I'm trying out JSF 2.0 (after using ICEfaces 1.8 for the past few months) and I'm trying to figure out why in JSF 2.0 my backing bean constructor gets called multiple times.
The bean is supposed to be instantiated once upon creation, but the "Bean Initialized" text shows up whenever I click the commandButton, indicating a new Bean object being instansiated.
The facelet page:
<?xml version='1.0' encoding='UTF-8' ?>
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html">
<h:body>
<div id="content">
<h:form id="form">
<h:commandButton value="Toggle" action="#{bean.toggleShowMe}"/>
</h:form>
<h:panelGrid rendered="#{bean.showMe}">
<h:outputText value="Show me!"/>
</h:panelGrid>
</div>
</h:body>
</html>
The backing bean:
#ManagedBean
#RequestScoped
public class Bean {
private boolean showMe = false;
public boolean isShowMe() {
return showMe;
}
public void setShowMe(boolean showMe) {
this.showMe = showMe;
}
public void toggleShowMe(){
System.out.println(showMe);
if(showMe==true){
showMe=false;
}else{
showMe=true;
}
}
/** Creates a new instance of Bean */
public Bean() {
System.out.println("Bean Initialized");
}
}
Thats all it is. Just a simple test. The same behaviour shows itself if I use ICEfaces 2.0 and in place of the panelGrid I use:
<ice:panelPopup visible="#{bean.showMe}">
I'd appreciate any help here. I'm at a loss to explain it.
Update: In response to Aba Dov, I #SessionScoped the bean, figuring it wouldn't be calling the constructor upon each request and ran into the same behavior. What am I missing?
You have declared the bean to be placed in the request scope and you're firing a new HTTP request everytime by the command button. Truly the bean will be created on every request.
If you want that the bean lives as long as the view itself (like as IceFaces is doing under the covers for all that ajax stuff), then you need to declare the bean view scoped (this is new in JSF 2.0).
#ManagedBean
#ViewScoped
public class Bean implements Serializable {}
In my case the problem was I imported "javax.faces.bean.ViewScoped" instead of importing "javax.faces.view.ViewScoped".
Hope it could help someone.
The bean is called every time there is a request from the page.
when you click the <h:commandButton> the form is submitted and a request is sent to the server
in order to prevent it you can use <t:saveState> or <a4j:keepAlive> tags for your been.
for example <a4j:keepAlive beanName="YourBean" />
those tags stores the bean instance in the component tree .
also make sure that your class implements Serializable. so it can be serialized
Hope this helps
The bean should be in the ViewScoped.
Related
Is there a way to execute a JSF managed bean action when a page is loaded?
If that's relevant, I'm currently using JSF 1.2.
JSF 1.0 / 1.1
Just put the desired logic in the constructor of the request scoped bean associated with the JSF page.
public Bean() {
// Do your stuff here.
}
JSF 1.2 / 2.x
Use #PostConstruct annotated method on a request or view scoped bean. It will be executed after construction and initialization/setting of all managed properties and injected dependencies.
#PostConstruct
public void init() {
// Do your stuff here.
}
This is strongly recommended over constructor in case you're using a bean management framework which uses proxies, such as CDI, because the constructor may not be called at the times you'd expect it.
JSF 2.0 / 2.1
Alternatively, use <f:event type="preRenderView"> in case you intend to initialize based on <f:viewParam> too, or when the bean is put in a broader scope than the view scope (which in turn indicates a design problem, but that aside). Otherwise, a #PostConstruct is perfectly fine too.
<f:metadata>
<f:viewParam name="foo" value="#{bean.foo}" />
<f:event type="preRenderView" listener="#{bean.onload}" />
</f:metadata>
public void onload() {
// Do your stuff here.
}
JSF 2.2+
Alternatively, use <f:viewAction> in case you intend to initialize based on <f:viewParam> too, or when the bean is put in a broader scope than the view scope (which in turn indicates a design problem, but that aside). Otherwise, a #PostConstruct is perfectly fine too.
<f:metadata>
<f:viewParam name="foo" value="#{bean.foo}" />
<f:viewAction action="#{bean.onload}" />
</f:metadata>
public void onload() {
// Do your stuff here.
}
Note that this can return a String navigation case if necessary. It will be interpreted as a redirect (so you do not need a ?faces-redirect=true here).
public String onload() {
// Do your stuff here.
// ...
return "some.xhtml";
}
See also:
How do I process GET query string URL parameters in backing bean on page load?
What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for?
How to invoke a JSF managed bean on a HTML DOM event using native JavaScript? - in case you're actually interested in executing a bean action method during HTML DOM load event, not during page load.
Another easy way is to use fire the method before the view is rendered. This is better than postConstruct because for sessionScope, postConstruct will fire only once every session. This will fire every time the page is loaded. This is ofcourse only for JSF 2.0 and not for JSF 1.2.
This is how to do it -
<html xmlns:f="http://java.sun.com/jsf/core">
<f:metadata>
<f:event type="preRenderView" listener="#{myController.onPageLoad}"/>
</f:metadata>
</html>
And in the myController.java
public void onPageLoad(){
// Do something
}
EDIT - Though this is not a solution for the question on this page, I add this just for people using higher versions of JSF.
JSF 2.2 has a new feature which performs this task using viewAction.
<f:metadata>
<f:viewAction action="#{myController.onPageLoad}" />
</f:metadata>
#PostConstruct is run ONCE in first when Bean Created.
the solution is create a Unused property and Do your Action in Getter method of this property
and add this property to your .xhtml file like this :
<h:inputHidden value="#{loginBean.loginStatus}"/>
and in your bean code:
public void setLoginStatus(String loginStatus) {
this.loginStatus = loginStatus;
}
public String getLoginStatus() {
// Do your stuff here.
return loginStatus;
}
Calling bean action from a <p:remoteCommand> will be a good idea, keep attribute autoRun="true"
Example below
<p:remoteCommand autoRun="true" name="myRemoteCommand" action="#{bean.action}" partialSubmit="true" update=":form" />
Is there a way to execute a JSF managed bean action when a page is loaded?
If that's relevant, I'm currently using JSF 1.2.
JSF 1.0 / 1.1
Just put the desired logic in the constructor of the request scoped bean associated with the JSF page.
public Bean() {
// Do your stuff here.
}
JSF 1.2 / 2.x
Use #PostConstruct annotated method on a request or view scoped bean. It will be executed after construction and initialization/setting of all managed properties and injected dependencies.
#PostConstruct
public void init() {
// Do your stuff here.
}
This is strongly recommended over constructor in case you're using a bean management framework which uses proxies, such as CDI, because the constructor may not be called at the times you'd expect it.
JSF 2.0 / 2.1
Alternatively, use <f:event type="preRenderView"> in case you intend to initialize based on <f:viewParam> too, or when the bean is put in a broader scope than the view scope (which in turn indicates a design problem, but that aside). Otherwise, a #PostConstruct is perfectly fine too.
<f:metadata>
<f:viewParam name="foo" value="#{bean.foo}" />
<f:event type="preRenderView" listener="#{bean.onload}" />
</f:metadata>
public void onload() {
// Do your stuff here.
}
JSF 2.2+
Alternatively, use <f:viewAction> in case you intend to initialize based on <f:viewParam> too, or when the bean is put in a broader scope than the view scope (which in turn indicates a design problem, but that aside). Otherwise, a #PostConstruct is perfectly fine too.
<f:metadata>
<f:viewParam name="foo" value="#{bean.foo}" />
<f:viewAction action="#{bean.onload}" />
</f:metadata>
public void onload() {
// Do your stuff here.
}
Note that this can return a String navigation case if necessary. It will be interpreted as a redirect (so you do not need a ?faces-redirect=true here).
public String onload() {
// Do your stuff here.
// ...
return "some.xhtml";
}
See also:
How do I process GET query string URL parameters in backing bean on page load?
What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for?
How to invoke a JSF managed bean on a HTML DOM event using native JavaScript? - in case you're actually interested in executing a bean action method during HTML DOM load event, not during page load.
Another easy way is to use fire the method before the view is rendered. This is better than postConstruct because for sessionScope, postConstruct will fire only once every session. This will fire every time the page is loaded. This is ofcourse only for JSF 2.0 and not for JSF 1.2.
This is how to do it -
<html xmlns:f="http://java.sun.com/jsf/core">
<f:metadata>
<f:event type="preRenderView" listener="#{myController.onPageLoad}"/>
</f:metadata>
</html>
And in the myController.java
public void onPageLoad(){
// Do something
}
EDIT - Though this is not a solution for the question on this page, I add this just for people using higher versions of JSF.
JSF 2.2 has a new feature which performs this task using viewAction.
<f:metadata>
<f:viewAction action="#{myController.onPageLoad}" />
</f:metadata>
#PostConstruct is run ONCE in first when Bean Created.
the solution is create a Unused property and Do your Action in Getter method of this property
and add this property to your .xhtml file like this :
<h:inputHidden value="#{loginBean.loginStatus}"/>
and in your bean code:
public void setLoginStatus(String loginStatus) {
this.loginStatus = loginStatus;
}
public String getLoginStatus() {
// Do your stuff here.
return loginStatus;
}
Calling bean action from a <p:remoteCommand> will be a good idea, keep attribute autoRun="true"
Example below
<p:remoteCommand autoRun="true" name="myRemoteCommand" action="#{bean.action}" partialSubmit="true" update=":form" />
I already asked this question in the WildFly forum but did not get any answers so far. So I´m trying here.
Since I upgraded from WildFly 8.1 to 8.2 I have problems with a commandButton inside a tabView connected to a bean.
Here is a simple JSF page:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:p="http://primefaces.org/ui">
<h:head></h:head>
<h:body>
<h:form>
<p:tabView binding="#{testBean.tabView}">
<p:tab title="Tab">
<p:commandButton value="Inside" action="#{testBean.testInside}"/>
</p:tab>
</p:tabView>
<p:commandButton value="Outside" action="#{testBean.testOutside}"/>
</h:form>
</h:body>
</html>
and the bean:
#Named
#SessionScoped
public class TestBean implements Serializable {
private TabView tabView = new TabView();
public TabView getTabView() {
return tabView;
}
public void setTabView(TabView tabView) {
this.tabView = tabView;
}
public void testInside() {
System.out.println("inside");
}
public void testOutside() {
System.out.println("outside");
}
}
Clicking the "Inside" button triggers testInside() two times. The "Outside" button (outside of the tabView) behaves normally and triggers it´s method only once. Removing the tabView binding eliminates the problem. I´m using PrimeFaces 4.0.
Thanks for any ideas
Jan
It's a Mojarra 'issue', introduced by a performance optimization fix in 2.2.7.
this is a Mojarra "issue", I've discovered it when working on RF-13920, it was introduced by JAVASERVERFACES-3193. The components that use binding are not recreated during a request to the server but their children are. With the original children still in place inserting the new children causes the "duplicate id" error.
So it looks like your button is added twice, but since you do not have an explicit id assigned, you do not get the duplicate id error... Might be interesting to give that a try (adding an explicit id)
The JSF specification states that binding should only be used in Request scope, so I don't think it should be treated as a bug if this fails in Conversation scope.
The last remark is the interesting one. As is posted in the next post on the jboss site:
But now I think I have a satisfying solution for this issue and I can confirm, that with request-scoped backing beans for the component binding the exception and duplicate id problem does not occur anymore, even with Mojarra 2.2.8 from Wildfly-8.2.0.Final!
This is even true if the rest of the logic for the page remains in a (say) conversation scoped bean. You just need to have a request-scoped bean for the binding attribute, which then can be referenced in EL and other beans.
Check also this post
You can try doing in other way. Use remoteCommand out of the tab with the same action of the commandButton.
Then use the JavaScript function created by the remoteCommand in the onclick event of the commandButton.
Here is the example using your code.
It's functional.
<h:form>
<p:remoteCommand id="myfun" name="myfun" action="#{testBean.testInside}" />
<p:tabView binding="#{testBean.tabView}">
<p:tab title="Tab">
<p:commandButton value="Inside" onclick="myfun();"/>
</p:tab>
</p:tabView>
</h:form>
I am using datatable on page and using binding attribute to bind it to my backing bean. This is my code :-
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:p="http://primefaces.prime.com.tr/ui">
<h:head>
<title>Facelet Title</title>
</h:head>
<h:body>
<h:form prependId="false">
<h:dataTable var="item" value="#{testBean.stringCollection}" binding="#{testBean.dataTable}">
<h:column>
<h:outputText value="#{item}"/>
</h:column>
<h:column>
<h:commandButton value="Click" actionListener="#{testBean.action}"/>
</h:column>
</h:dataTable>
</h:form>
</h:body>
</html>
This is my bean :-
package managedBeans;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import javax.annotation.PostConstruct;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;
import javax.faces.component.html.HtmlDataTable;
#ManagedBean(name="testBean")
#ViewScoped
public class testBean implements Serializable {
private List<String> stringCollection;
public List<String> getStringCollection() {
return stringCollection;
}
public void setStringCollection(List<String> stringCollection) {
this.stringCollection = stringCollection;
}
private HtmlDataTable dataTable;
public HtmlDataTable getDataTable() {
return dataTable;
}
public void setDataTable(HtmlDataTable dataTable) {
this.dataTable = dataTable;
}
#PostConstruct
public void init(){
System.out.println("Post Construct fired!!");
stringCollection = new ArrayList<String>();
stringCollection.add("a");
stringCollection.add("b");
stringCollection.add("c");
}
public void action(){
System.out.println("Clicked!!");
}
}
Please tell me why is the #PostConstruct firing each and every time i click on button? It should fire only once as long as i am on same page beacause my bean is #ViewScoped. Further, if i remove the binding attribute then everything works fine and #PostConstruct callback fires only once. Then why every time when i use binding attribute? I need binding attribute and want to perform initialisation tasks like fetching data from webservice, etc only once. What should i do? Where should i write my initialisation task?
Interesting, when you're using component binding on a view scoped bean, the view scope breaks.
I am not sure if that is a bug in JSF2, I would have to read the entire JSF2 specification first. As far now your best bet is to drop the component binding for now and pass the selected item via new EL 2.2 method argument syntax:
<h:dataTable var="item" value="#{testBean.stringCollection}">
<h:column>
<h:outputText value="#{item}"/>
</h:column>
<h:column>
<h:commandButton value="Click" action="#{testBean.action(item)}"/>
</h:column>
</h:dataTable>
See also:
How can I pass selected row to commandLink inside dataTable?
Invoke direct methods or methods with arguments / variables / parameters in EL
Benefits and pitfalls of #ViewScoped
Update (Dec 2012): this is indeed a bug in JSF2. It's a chicken-egg issue. The view scoped beans are stored in the JSF view state. So the view scoped beans are only available after restore view phase. However, the binding attribute runs during restore view phase, while the view scoped beans are not available yet. This causes creation of a brand new view scoped bean instance, which is then later replaced by the real view scoped bean which was stored in the restored JSF view state.
This is reported as JSF issue 1492 and JSF spec isssue 787 which will be fixed for JSF 2.2. Until then, your best bet is to use binding on request scoped beans exclusively, or to look for alternate ways for the particular functional requirement.
Update (Mar 2015): The JSF 2.2 fix was backported to Mojarra 2.1.18. So if you're still using JSF 2.0/2.1, you'd best upgrade to at least that version. See also a.o. What is component binding in JSF? When it is preferred to be used? and JSTL in JSF2 Facelets... makes sense?
As other said, I would say that the best thing to do is to drop component binding (you don't need it here).
But I would add that you can achieve the same as you're trying to do in a more object-oriented fashion by using action parameters, like this:
<h:commandButton value="Click" action="#{testBean.action(item)}"/>
... and in your java code:
public void action(Item item){
System.out.println("Clicked!!" + item);
}
If you have a viewscoped bean and if you want to retain values that were entered on the form or don't want postconstruct fired, you should return null from your action method.
If you return some outcome (e.g. invalid) and then point the invalid outcome to the same page using faces-config.xml, then the viewscoped bean gets recreated and thus it causes postconstruct to fire again.
Other solution:
Binding the HtmlDataTable in a request scope bean.
Inject this request scope bean in the view scope bean.
JBoss Seam use this solution for binding JSF componentes to a conversation scope component.
The balusc's answer helped me a lot, i would like to say that i had that bug with mojarra version 2.1.7, i am currently using 2.1.29-01 released in january-2015 and this bug is fixed, my problem was binding a tabview to a viewscoped bean. With this version I dont have that bug and binding and postconstruct is working fine.
I use Jboss 5.2 and i have to use mojarra 2.1.x so i hope this answer help other people in the same situation.
http://mvnrepository.com/artifact/com.sun.faces/jsf-api/2.1.29-01
http://mvnrepository.com/artifact/com.sun.faces/jsf-impl/2.1.29-01
Is there a way to execute a JSF managed bean action when a page is loaded?
If that's relevant, I'm currently using JSF 1.2.
JSF 1.0 / 1.1
Just put the desired logic in the constructor of the request scoped bean associated with the JSF page.
public Bean() {
// Do your stuff here.
}
JSF 1.2 / 2.x
Use #PostConstruct annotated method on a request or view scoped bean. It will be executed after construction and initialization/setting of all managed properties and injected dependencies.
#PostConstruct
public void init() {
// Do your stuff here.
}
This is strongly recommended over constructor in case you're using a bean management framework which uses proxies, such as CDI, because the constructor may not be called at the times you'd expect it.
JSF 2.0 / 2.1
Alternatively, use <f:event type="preRenderView"> in case you intend to initialize based on <f:viewParam> too, or when the bean is put in a broader scope than the view scope (which in turn indicates a design problem, but that aside). Otherwise, a #PostConstruct is perfectly fine too.
<f:metadata>
<f:viewParam name="foo" value="#{bean.foo}" />
<f:event type="preRenderView" listener="#{bean.onload}" />
</f:metadata>
public void onload() {
// Do your stuff here.
}
JSF 2.2+
Alternatively, use <f:viewAction> in case you intend to initialize based on <f:viewParam> too, or when the bean is put in a broader scope than the view scope (which in turn indicates a design problem, but that aside). Otherwise, a #PostConstruct is perfectly fine too.
<f:metadata>
<f:viewParam name="foo" value="#{bean.foo}" />
<f:viewAction action="#{bean.onload}" />
</f:metadata>
public void onload() {
// Do your stuff here.
}
Note that this can return a String navigation case if necessary. It will be interpreted as a redirect (so you do not need a ?faces-redirect=true here).
public String onload() {
// Do your stuff here.
// ...
return "some.xhtml";
}
See also:
How do I process GET query string URL parameters in backing bean on page load?
What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for?
How to invoke a JSF managed bean on a HTML DOM event using native JavaScript? - in case you're actually interested in executing a bean action method during HTML DOM load event, not during page load.
Another easy way is to use fire the method before the view is rendered. This is better than postConstruct because for sessionScope, postConstruct will fire only once every session. This will fire every time the page is loaded. This is ofcourse only for JSF 2.0 and not for JSF 1.2.
This is how to do it -
<html xmlns:f="http://java.sun.com/jsf/core">
<f:metadata>
<f:event type="preRenderView" listener="#{myController.onPageLoad}"/>
</f:metadata>
</html>
And in the myController.java
public void onPageLoad(){
// Do something
}
EDIT - Though this is not a solution for the question on this page, I add this just for people using higher versions of JSF.
JSF 2.2 has a new feature which performs this task using viewAction.
<f:metadata>
<f:viewAction action="#{myController.onPageLoad}" />
</f:metadata>
#PostConstruct is run ONCE in first when Bean Created.
the solution is create a Unused property and Do your Action in Getter method of this property
and add this property to your .xhtml file like this :
<h:inputHidden value="#{loginBean.loginStatus}"/>
and in your bean code:
public void setLoginStatus(String loginStatus) {
this.loginStatus = loginStatus;
}
public String getLoginStatus() {
// Do your stuff here.
return loginStatus;
}
Calling bean action from a <p:remoteCommand> will be a good idea, keep attribute autoRun="true"
Example below
<p:remoteCommand autoRun="true" name="myRemoteCommand" action="#{bean.action}" partialSubmit="true" update=":form" />