Login/Register
Invoke JSF managed bean action on page load
Asked Answered
Solved jsfactiononloadmanaged-bean
G

4

69

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.

Gallard answered 15/3, 2010 at 23:19 Comment(3)
duplicate stackoverflow.com/questions/1686821/… – Ashcroft
Not sure though, there is ambiguity in the question. As long as he don't explicitly state "download file on page load", or "fire new request on page load", or so, then the mentioned topic is not necessarily a dupe of this. – Kilburn
Correct answer is given here https://mcmap.net/q/17366/-execute-backing-bean-action-on-load – Havener
K
107

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:

Kilburn answered 15/3, 2010 at 23:59 Comment(4)
your answer is great and fit to my need... But one question... In my D. constructor I am adding such a content that will be visible on view side (on the same jsp). In this case my jsp doesn't view this information on very first time. But if I reload a page that content is visible. Can we handle this thing any way? – Bozo
This answer will only work once if I have a session scope. Is there a better way to implement this for session scope bean? – Mealtime
@huahsin68, the answers provided are going to work as expected. As BalusC said, use the last two examples for beans that have a wider scope than view-scope. For those curious about where to place the f:metadata information in a ui:composition page: Right after the ui:composition and before a possible ui:define or alike tags. – Platform
you should use "f:event" instead of "f:viewAction", if you are using jsf 2.0+ – Makedamakefast
H
14

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>
Hedgcock answered 3/12, 2014 at 11:59 Comment(0)
G
11

@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;
}
Gambit answered 23/11, 2010 at 12:14 Comment(1)
So, you're using alone session scoped beans? That's a Bad Practice. Plus, your example is poor. Getters can be called more than once in bean's life and shouldn't be abused to execute business stuff. Just use a request scoped bean and do the job in constructor or @PostConstruct. – Kilburn
E
2

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" />
Elephus answered 8/5, 2018 at 5:22 Comment(1)
Why is this a 'good idea' when the solutions above do not need an additional roundtrip. – Intangible

© 2022 - 2024 — McMap. All rights reserved.