In my actual project I have noticed that the method that populates the ui:repeat tag, is being invoked when there is a post call, even though the ui:repeat is not part of the submitted form.
I have been trying to check againts the jsf documentation if that is the way it should work, with no success.
Is it supposed to work this way?
Thanks in advance.
Sample code:
When the button is clicked the method anotherBean.getCollection is being invoked:
<h:form id="firstForm">
<h:commandButton action="#{someBean.someAction}"/>
</h:form>
<h:form id="secondForm">
<ui:repeat var="product" value="#{anotherBean.populatCollection}" >
<!-- CODE -->
</ui:repeat>
</h:form>
In first place, a getter method shouldn't be populating the value at all. A getter method should, as its name says, just return the already-populated value.
You're not terribly clear on the concrete functional requirement, i.e. when exactly did you intend to populate the value, but one way would be moving the populating logic to the #PostConstruct of #{anotherBean}.
#ManagedBean
#ViewScoped
public class AnotherBean {
private List<Something> getCollection; // Terrible variable name by the way.
#PostConstruct
public void init() {
getCollection = populateItSomehow();
}
public List<Something> getGetCollection() {
return getCollection; // See, just return the property, nothing more!
}
}
See also:
Why JSF calls getters multiple times
So, it looks like ui:repeat tag is invoking the methods assigned to its value argument when a post is done, no matter if the post is done from another form.
Thanks for the help.
Related
Update: for those flagging this to be closed as a duplicate, the supposed duplicate question is nothing like what I am asking. My problem is I do not know until render time what the question set will be, how many questions there will be or what the question types will be so I cannot use the technique described in the "possible duplicate" answer.
Part of our JSF 2.x application has a requirement to render sets of questions to the user where the questions and the question types are not known until run-time. e.g we have something like (getters/setters omitted for clarity) :
public class QuestionSet {
private List<Section> sections;
}
public class Section {
private String sectionTitle;
private List<Question> questions;
private SectionStatus status; // e.g. UNANSWERED, CURRENTLY_ANSWERING,ANSWERED, COMPLETED
}
public class Question {
private String questionText;
private QuestionType questionType; // E.G TEXT, RADIO, LIST, CHECKBOX
private List<String> options; // for RADIO/LIST/CHECKBOX types
private List<String> answers;
}
We need to render each section in a seperate div, depending on it's status (e.g. UNANSWERED would display a div with just the title, ANSWERED would display a div with the section title and a green tick mark, and CURRENTLY_ANSWERING would render a div with the section title and then each question with the appropriate input control based on the question type.
The questions are also dynamic during the run - e.g. if a user answers yes to a radio button question, this may prompt further sub-questions.
I am currently doing this using a binding, i.e.
<h:panelGroup binding = "#{bean.panelGroup}" />
and within the bean's getPanelGroup creating the component tree by hand usin things like HtmlPanelGroup, HtmlOutputText, UIInput with ValueExpressions etc. which works fine but on reading some of BalusC's answers, particlarly to this question: How does the 'binding' attribute work in JSF? When and how should it be used? I am wondering if there is a "better" approach?
One of the things that concerns me is that the getter is called during RECREATE_VIEW for reasons explained in the linked question (after invoking the method referred to in the binding) so unless I take steps to, in RECREATE_VIEW phase, just return the component I created in the last RENDER_RESPONSE phase, this introduces unnecessary expense of recreating something I've just created.
In this case, it also seems pointless that JSF calls my setter to set the thing I just gave it in the getter for the bound property. (my bean is View scope as I will need to use ajax for some of the functionality our users require)
Thoughts/opinions (Especially from the ever helpful BalusC) greatly appreciated...
I don't see much reason to use component binding in this case. You can decide in your view what to render and how. You can have <ui:fragment>/<c:if> to conditionally render elements basing on question type, <ui:repeat>/<c:forEach> to handle the question set, etc.
So, if I understand the workflow correctly, your question set will be determined in e.g. post constructor method:
#PostConstruct
public void init() {
questionSet = service.get();//get it somehow
}
Then you'll have a set of sections and each of these section will contain questions, or answers, and validity is to be checked via AJAX. If I understand you right, then you can have the following view:
<h:form id="q-set">
<ui:repeat value="#{bean.questionSet.sections}" var="section">
<div>#{section.title}</div>
<div class="#{section.status eq 'UNANSWERED' ? 'section-unanswered' : ... }"/>
<ui:fragment rendered="#{section.status eq 'ANSWERED' ?}"><div class="tick"/></ui:fragment> ...
<ui:fragment rendered="#{section.status eq 'ANSWERED' ?}">
<ui:repeat value="#{section.questions}" var="question">
<div>#{question.title}</div>
<ui:fragment rendered="#{question.type eq 'RADIO'}">
<h:selectOneRadio value="#{question.answers[0]}" validator="...">
<f:selectItems value="#{question.options}" var="opt" itemLabel="#{opt}" ... />
<f:ajax ...>
</h:selectOneRadio>
</ui:fragment>
...
</ui:repeat>
</ui:fragment>
</ui:repeat>
</h:form>
It looks like you are going to have too much logic/conditions in your view.
What about generating the view programmatically on the Java side ?
For tricky parts you may resort to JavaScript and JSON.
Project uses Spring Webflow and JSF (PrimeFaces). I have a p:commandButton with f:attribute
<p:commandButton disabled="#{editGroupMode=='edit'}" action="edit_article_group" actionListener="#{articleGroupManager.setSelectedRow}" ajax="false" value="Edit">
<f:attribute name="selectedIndex" value="${rowIndex}" />
</p:commandButton>
Backend code (Spring injected bean):
#Service("articleGroupManager")
public class ArticleGroupManagerImpl implements ArticleGroupManager{
public void setSelectedRow(ActionEvent event) {
String selectedIndex = (String)event.getComponent().getAttributes().get("selectedIndex");
if (selectedIndex == null) {
return;
}
}
}
The attribute "selectedIndex" is always null. Anybody knows what happened here? Thank you.
The variable name "rowIndex" suggests that you've declared this inside an iterating component, such as <p:dataTable>.
This is then indeed not going to work. There's physically only one JSF component in the component tree which is reused multiple times during generating HTML output. The <f:attribute> is evaluated at the moment when the component is created (which happens only once, long before iteration!), not when the component generates HTML based on the currently iterated row. It would indeed always be null.
There are several ways to achieve your concrete functional requirement anyway. The most sane approach would be to just pass it as method argument:
<p:commandButton value="Edit"
action="edit_article_group"
actionListener="#{articleGroupManager.setSelectedRow(rowIndex)}"
ajax="false" disabled="#{editGroupMode=='edit'}" />
with
public void setSelectedRow(Integer rowIndex) {
// ...
}
See also:
JSTL in JSF2 Facelets... makes sense?
How can I pass selected row to commandLink inside dataTable?
Unrelated to the concrete problem, I'd in this particular case have used just a GET link with a request parameter to make the request idempotent (bookmarkable, re-executable without impact in server side, searchbot-crawlable, etc). See also Communication in JSF 2.0 - Processing GET request parameters.
In a previous question BalusC gave me good advice on how a button, in place of a commandButton is useful for non ajax navigation. In particular it updates the destination address in the http: position which is useful for the user to bookmark a page.
I tried to use this information to my advantage until I came upon a problem. In a button I tried to use outcome="#{backing.something}" to find out that it gives me a null result. This looks like a timing problem in that action="#{}" is evaluated only when the button is pressed whereas outcome apparently wants a fixed string which gets checked when the page is loaded.
So I went back to commandButton with ajax="false". This has a problem that my navigation address is the page I came from, not the one I am navigating to. This is the wrong bookmark for the user.
I appreciate all the help I have received in stackoverflow on my learning exercise.
Ilan
The <h/p:button outcome> is not intented to invoke a bean action method, but to contain the outcome string directly. Any EL in there is evaluated immediately as a value expression. So the method behind it would immediately be invoked when you just open the page containing the <h/p:button>.
There are in your particular case basically two ways to invoke a bean action method on navigation. If you need to invoke it before the navigation takes place and the action isn't intented to be re-invoked everytime when the enduser reopens/reloads the GET request, then make it a POST-Redirect-GET request. It's a matter of adding faces-redirect=true to the outcome value in query string syntax.
E.g.
<p:commandButton action="#{bean.submit}" ... />
with
public String submit() {
// ...
return "nextpage?faces-redirect=true";
}
This way the browser will be redirected to the target page after POST, hence the enduser will see the target URL being reflected in the address bar.
Or if you need to invoke the action everytime when the enduser reopens/reloads the GET request, do the job in the (post)constructor or preRenderView listener method of the request/view scoped backing bean instead.
E.g.
<p:button outcome="nextpage" ... />
with
#ManagedBean
#RequestScoped
public class NextpageBacking {
public NextpageBacking() {
// In constructor.
}
#PostConstruct
public void onPostConstruct() {
// Or in postconstructor (will be invoked after construction AND injection).
}
public void onPreRenderView() {
// Or before rendering the view (will be invoked after all view params are set).
}
// ...
}
The pre render view listener method needs to be definied as follows in the nextpage
<f:event type="preRenderView" listener="#{nextpageBacking.onPreRenderView}" />
See also:
What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for?
Communication in JSF 2.0 - Processing GET request parameters
Can you guys help me to explain the reason why the method is called multiple times when I used the h:dataTable in facelet page.
<h:dataTable id="listTable" styleClass="pageView_listForm"
value="#{ClassName.dataFactory(topic)}" border="2" rules="rows"
var="item" width="100%" cellpadding="1" cellspacing="0" rowClasses="panelRowOdd,panelRowEven" >
//Body
</h:dataTable>
Bean class
#ManagedBean (name="ClassName")
#SessionScoped
public class ClassName{
...
public DataModel <Person> dataFactory(String topic){
DataModel items = null;
..........
// This block code gets the list of Person
..........
return items;
}
}
I was launching the page when it called the method dataFactory multiple times. I did not know exactly what happen here? Is it a bug from JSF or my implementation.Can you guy help me?
Thank you.
when happens with Datatable, we should take care that such a method should not contain much business logic, Or Database interactions which are costly.
here i found some useful discussions....
Why JSF calls getters multiple times
Why is BackingBean method called multiple times when requesting facelet?
This
and here
Calling a method multiple times when using h:dataTable in JSF
Edited question...
Hello,
I would like to load a .xhtml file of my composite component from a backing bean, and add it to the page dynamically. The name of the .xhtml file comes form a variable.
Ex.:
public MyBean (){
String componentFile = "myCompositeComponent.xhtml"
public String addComponentToPage(){
//how do that?...
return null;
}
}
Thank you!
That's not possible. A composite component is template-based and can only be used in views. Your best bet is to repeat exactly the JSF code which you've originally written in the composite component in the model. Better would be to create a full worthy #FacesComponent class which extends UIComponent, complete with a #FacesRenderer. True, it's a tedious and opaque job, but this way you'll end up with a component which is reuseable in both the view and the model by a single code line.
An -ugly- alternative is to place all possible components in the view and use the rendered attribute.
<my:component1 rendered="#{bean.myComponentType == 'component1'}" />
<my:component2 rendered="#{bean.myComponentType == 'component2'}" />
<my:component3 rendered="#{bean.myComponentType == 'component3'}" />
...
Wrap this if necessary in a Facelets tag file so that it can be hidden away and reused in several places.
I don't understand why do you want to add a composite component from a backing bean. I guess you want to make it visible dynamically in case of an event, but for that there is AJAX reRender.
For example you can do the following:
<h:panelGroup id="composite" rendered="#{myBean.renderComponent}">
<my:compositecomponent/>
</h:panelGroup>
The renderComponent property stores a boolean value. You can switch that value and reRender composite with for e.g. Richfaces's <a4j:commandLink>.
Hope that helps, Daniel