I am using the Facelet Templating Technology to layout my page in a JSF 2 app that I am working on.
In my header.xhtml, primefaces requires that menubar be enclosed in h:form.
<h:form>
<p:menubar autoSubmenuDisplay="true">
Menu Items here!
</p:menubar>
</h:form>
So, in my contents pages, I will have another h:form or more.
Will it just work if I just place the h:form in my template.xhtml?
<h:body>
<h:form>
<div id="top">
<ui:insert name="header"><ui:include src="sections/header.xhtml"/></ui:insert>
</div>
<div>
<div id="left">
<ui:insert name="sidebar"><ui:include src="sections/sidebar.xhtml"/></ui:insert>
</div>
<div id="content" class="left_content">
<ui:insert name="content">Content</ui:insert>
</div>
</div>
<div id="bottom">
<ui:insert name="footer"><ui:include src="sections/footer.xhtml"/></ui:insert>
</div>
<h:form>
</h:body>
I am actually thinking of a use case where I need multiple h:form in a page.
Thanks
You can safely use multiple forms in a JSF page. It's not different than when using plain HTML.
Nesting <form> elements is invalid in HTML. Since JSF just generates a bunch of HTML, it's not different in JSF. Nesting <h:form> is therefore also invalid in JSF.
<h:form>
...
<h:form> <!-- This is INVALID! -->
...
</h:form>
...
</h:form>
The browser behavior as to submitting a nested form is unspecified. It may or may not work the way you expect. It may for instance just refresh the page without invoking the bean action method. Even if you move the nested form (or a component that contains it) outside of the parent form with dom manipulation (or by e.g. using the PrimeFaces appendTo="#(body)"), it still won't work and there should be no nested forms at time of loading the page.
As to which forms you need to keep, having a single "god" <h:form> is actually a poor practice. So, you'd best remove the outer <h:form> from the master template and let the header, sidebar, content etc sections each define its own <h:form>. Multiple parallel forms is valid.
<h:form>
...
</h:form>
<h:form> <!-- This is valid. -->
...
</h:form>
Each form must have one clear responsibility. E.g. a login form, a search form, the main form, the dialog form, etc. You don't want to unnecessarily process all other forms/inputs, when you submit a certain form.
Note thus that when you submit a certain form, other forms are NOT processed. So, if you intend to process an input of another form anyway, then you've a design problem. Either put it in the same form or throw in some ugly JavaScript hacks to copy the needed information into a hidden field of the form containing the submit button.
Within a certain form, you can however use ajax to limit the processing of the inputs to a smaller subset. E.g. <f:ajax execute="#this"> will process (submit/convert/validate/invoke) only the current component and not others within the same form. This is usually to be used in use cases wherein other inputs within the same form need to be dynamically filled/rendered/toggled, e.g. dependent dropdown menus, autocomplete lists, selection tables, etc.
See also:
commandButton/commandLink/ajax action/listener method not invoked or input value not set/updated - point 2
What is <f:ajax execute="#all"> really supposed to do? It POSTs only the enclosing form
Understanding PrimeFaces process/update and JSF f:ajax execute/render attributes
<p:commandbutton> action doesn't work inside <p:dialog>
I was confounded by this issue for a while. Instead of a series of independent forms, I converted to a template, that is, rather than making a call to a xhtml with listed forms, usually as ui:include, I make a call to those formerly ui:included xhtml pages that ui:content captured in a parent template.
Related
I have a problem with these two commandButton : Join and Leave.
I want to hide Join if I click on leave and vice-versa.
When I put ajax on false, there is no problem (but all the page is refresh and I don't find this optimal).
But when ajax attribut is on true with specific updating (cf comment in the code), the rendering is good but the new button whitch appear become inactive. If I click on it, nothing happens (well it's seems the actionListener trigger but the view is not refreshed, I have to manual refresh to see the difference)
Thanks for reading.
<h:form id="formWaitingList" rendered="#{connexion.connected}" >
<p:commandButton id="Join"
actionListener = "#{connexion.joinWaitingList()}"
rendered="#{!connexion.waiting}"
ajax="false"
<!-- ajax="true"
update="Join,Leave"-->
value="Join"/>
<p:commandButton id="Leave"
value="Leave"
ajax="false"
<!-- ajax="true"
udpate="Join,Leave"-->
rendered="#{connexion.waiting}"
actionListener ="#{connexion.leaveWaitingList()}" />
</h:form>
It seems that you're not entirely familiar with HTML/JavaScript. You know, JSF is basically a HTML/JavaScript(/CSS) code generator. Ajax updating works basically like this in JavaScript:
After sending the ajax request to JSF via XMLHttpRequest, retrieve a XML response which contains all elements which needs to be updated along with their client IDs.
For every to-be-updated element, use document.getElementById(clientId) to find it in the current HTML DOM tree.
Replace that element by new element as specified in ajax XML response.
However, if a JSF component has not generated its HTML representation because of rendered="false", then there's nothing in the HTML DOM tree which can be found and replaced. That totally explains the symptoms you're "seeing".
You basically need to wrap conditionally rendered JSF components in a component whose HTML representation is always rendered and then reference it instead in the ajax update.
For example,
<h:form>
...
<h:panelGroup id="buttons">
<p:commandButton ... update="buttons" rendered="#{condition}" />
<p:commandButton ... update="buttons" rendered="#{not condition}" />
</h:panelGroup>
</h:form>
See also:
Why do I need to nest a component with rendered="#{some}" in another component when I want to ajax-update it?
In my app I have tutor and student as roles of user. And I decide that main page for both will be the same. But menu will be different for tutors and users. I made to .xhtml page tutorMenu.xhtml and student.xhtml. And want in dependecy from role include menu. For whole page I use layout and just in every page change content "content part" in ui:composition.
In menu.xhtml
<h:body>
<ui:composition>
<div class="menu_header">
<h2>
<h:outputText value="#{msg['menu.title']}" />
</h2>
</div>
<div class="menu_content">
<с:if test="#{authenticationBean.user.role.roleId eq '2'}">
<ui:include src="/pages/content/body/student/studentMenu.xhtml"/>
</с:if>
<с:if test= "#{authenticationBean.user.role.roleId eq '1'}">
<ui:include src="/pages/content/body/tutor/tutorMenu.xhtml" />
</с:if>
</div>
</ui:composition>
I know that using jstl my be not better solution but I can't find other. What is the best decision of my problem?
Using jstl-tags in this case is perfectly fine, since Facelets has a corresponding tag handlers (that are processed in the time of view tree creation) for the jstl tags and handles them perfectly. In this case c:if could prevent processing (and adding the components located in the included xhtml file) of the ui:include which leads to reduced component tree and better performance of the form.
One downside of using this approach is that you cannot update these form parts using ajax, i.e. you change the user role and refresh the form using ajax, because the ui:include for the other role is not part of the view anymore. In such case you have to perform a full page refresh.
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.
This question already has an answer here:
Ajax update/render does not work on a component which has rendered attribute
(1 answer)
Closed 7 years ago.
Hello I have this code to conditionally render components in my page:
<h:commandButton action="#{Bean.method()}" value="Submit">
<f:ajax execute="something" render="one two" />
</h:commandButton>
<p><h:outputFormat rendered="#{Bean.answer=='one'}" id="one" value="#{messages.one}"/></p>
<p><h:outputFormat rendered="#{Bean.answer=='two'}" id="two" value="#{messages.two}"/></p>
It gets the answer and renders the component but in order to see it on my page, I need to refresh the page. How can I fix this problem? Any suggestions?
The JSF component's rendered attribute is a server-side setting which controls whether JSF should generate the desired HTML or not.
The <f:ajax> tag's render attribute should point to a (relative) client ID of the JSF-generated HTML element which JavaScript can grab by document.getElementById() from HTML DOM tree in order to replace its contents on complete of the ajax request.
However, since you're specifying the client ID of a HTML element which is never rendered by JSF (due to rendered being false), JavaScript can't find it in the HTML DOM tree.
You need to wrap it in a container component which is always rendered and thus always available in the HTML DOM tree.
<h:commandButton action="#{Bean.method()}" value="Submit">
<f:ajax execute="something" render="messages" />
</h:commandButton>
<p>
<h:panelGroup id="messages">
<h:outputFormat rendered="#{Bean.answer=='one'}" value="#{messages.one}"/>
<h:outputFormat rendered="#{Bean.answer=='two'}" value="#{messages.two}"/>
</h:panelGroup>
</p>
Unrelated to the concrete problem, you've there a possible design mistake. Why would you not just create a #{Bean.message} property which you set with the desired message in the action method instead, so that you can just use:
<h:commandButton action="#{Bean.method()}" value="Submit">
<f:ajax execute="something" render="message" />
</h:commandButton>
<p>
<h:outputFormat id="message" value="#{Bean.message}" />
</p>
I know it's not the central point of the question, but as I had this problem many times in the past, I just post it here to help others who are in need.
For those who uses PrimeFaces there's a component in PrimeFaces Extension called Switch.
Sometimes you need to display different outputs or components depending on a value. Usually you can achieve this by using the ui:fragment tag. With the pe:switch util tag you won't have to declare ui:fragment tags, with different checks like ui:fragment rendered="#{!empty someController.value}", anymore.
style="visibility: #{questionchoose.show==false ? 'hidden' : 'visible'}"
In a situation where a number of sub-pages will be included using ui:include where should the h:form tag go?
The form should be in the parent (A.xhtml and B.xhtml)?
A.xhtml excerpt
<h:form>
<ui:include src="B.xhtml" />
<ui:include src="other.xhtml" />
</h:form>
B.xhtml exerpt
<ui:composition>
tag contents here
</ui:composition>
The form should be in each child (C.xhtml and D.xhtml)?
C.xhtml excerpt
<ui:include src="D.xhtml" />
<ui:include src="other.xhtml" />
D.xhtml excerpt
<ui:composition>
<h:form>
</h:form>
</ui:composition>
Bonus internet points if you can elaborate on how this works with the Richfaces variation of form and in the first example how regions might be used to isolate each sub-file.
Also, is nesting forms a possibility? It would be like having A.xhtml use D.xhtml.
The first thing is you can't nest forms. Otherwise it depends heavily on your page structure, logic and action buttons/links placement.
When action is triggered it will submit to the server content of the form it is contained in. Therefore it is good when form content corresponds to some business entity which makes sense to be sent together. An extreme approach is to create a single form for the entire page. It will submit all of your inputs at each user interaction. It may make sense in some cases but if your page contains several logically distinct areas I would rather make them into separate forms.
I don't think any extra rules apply when using ui:include, this is one of the possible composition techniques while form layout seems more business structure driven.