarSelect.date}" />
</p:commandButton>
A debugger shows, that indeed, the date property of the calendarEdit is populated with the value from calendarSelect, but since day.xhtml is a new view, a new CalendarEditComponent backing bean is being created and not the one I've populated with the date from the selector in the select view.
I've read that one solution would be to create a SessionScoped backing bean that does retain all it's values. But this is not the way I think it's supposed to work, because I don't really need the information in the session, I simply want it to "travel" from A to B. Another downside with the session based approach is that I can only use one selector and one editor per session - which I think isn't acceptible if you think of multi window browsing and so on.
I really don't think I'm the first one encountering such a scenario and I'm sure that JSF provides an elegant solution for this but I haven't been able to find that solution.
So once again, if anyone knows how to approach this - I'm listening! ;-)

The <f:setPropertyActionListener> is executed during invoke action phase of the form submit. So it expects that the value is still there at that point. But since your select bean is request scoped, it isn't there during form submit anymore. You want instead to pass a request parameter which get inlined in the output during render response. You can do this with <f:param>.
<p:commandButton value="Show entries for date" action="day" />
<f:param name="date" value="#{calendarSelect.dateAsString}" />
</p:commandButton>
It'll be available as request parameter (note that it only understands Strings, due to the nature of HTTP). You could let JSF set request parameters as managed properties, but since your edit bean is view scoped, this isn't possible with #ManagedProperty. You've got to gather it yourself by ExternalContext.
String dateAsString = externalContext.getRequestParameterMap().get("date");
True, that's clumsy. I would just have used the same bean and view for this and toggle visibility of select/edit forms by rendered attribute. The edit view is after all not directly openable/bookmarkable by a simple GET, isn't it? ;)

Passing data from request ManagedBeans in JSF

I'm somewhat confused about the lifecycle of ManagedBeans of type "request".
In this example i'm using one request bean "userBean" to fill this page and one request bean "userEditBean" to fill the following edit page.
<h:form>
<h:panelGrid border="1" columns="2">
<h:outputText value="Name" />
<h:outputText value="#{userBean.user.name}" />
...
</h:panelGrid>
<h:commandButton value="Edit" action="edit" actionListener="#{userEditBean.init}">
<f:attribute name="user" value="#{userBean.user}"/>
</h:commandButton>
</h:form>
When i press the Edit button a userEditBean is created but the attribute map resolves "user" to null.
Does this mean that the attribute EL is resolved after the userBean has already been destroyed? How can i pass values from incoming beans to outgoing beans?

You're setting the attribute value with an expression, not a static value. Whenever you request the value, the expression will be re-evaluated again. The userBean.user apparently isn't present in the subsequent request. You need to ensure that it is there (in other words, the constructor of the userBean should ensure that the user is been created and set.
There are however alternatives. One of the best is to use Tomahawk's <t:saveState> for that. Add it somewhere in the page:
<t:saveState value="#{userBean.user}" />
That said, I agree with Bozho that the whole approach is a bit strange, but that's another story. You may however get lot of useful ideas out either of the following articles: Communication in JSF and/or Using Datatables. Good luck.

request scope means the bean lives during one request. And you fill your edit page (1st request), and send the edited user (2nd request).
In addition to that, <f:attribute> sets tha attributes in the parent component, not in the request. So in your code the attributes will be found in the button.getAttributes() (if you have bound your button).
Furthermore, it is strange to have an actionListener method named init. Since you don't need the event, you can set the action to be the method which will do the editing operation, and make that method return the navigation-rule you want.