Setting <f:param> value with <ui:repeat> var - jsf

<h:form>
<ui:repeat value="#{sampleManagedBean.food}" var="food">
<h:commandLink value="Name" action="#{sampleManagedBean.outcome}">
<f:param name="name" value="ssd" />
<f:param name="v" value="#{food.boy}" />
</h:commandLink>
<h2>#{food.boy}</h2>
</ui:repeat>
</h:form>
I can't get the the second <f:param> value which is set based on <ui:repeat var>. I can get only the first one which is hardcoded.

The ui:repeat is an UI component while f:param is a taghandler (like JSTL). Taghandlers run during view build time before UI components which run during view render time
(see here).
In our case it means that in the view build phase f:param knows nothing about #{food.boy}. c:forEach will be fine, but if we call some kind of ajax action to change the size of#{sampleManagedBean.food} and rerender the form, we'll not see any changes on page. Because partial rerendering (ajax) affects only UI component tree. c:forEach is somewhere between hardcoding and ui:repeat, we'll have to reload the page to see changes.

try this way,
<h:form>
<ui:repeat value="#{sampleManagedBean.food}" var="food">
<h:commandLink value="Name" action="#{sampleManagedBean.outcome}">
<f:setPropertyActionListener value="ssd" target="#{sampleManagedBean.name}" />
<f:setPropertyActionListener value="#{food.boy}" target="#{sampleManagedBean.v}" />
</h:commandLink>
</ui:repeat>
</h:form>

Related

index of ui:repeat is empty [duplicate]

I have following code:
<ui:repeat var="class2" value="#{bean.list}" varStatus="status">
<h:form id="#{class2.name}">
<h:outputText value="#{class2.name}" />
</h:form>
</ui:repeat>
However, when I open the page, it errors as follows:
component identifier must not be a zero-length String
But it is properly printed in the <h:outputText>. How is this caused and how can I solve it?
You can use EL in the id attribute of a JSF component, but the EL variable has to be available during view build time, while the JSF component tree is to be built. However, the <ui:repeat> runs during view render time, while the HTML output is to be generated based on JSF component tree. The <ui:repeat var> is not available during view build time and #{class2.name} evaluates to null which totally explains the error you got. That it works in <h:outputText> is because it runs during view render time.
If you replace <ui:repeat> by <c:forEach>, which runs during view build time, then it'll work as you intented. The <c:forEach> will namely generate physically multiple <h:form> components in the JSF component tree which each generate individually their own HTML output (in contrary to <ui:repeat>, wherein the very same <h:form> component is been reused multiple times to generate HTML output).
<c:forEach var="class2" items="#{bean.list}" varStatus="status">
<h:form id="#{class2.name}">
<h:outputText value="#{class2.name}" />
</h:form>
</c:forEach>
However, I really wonder why you need to do that. There's usually no need to dynamically assign component IDs. JSF will already ensure the uniqueness of the ID. The below example,
<ui:repeat var="class2" value="#{bean.list}" varStatus="status">
<h:form id="form">
<h:outputText value="#{class2.name}" />
</h:form>
</ui:repeat>
will end up in multiple forms with each an unique ID, suffixed with iteration index of the <ui:repeat>. If you actually need to use #{class2.name} for some JavaScript/jQuery purposes (you did nowhere state the concrete functional requirement in the question for which you thought that this would be the right solution, so it's merely guessing), then just wrap it in a plain vanilla HTML element:
<ui:repeat var="class2" value="#{bean.list}" varStatus="status">
<div id="#{class2.name}">
<h:form id="form">
<h:outputText value="#{class2.name}" />
</h:form>
</div>
</ui:repeat>
Or set it as style class of a JSF component, which is also just selectable via a CSS selector:
<ui:repeat var="class2" value="#{bean.list}" varStatus="status">
<h:form id="form" styleClass="#{class2.name}">
<h:outputText value="#{class2.name}" />
</h:form>
</ui:repeat>
See also:
JSTL in JSF2 Facelets... makes sense?

JSF rendered method is not invoked in the second time

I have next a4j:jsFunction
<a4j:jsFunction name="renderOnBusinessErrorEvent" execute="#none" bypassUpdates="true" immediate="true"
render="securityForm">
</a4j:jsFunction>
and JSF form with some dialog inside
<h:form id="securityForm">
<h:panelGroup rendered="#{someCondition}">
......
</h:panelGroup>
</h:form>
In my business logic it has to be executed twice consequently. In the first time all is fine. Rendered method is invoked and the expected dialog is present on the page. In the second time rendered method is not invoked, but model has been changed and I expect that dialog will not be present on the page. I supposed that it's some richfaces issue and I tried to use f:ajax
<a4j:jsFunction name="renderOnBusinessErrorEvent" execute="#none" bypassUpdates="true" immediate="true">
<f:ajax event="begin" render=":securityForm"/>
</a4j:jsFunction>
but unsuccessfully. Rendered method still not invoked in the second time. What is it? Some JSF optimization or bug? What's the workaround?
JSF version 2.1.19
The problem was in <h:panelGroup rendered="#{someOtherCondition}">
over h:form which equals false after the first rendering (ON THE SERVER SIDE).
However, this panelGroup is not part of rendering. So, my code:
<h:panelGroup rendered="#{someOtherCondition}">
<h:form id="securityForm">
<h:panelGroup rendered="#{someCondition}">
......
</h:panelGroup>
</h:form>
</h:panelGroup>
<h:form>
<a4j:jsFunction name="renderOnBusinessErrorEvent" execute="#none" bypassUpdates="true" immediate="true"
render="securityForm">
</a4j:jsFunction>
</h:form>
Before calling renderOnBusinessErrorEvent() I'm changing the value of someOtherCondition from true to false, but I don't rerender this element. Actually, on the server side this element is already missing. Looks like it's JSF feature, but is it specificated somewhere?

Why JSF composite component doesn't work inside a ui:repeat? [duplicate]

I have following code:
<ui:repeat var="class2" value="#{bean.list}" varStatus="status">
<h:form id="#{class2.name}">
<h:outputText value="#{class2.name}" />
</h:form>
</ui:repeat>
However, when I open the page, it errors as follows:
component identifier must not be a zero-length String
But it is properly printed in the <h:outputText>. How is this caused and how can I solve it?
You can use EL in the id attribute of a JSF component, but the EL variable has to be available during view build time, while the JSF component tree is to be built. However, the <ui:repeat> runs during view render time, while the HTML output is to be generated based on JSF component tree. The <ui:repeat var> is not available during view build time and #{class2.name} evaluates to null which totally explains the error you got. That it works in <h:outputText> is because it runs during view render time.
If you replace <ui:repeat> by <c:forEach>, which runs during view build time, then it'll work as you intented. The <c:forEach> will namely generate physically multiple <h:form> components in the JSF component tree which each generate individually their own HTML output (in contrary to <ui:repeat>, wherein the very same <h:form> component is been reused multiple times to generate HTML output).
<c:forEach var="class2" items="#{bean.list}" varStatus="status">
<h:form id="#{class2.name}">
<h:outputText value="#{class2.name}" />
</h:form>
</c:forEach>
However, I really wonder why you need to do that. There's usually no need to dynamically assign component IDs. JSF will already ensure the uniqueness of the ID. The below example,
<ui:repeat var="class2" value="#{bean.list}" varStatus="status">
<h:form id="form">
<h:outputText value="#{class2.name}" />
</h:form>
</ui:repeat>
will end up in multiple forms with each an unique ID, suffixed with iteration index of the <ui:repeat>. If you actually need to use #{class2.name} for some JavaScript/jQuery purposes (you did nowhere state the concrete functional requirement in the question for which you thought that this would be the right solution, so it's merely guessing), then just wrap it in a plain vanilla HTML element:
<ui:repeat var="class2" value="#{bean.list}" varStatus="status">
<div id="#{class2.name}">
<h:form id="form">
<h:outputText value="#{class2.name}" />
</h:form>
</div>
</ui:repeat>
Or set it as style class of a JSF component, which is also just selectable via a CSS selector:
<ui:repeat var="class2" value="#{bean.list}" varStatus="status">
<h:form id="form" styleClass="#{class2.name}">
<h:outputText value="#{class2.name}" />
</h:form>
</ui:repeat>
See also:
JSTL in JSF2 Facelets... makes sense?

Why doesn't h:commandButton execute the action method when combined with c:chose?

I've seen a strange problem in my project. It's that <h:commandButton/> does not execute the action method.
<c:choose>
<c:when test="#{empty param.t}">
// HTML
</c:when>
<c:when test="#{param.t eq 'normal'}">
// HTML
<h:form>
<h:commandButton value="ADD" action="#{addBean.doSomething}" />
</h:form>
<c:when>
</c:choose>
When I move <h:form> into first c:when, then the action method is called. Otherwise, it isn't. Why?
I'll ignore the syntax error in your EL (a missing }).
The command button won't be executed when #{param.t eq 'normal'} evaluates to false at the point the form submit request is to be processed. You need to maintain the same parameter for the subsequent request so that the button will be rendered so that JSF can confirm that the enduser is allowed to invoke the action. You can do this by adding a <f:param>:
<h:form>
<h:commandButton value="ADD" action="#{addBean.doSomething}">
<f:param name="t" value="#{param.t}" />
</h:commandButton>
</h:form>
Note that this is supported since JSF 2.0 only. On JSF 1.x you'd need to replace h:commandButton by a h:commandLink if you want f:param support.
Unrelated to the concrete problem, you should try to avoid JSTL as much as possible in your JSF views. If the intent is to render view parts conditionally (not to build view parts conditionally), then you should rather be using the JSF component's rendered attribute instead of a JSTL <c:choose> or <c:if>:
<h:panelGroup rendered="#{empty param.t}">
// HTML
</h:panelGroup>
<h:panelGroup rendered="#{param.t eq 'normal'}">
// HTML
<h:form>
<h:commandButton value="ADD" action="#{addBean.doSomething}" />
</h:form>
</h:panelGroup>

why composite compoment does not invoke in the <h:datatable/>

I have a compoment which has a method-signature attribute. It can be activated, but if I put it in a <h:datatable> <h:column/> and trigger this component, it does not work.
When I just refresh this page again or when I put it in another place it can invoked successfully. I would be grateful if somebody can tell me why!
this is my code
<h:column>
<f:facet name="header">op:</f:facet>
<h:commandLink value="alter" action="#{userSession.alterAction}"
rendered="#{userSession.user.power.powerID == 1}">
<f:param name="beanId" value="#{book.bookID}" />
<f:param name="class" value="#{BookBean}" />
</h:commandLink>
<h:commandLink action="#{userSession.detailAction}" value="detail"
rendered="#{userSession.user != null}">
<f:param name="beanId" value="#{book.bookID}" />
<f:param name="class" value="#{BookBean}" />
</h:commandLink>
<h:commandLink action="#{bookAction.bookDelAction}"
onclick="return confirm('are you sure?')" value="delete"
rendered="#{userSession.user.power.powerID == 1}">
<f:param name="beanId" value="#{book.bookID}" />
</h:commandLink>
</h:column>
this manageredBean #{bookAction} is requestScope when i click one of this operation,just like delete ,it doesnot work at all. but if i put the 'delete' commandlink out of <h:datatabel/> .it can invoke backing method successfully. it is so upset!
who can tell me whether <h:datatable/> can Shielding the .i found if i put these code in a <h:form/> .it can invoke too! cound you can tell me the reason!
You need to preserve exactly the same data model (i.e. the one which you have referenced by the value attribute of the <h:dataTable>) in during the request of the form submit as it was during the request of displaying the initial form. The symptoms indicate that you're using a request scoped bean and that the loading of the data model is based on some request parameter which is missing during the form submit and/or the loading is not being done during bean's (post)construction.
Putting the bean in the view scope and/or rearranging the data loading logic should fix it.

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