I'm trying to create a button that once clicked will change a property in a bean.
<h:commandButton type="button" action="#{loginBean.withdraw}" id="thousand" class="buttons" style="top:180px;left:570px;">
<f:setPropertyActionListener target="#{loginBean.withdrawAmount}" value="1000" />
</h:commandButton>
public class LoginBean {
int withdrawAmount;
This method only works when I omit the type="button" from the commandButton, but with the type="button" it doesn't work and I'm not sure why.
I need the type="button" to be there , is there any way to keep it and still make it work ?
There is an error in your facelet snippet:
There is no such attribute as class for <h:commandButton>. Possibly you meant styleClass.
As for the problem you have, you have to:
Either provide a setter method for the withdrawAmount property
public void setWithdrawAmount(int withdrawAmount) {
this.withdrawAmount = withdrawAmount;
}
and your facelet should look like:
<h:commandButton type="submit"
action="#{loginBean.withdraw}"
id="thousand"
styleClass="buttons"
style="top:180px;left:570px;">
<f:setPropertyActionListener target="#{loginBean.withdrawAmount}"
value="1000" />
</h:commandButton>
Or, you can get rid of the <f:setPropertyActionListener> and add a statement the changes the value of the withdrawAmount as a first line of the #{loginBean.withdraw} method.
In this case your facelet snippet should look like:
<h:commandButton type="submit"
action="#{loginBean.withdraw}"
id="thousand"
styleClass="buttons"
style="top:180px;left:570px;" />
and your LoginBean#withdraw() method should start with the statement, that changes the withdrawAmount value:
public String withdraw() {
this.withdrawAmount = 1000;
//the remaining logic.
}
Personally, I would prefer the first option.
More info:
< h:commandButton > tag reference
JSF Core Tag :setPropertyActionListener vs attribute vs param
The type is the entire reason why you're having this issue. I'm posting this answer because the accepted answer doesn't explain why you're experiencing the issue.
<h:commandButton/> is designed to work in 3 modes:
submit: This is the default mode that the button is set to. This mode sends an HTTP POST request to the server that triggers the JSF request processing lifecycle. It's only this mode that enables you to trigger backing bean methods(using the action or actionListener attributes).
button: This mode triggers a GET request in the application. As GET requests go, this mode is mostly suited for navigation, i.e. requesting another view or page. In this mode, there's no easy/straightforward way to execute backing bean code, or trigger the JSF request processing lifecycle. This is your current issue
reset: This mode simply resets the value of all input components within its enclosing <h:form/>
Reference:
JSF2 Command Button VDL
JSF redirect via commandButton
Difference between h:button and h:commandButton
Related
I need to navigate from one page to another on button click. It works if I do it like this
<h:commandButton value="Search" action="pageTwo.xhtml" />
but I need to do other things and not just navigate. When I try to use a function
<h:commandButton value="Search" actionListener="#{myLittleBean.doForward}" />
public String doForward() {
// ...
return "pageTwo";
}
it just reloads the pageOne. Where is my mistake?
Your mistake is referencing the action method as an action listener instead of a real action. An action listener isn't intented to execute business actions and perform navigation. An action listener is intented to prepare some conditions required for the real action, such as setting a property.
If you just fix the wrong attribute,
<h:commandButton value="Search" action="#{myLittleBean.doForward}" />
then everything should go well.
See also:
Differences between action and actionListener
I think This is the problem of your ManagedBean
you can also try this one:
**public String doForward() {
// ...
return ("pageTwo.xhtml");
}**
if it does not work then use explicit ManagedBean
How can I open new tab when user clicks p:commandButton? I also want to pass some parameters to new page using FlashScope. Here's the code:
<h:form>
<p:commandButton value="open new tab" action="#{myBean.newTab}"/>
</h:form>
public String newTab() {
Faces.setFlashAttribute("foo", bar);
return "otherView";
}
On the otherView page I use f:event type="preRenderView" to read Flash parameters.
Two notes:
I need to use FlashScope, not URL parameters.
If possible, I don't want to change newTab() and preRenderView() methods.
Thanks for help
Use target="_blank" on the form to tell the browser that the synchronous response of the form should be presented in a new (blank) tab/window. You only need to turn off ajax behaviour of the <p:commandButton> in order to make it a synchronous request.
<h:form target="_blank">
<p:commandButton value="open new tab" action="#{myBean.newTab}" ajax="false" />
</h:form>
No changes are necessary in the backing beans, it'll just work as you intented. I would only recommend to use POST-Redirect-GET pattern in the action method.
return "otherView?faces-redirect=true";
Otherwise the new tab would show the URL of the originating page and a F5 would re-invoke the POST. Also, this way the flash scope is also really used as it is been designed for (if you didn't redirect, just storing in request scope was been sufficient).
Update: as per the comments, the view scoped bean in the initial tab/window get killed this way. by returning a String navigation case outcome. That's right, if you'd like to keep the view scoped bean alive, replace the navigation case by a Faces#redirect() call (assuming that it's indeed OmniFaces which you're using there for Faces#setFlashAttribute()). You only need to set Flash#setRedirect() to true beforehand to instruct the flash scope that a redirect will occur.
public void newTab() throws IOException {
Faces.setFlashAttribute("foo", bar);
Faces.getFlash().setRedirect(true);
Faces.redirect("otherView.xhtml");
}
In JSF 2, what is the difference between h:button and h:commandButton ?
<h:button>
The <h:button> generates a HTML <input type="button">. The generated element uses JavaScript to navigate to the page given by the attribute outcome, using a HTTP GET request.
E.g.
<h:button value="GET button" outcome="otherpage" />
will generate
<input type="button" onclick="window.location.href='/contextpath/otherpage.xhtml'; return false;" value="GET button" />
Even though this ends up in a (bookmarkable) URL change in the browser address bar, this is not SEO-friendly. Searchbots won't follow the URL in the onclick. You'd better use a <h:outputLink> or <h:link> if SEO is important on the given URL. You could if necessary throw in some CSS on the generated HTML <a> element to make it to look like a button.
Do note that while you can put an EL expression referring a method in outcome attribute as below,
<h:button value="GET button" outcome="#{bean.getOutcome()}" />
it will not be invoked when you click the button. Instead, it is already invoked when the page containing the button is rendered for the sole purpose to obtain the navigation outcome to be embedded in the generated onclick code. If you ever attempted to use the action method syntax as in outcome="#{bean.action}", you would already be hinted by this mistake/misconception by facing a javax.el.ELException: Could not find property actionMethod in class com.example.Bean.
If you intend to invoke a method as result of a POST request, use <h:commandButton> instead, see below. Or if you intend to invoke a method as result of a GET request, head to Invoke JSF managed bean action on page load or if you also have GET request parameters via <f:param>, How do I process GET query string URL parameters in backing bean on page load?
<h:commandButton>
The <h:commandButton> generates a HTML <input type="submit"> button which submits by default the parent <h:form> using HTTP POST method and invokes the actions attached to action, actionListener and/or <f:ajax listener>, if any. The <h:form> is required.
E.g.
<h:form id="form">
<h:commandButton id="button" value="POST button" action="otherpage" />
</h:form>
will generate
<form id="form" name="form" method="post" action="/contextpath/currentpage.xhtml" enctype="application/x-www-form-urlencoded">
<input type="hidden" name="form" value="form" />
<input type="submit" name="form:button" value="POST button" />
<input type="hidden" name="javax.faces.ViewState" id="javax.faces.ViewState" value="...." autocomplete="off" />
</form>
Note that it thus submits to the current page (the form action URL will show up in the browser address bar). It will afterwards forward to the target page, without any change in the URL in the browser address bar. You could add ?faces-redirect=true parameter to the outcome value to trigger a redirect after POST (as per the Post-Redirect-Get pattern) so that the target URL becomes bookmarkable.
The <h:commandButton> is usually exclusively used to submit a POST form, not to perform page-to-page navigation. Normally, the action points to some business action, such as saving the form data in DB, which returns a String outcome.
<h:commandButton ... action="#{bean.save}" />
with
public String save() {
// ...
return "otherpage";
}
Returning null or void will bring you back to the same view. Returning an empty string also, but it would recreate any view scoped bean. These days, with modern JSF2 and <f:ajax>, more than often actions just return to the same view (thus, null or void) wherein the results are conditionally rendered by ajax.
public void save() {
// ...
}
See also:
How to navigate in JSF? How to make URL reflect current page (and not previous one)
When should I use h:outputLink instead of h:commandLink?
Differences between action and actionListener
h:button - clicking on a h:button issues a bookmarkable GET request.
h:commandbutton - Instead of a get request, h:commandbutton issues a POST request which sends the form data back to the server.
h:commandButton must be enclosed in a h:form and has the two ways of navigation i.e. static by setting the action attribute and dynamic by setting the actionListener attribute hence it is more advanced as follows:
<h:form>
<h:commandButton action="page.xhtml" value="cmdButton"/>
</h:form>
this code generates the follwing html:
<form id="j_idt7" name="j_idt7" method="post" action="/jsf/faces/index.xhtml" enctype="application/x-www-form-urlencoded">
whereas the h:button is simpler and just used for static or rule based navigation as follows
<h:button outcome="page.xhtml" value="button"/>
the generated html is
<title>Facelet Title</title></head><body><input type="button" onclick="window.location.href='/jsf/faces/page.xhtml'; return false;" value="button" />
This is taken from the book - The Complete Reference by Ed Burns & Chris Schalk
h:commandButton vs h:button
What’s the difference between h:commandButton|h:commandLink and
h:button|h:link ?
The latter two components were introduced in 2.0 to enable bookmarkable
JSF pages, when used in concert with the View Parameters feature.
There are 3 main differences between h:button|h:link and
h:commandButton|h:commandLink.
First, h:button|h:link causes the browser to issue an HTTP GET
request, while h:commandButton|h:commandLink does a form POST. This
means that any components in the page that have values entered by the
user, such as text fields, checkboxes, etc., will not automatically
be submitted to the server when using h:button|h:link. To cause
values to be submitted with h:button|h:link, extra action has to be
taken, using the “View Parameters” feature.
The second main difference between the two kinds of components is that
h:button|h:link has an outcome attribute to describe where to go next
while h:commandButton|h:commandLink uses an action attribute for this
purpose. This is because the former does not result in an ActionEvent
in the event system, while the latter does.
Finally, and most important to the complete understanding of this
feature, the h:button|h:link components cause the navigation system to
be asked to derive the outcome during the rendering of the page, and
the answer to this question is encoded in the markup of the page. In
contrast, the h:commandButton|h:commandLink components cause the
navigation system to be asked to derive the outcome on the POSTBACK
from the page. This is a difference in timing. Rendering always
happens before POSTBACK.
Here is what the JSF javadocs have to say about the commandButton action attribute:
MethodExpression representing the application action to invoke when
this component is activated by the user. The expression must evaluate
to a public method that takes no parameters, and returns an Object
(the toString() of which is called to derive the logical outcome)
which is passed to the NavigationHandler for this application.
It would be illuminating to me if anyone can explain what that has to do with any of the answers on this page. It seems pretty clear that action refers to some page's filename and not a method.
I want to implement a situation where the user enter a URL, and if a specified condition is true in my managed bean this URL will be opened in a new web page.
I found this possibility:
The “h:link” tag is useful to generate a link which requires to interact with the JSF “outcome” , but lack of “action” support make it hard to generate a dynamic outcome.
The “h:commandLink” tag is suck, the generated JavaScript is really scary! Not recommend to use this tag, unless you have a solid reason to support. But it supports the “action” attribute, which is what “h:link” lack of.
The “h:outputLink” is useful to generate a link which does not require to interact with the JSF program itself.
At last, it will be perfect if the “action” attribute is added into the “h:link“.
But I didn't find a way to launch the open web page from my managed bean after the condition is verified.
I'm using JSF2.0, Facelets and PrimeFaces 3.4.
To open the target in a new window using one of those link components, you need to specify target="_blank" attribute, but this will already open the target in a new window at the moment you click the link and does thus not depend on the response. You basically need to open the target in a new window at the moment the response has been arrived. The only way is returning a JavaScript window.open() call to the response so that it get executed in the webbrowser.
In standard JSF, you could just render JavaScript's window.open() conditionally.
<h:form>
<h:inputText value="#{bean.url}" />
<h:commandButton value="submit" action="#{bean.submit}">
<f:ajax execute="#form" render="#form" />
</h:commandButton>
<h:outputScript rendered="#{bean.valid}">window.open('#{bean.url}')</h:outputScript>
</h:form>
with
private String url;
private boolean valid;
public void submit() {
valid = validate(url);
}
// ...
In PrimeFaces, you could use RequestContext#execute() to specify JavaScript code which needs to be executed on complete of the response.
<h:form>
<p:inputText value="#{bean.url}" />
<p:commandButton value="submit" action="#{bean.submit}" />
</h:form>
with
private String url;
public void submit() {
if (validate(url)) {
RequestContext.getCurrentInstance().execute("window.open('" + url + "')");
}
}
// ...
Unrelated to the concrete problem: the ranty statements which you cited there are seemingly written by someone who know nothing about HTTP/HTML basics (limitations of GET vs POST and so on). Please take them with a good grain of salt.
Here is the problem: actionlistener does not want to be fired
#ManagedBean(name="hotelsController")
#SessionScoped
public class HotelsController implements Serializable {
public void requestHotelAvail(ActionEvent event) {
request = new Request(df.format(arrivalDate), df.format(departureDate));
}
}
and xhtml
<h:panelgroup id="rooms"/>
<h:form id="hotelSearch">
<p:commandButton actionListener="#{hotelsController.requestHotelAvail}" value="submit" update="rooms" />
</h:form>
I have tried everything I could search of changed #managedbean to #component set import to import javax.faces.event.ActionEvent;
But it still does not fire anything.
Form is in a p:accordion and when used with h:commandbutton it works fine
EDIT: sorry for mislead. rooms updates after click but actionListener is not fired. so rooms will not get any new data. Important code in requestHotelAvail needs to be fired before updating rooms and its not.
EDIT2: PrimeFaces 2.2.1 - I've read whole manual to primefaces but theres no explanation to this as I've done all that it states
I've tried using action instead of actionListener without ActionEvent but it never do anything. using <h:commandbutton action="#{hotelscontroller.requestHotelAvail}"/> works great but I want that ajax engine to refresh only that rooms panelgroup
UPDATE: Now it works. Form couldn't be in <p:accordion> but why and how to enable it there? Form now I'll work without it.
I suspect the different behavior from h:commandLink comes from ajax/non-ajax processing.
By default - if you don't use f:ajax - h:commandLink is non-ajax and entire page is rerendered. Primefaces p:commandLink is using ajax and you indicate rooms as component to be updated. In your case rooms is outside form so it should rather be addressed as :rooms (mind the colon) instead of just rooms.
update: have you tried ajax with h:commandLink? It would be:
<h:commandButton action="#{hotelscontroller.requestHotelAvail}" value="submit">
<f:ajax render=":rooms"/>
</h:commandButton>
Also I'm not that familiar with primefaces but maybe you can try to explicitly indicate the component to process with additional process="#this" - although I would assume this to be default as in basic library.
You try to inspect the response:
Open Chrome or Firefox -> Inspect Element -> Network and follow the ajax call.