I have another problem to solve. I have a code on my xhtml page:
<t:dataList id="myDataList" value="#{myBean.myList}" var="element" first="0" `rows="10" dir="LTR" frame="hsides" rules="all">`
<c:set target="#{myBean}" property="fid" value="#{element[0]}"/>
...
</t:dataList>
The problem is that value of 'fid' in a bean is null when I`m checking it. When I wrote:
<c:set target="#{myBean}" property="fid" value="8"/>
everything works fine and value is set to '8'. How should i fix this? Thanks for replies.
JSTL tags runs during view build time. JSF tags runs during view render time. You can visualize it as follows: JSTL runs from top to bottom first when the JSF component tree is to be populated, then hands over the component tree to JSF and finally JSF runs from top to bottom to render the HTML.
The element[0] is not there when JSTL is creating the view. It's only there when JSF is rendering the HTML. However, 8 is hardcoded and it is always there.
There are several ways to achieve it the proper way, but since the functional requirement is unclear, I can't suggest a proper approach. Maybe you need f:setPropetyActionListener. Maybe you need DataModel#getRowData() or UIData#getRowData(). Or maybe you don't need it at all.
Related
I have a question about the idea behind the fact, that only UIForm got the attribute prependId. Why is the attribute not specified in the NamingContainer interface? You will now probably say that's because of backward compability but I would preferre breaking the compability and let users which implement that interface, also implement methods for the prependId thing.
The main problem from my perspective about the prependId in the UIForm component is, that it will break findComponent()
I would expect that if I use prependId, then the NamingContainer behaviour would change, not only related to rendering but also when wanting to search for components in the component tree.
Here a simple example:
<h:form id="test" prependId="false">
<h:panelGroup id="group"/>
</h:form>
Now when i want to get the panelGroup component I would expect to pass the string "group" to the method findComponent(), but it won't find anything, I have to use "test:group" instead.
The concrete problem with that is, when using ajax with prependId="false". The ajax tag expects in the attributes update and process, that the values care of naming containers. It's a bit strange that when I use prependId="false" that I have to specify the full id or path, but okay.
<h:form id="test" prependId="false">
<h:panelGroup id="group"/>
</h:form>
<h:form id="test1" prependId="false">
<h:commandButton value="go">
<f:ajax render="test:group"/>
</h:commandButton>
</h:form>
Well this code will render without problems but it won't update the panelGroup because it cannot find it. The PartialViewContext will contain only the id "group" as element of the renderIds. I don't know if this is expected, probably it is but I don't know the code. Now we come to the point where the method findComponent() can not find the component because the expression passed as parameter is "group" where the method would expect "test:group" to find the component.
One solution is to write your own findComponent() which is the way I chose to deal with this problem. In this method i handle a component which is a NamingContainer and has the property prependId set to false like a normal UIComponent. I will have to do that for every UIComponent which offers a prependId attribute and that is bad. Reflection will help to get around the static definition of types but it's still not a really clean solution.
The other way would be introducing the prependId attribute in the NamingContainer interface and change the behaviour of findComponent() to work like described above.
The last proposed solution would be changing the behaviour of the ajax tag to pass the whole id, but this would only solve the ajax issue and not the programmatic issues behind the findComponent() implementation.
What do you think about that and why the hell is it implemented like that? I can't be the first having this problem, but I wasn't able to find related topics?!
Indeed, UIComponent#findComponent() as done by <f:ajax render> fails when using <h:form prependId="false">. This problem is known and is a "Won't fix": JSF spec issue 573.
In my humble opinion, they should never have added the prependId attribute to the UIForm during the JSF 1.2 ages. It was merely done to keep j_security_check users happy who would like to use a JSF form with JSF input components for that (j_security_check requires exact input field names j_username and j_password which couldn't be modified by configuration). But they didn't exactly realize that during JSF 1.2 another improvement was introduced which enables you to just keep using <form> for that instead of sticking to <h:form>. And then CSS/jQuery purists start abusing prependId="false" to avoid escaping the separator character : in their poorly chosen CSS selectors.
Just don't use prependId="false", ever.
For j_security_check, just use <form> or the new Servlet 3.0 HttpServletRequest#login(). See also Performing user authentication in Java EE / JSF using j_security_check.
For CSS selectors, in case you absolutely need an ID selector (and thus not a more reusable class selector), simply wrap the component of interest in a plain HTML <div> or <span>.
See also:
How to select JSF components using jQuery?
How to use JSF generated HTML element ID with colon ":" in CSS selectors?
By default, JSF generates unusable ids, which are incompatible with css part of web standards
I need to complete a xhtml page with some JSF code (with p:panel and p:datatables, etc.) from a managed bean, but I'm not sure that is possible.
My attemps:
1º
<h:outputText escape="true" value="#{controller.jsfString}"/>
It's not be able to understand "p:" components, only simple html.
2º
<ui:include src="#{controller.jsfString}">
It expects a xhtml path, not a String.
I don't know what else try... Is it even possible?
It's not be able to understand "p:" components, only simple html.
Of course it is not!
The h:outputText value is evaluated at view render time, so if you render JSF tags, they won't be evaluated again since rendering is done.
In principle, it could have been possible to add JSF tags this way using the JSTL <c:out>, but it is not available in JSF facelets.
Anyway, just tell yourself that it prevents you from making bad design.
We'll need more information regarding what the controller is supposed to output in order to help you.
Here p means prime-faces u need to include prime-faces dependency in pom and enable tag lib for prime-faces in XHTML then u can use the all the prime-faces components.
I'm currently investigating the performance of a JSF application. I have noticed that code is being executed even though rendered is set to false. For example, take this piece of code:
<h:panelGroup rendered="#{bean.render}">
<my composite component here/>
</h:panelGroup>
Even though #{bean.render} returns false, I can clearly see from debug logs, that the code for my composite component is being executed during the render phase. It also looks like the code is being executed before #{bean.render} is even called. It isn't rendered in the HTML returned to the client, but it still appears that the server is executing the code.
Can anyone explain this?
Thanks.
Composite components are built during render response phase. JSF needs to populate the component tree first and then generate HTML based on the component tree. You're inside the composite component apparently referencing some bean properties which are mandatory to be evaluated during view build time.
If you'd like to conditionally control the building of the composite component instead of the rendering, then you need to use a conditional view build time tag instead of the rendered attribute. JSTL offers the <c:if> and <c:choose> for that.
<c:if test="#{bean.build}">
<my:composite />
</c:if>
See also:
JSTL in JSF2 Facelets... makes sense?
Jsf have to know if your components are rendered or disabled or whatever. Let say you say disabled="false" it is shown on clint side and client may change value and submit the form, even though javascript is disabled by the client, jsf checks it's disabled false or true on server side. if it was true it is not acceptable and never comes to your bean because of process validation phase of jsf, same as rendered="false"
I'm upgrading to JSF 2.0.2 inside Tomcat 7.0.12 and I have a page with a variable number of reusable widgets on it. I used to use t:aliasBean for this purpose, but it doesn't seem to work. I'm now trying the following in my Xhtml:
<c:forEach items="${viewBean.currentView.parts}" var="part">
<t:div styleClass="div#{viewBean.partNumber[part]}">
<c:forEach items="${part.widgets}" var="widget">
<f:subview id="div#{viewBean.widgetId[widget]}">
<ui:include src="widgets/#{widget.widgetPage}">
<ui:param name="widget" value="#{widget}" />
</ui:include>
</f:subview>
</c:forEach>
</t:div>
</c:forEach>
What seems to happen is the next widget from the loop is used in the previous widget's page, so I get errors unless there is only one widget.
Edit: I've tried ui:repeat - it doesn't work. I've also tried removing the ui:include, just as a sanity test; the looping works fine. Also, I'm using Spring 2.5.6.SEC01 - though it shouldn't matter.
I propose to use ui:repeat instead of c:forEach.
Why?
The most important thing to understand
about the jstl tags in Facelets is
that they do not represent components
and never become a part of the
component tree once the view has been
built. Rather, they are tags which are
actually responsible for building the
tree in the first place. Once they
have done their job they expire, are
no more, cease to be, etc etc.
Source [here][1]. I really recommend to read the entire article.
UPDATE:
Please note that I do not say that c:forEach is bad. I want to underline that mixing it with ui:repeat it's not recommended.
[1]: https://rogerkeays.com/jsf-c-foreach-vs-ui-repeat
i have a problem to generate dynamic menu, i'm using JSF1.2. I tried the c:forEach with an arrayList to generate dynamic rich:panelMenu as BalusC advised in a related forum, but get Accessor never triggered in c:forEach. it ruined me a day. can anyone provide me a solution ?
<c:forEach items="#{serviceListBean.services}" var="child">
<rich:panelMenuItem mode="none">
<h:outputText value="#{child.serviceId}"></h:outputText>
</rich:panelMenuItem>
</c:forEach>
what's wrong in this code? can anyone enlighten me?. For info, serviceListBean is request scoped bean.
Two possible causes:
JSTL is not declared as taglib in JSP or Facelets. To confirm this, rightclick page in browser and choose View Source. Do you see <c:forEach> tag unparsed among the generated HTML? If you're using JSP, declare it as follows:
<%#taglib prefic="c" uri="http://java.sun.com/jsp/jstl/core" %>
Or if you're using Facelets, declare it as follows in root element:
xmlns:c="http://java.sun.com/jsp/jstl/core"
On some servers like Tomcat, which doesn't ship with JSTL out the box, you would also need to install JSTL first, see also this info page.
This piece of code is in turn been placed inside a JSF repeating component, like <h:dataTable> with a var="serviceListBean". This is also not going to work. You would need to replace the JSF repeating component by <c:forEach> as well.