hi i'm trying to display a tree structure in JSF
for intendation i want to insert
<span class="intendWidth" />
this is my jsf-code
<ui:repeat value="#{myHandler.entityTree}" var="entityDepthHolder">
<p:commandLink action="#{myHandler.toggle(entityDepthHolder.entity)}">
<div>
<c:forEach begin="0" end="#{entityDepthHolder.depth}">
<span class="intendWidth" />
</c:forEach>
#{entityDepthHolder.depth} #{entityDepthHolder.entity.title}
</div>
</p:commandLink>
</ui:repeat>
but for some reason the c:forEach always run once, although only one entityDepthHolder.depth is 1, all others are 0
any ideas how to insert a tag n-times without c:forEach?
The <c:forEach> runs during view build time (that moment when XHTML is turned into JSF component tree), while the <ui:repeat> runs during view render time (that moment when JSF component tree produces HTML output).
So, when the <c:forEach> runs, the #{entityDepthHolder} is nowhere available in the EL scope and evaluates to null and in this case implicitly coerced to 0. As the begin is also 0 and the end is inclusive, you effectively end up with 1 item.
After the view build time, the JSF component tree ends up like this:
<ui:repeat value="#{myHandler.entityTree}" var="entityDepthHolder">
<p:commandLink action="#{myHandler.toggle(entityDepthHolder.entity)}">
<div>
<span class="intendWidth" />
#{entityDepthHolder.depth} #{entityDepthHolder.entity.title}
</div>
</p:commandLink>
</ui:repeat>
And during view render time, the very same HTML is repeatedly generated.
You've 2 options to fix this:
Use <c:forEach> instead of <ui:repeat> on the outer loop. Caveat is, this breaks view scoped beans in Mojarra versions older than 2.1.18.
Use <ui:repeat> instead of <c:forEach> on the inner loop. If you happen to use JSF utility library OmniFaces, then you may find the #{of:createArray()} function helpful in this.
<ui:repeat value="#{of:createArray(entityDepthHolder.depth)}">
See also:
JSTL in JSF2 Facelets... makes sense?
Related
I am trying to conditionally build a custom list using <ui:repeat>. On every occurrence of -1 as item-value in list, I need to add a line break.
I tried to use <c:if> inside <ui:repeat> for that, but it does not seem to work. It always evaluates false.
<ul>
<ui:repeat value="#{topics.list}" var="topicId" >
<li>#{topicId}</li>
<c:if test="#{topicId eq -1}"> <br/> </c:if>
</ui:repeat>
</ul>
Is this possible?
Not with JSTL tags, no. They run during view build time, not during view render time. You can visualize it as follows: when JSF builds the view, JSTL tags run from top to bottom first and the result is a pure JSF component tree. Then when JSF renders the view, JSF components run from top to bottom and the result is a bunch of HTML. So, JSTL and JSF don't run in sync as you'd expect from the coding. At the moment your <c:if> JSTL tag tag runs, the #{topicId} variable which is set by <ui:repeat> JSF component isn't available in the scope.
Instead of using <c:if>, you need to specify the condition in the rendered attribute of the JSF component of interest. As you've actually none, you could wrap it in a <ui:fragment>.
<ul>
<ui:repeat value="#{topics.list}" var="topicId" >
<li>#{topicId}</li>
<ui:fragment rendered="#{topicId eq -1}"><br/></ui:fragment>
</ui:repeat>
</ul>
Alternatives are <h:panelGroup>
<h:panelGroup rendered="#{topicId eq -1}"><br/></h:panelGroup>
or in your specific case <h:outputText escape="false">
<h:outputText value="<br/>" escape="false" rendered="#{topicId eq -1}" />
as both also emits nothing else to the HTML output when no client side attributes are specified.
See also:
JSTL in JSF2 Facelets... makes sense?
Unrelated to the concrete problem, that's the wrong place for a <br/>. It would be ignored by any webbrowser respecting the HTML specification. Don't you mean it to be inside the <li>? Or better, give it a class and let CSS give it a margin-bottom.
I am trying to conditionally build a custom list using <ui:repeat>. On every occurrence of -1 as item-value in list, I need to add a line break.
I tried to use <c:if> inside <ui:repeat> for that, but it does not seem to work. It always evaluates false.
<ul>
<ui:repeat value="#{topics.list}" var="topicId" >
<li>#{topicId}</li>
<c:if test="#{topicId eq -1}"> <br/> </c:if>
</ui:repeat>
</ul>
Is this possible?
Not with JSTL tags, no. They run during view build time, not during view render time. You can visualize it as follows: when JSF builds the view, JSTL tags run from top to bottom first and the result is a pure JSF component tree. Then when JSF renders the view, JSF components run from top to bottom and the result is a bunch of HTML. So, JSTL and JSF don't run in sync as you'd expect from the coding. At the moment your <c:if> JSTL tag tag runs, the #{topicId} variable which is set by <ui:repeat> JSF component isn't available in the scope.
Instead of using <c:if>, you need to specify the condition in the rendered attribute of the JSF component of interest. As you've actually none, you could wrap it in a <ui:fragment>.
<ul>
<ui:repeat value="#{topics.list}" var="topicId" >
<li>#{topicId}</li>
<ui:fragment rendered="#{topicId eq -1}"><br/></ui:fragment>
</ui:repeat>
</ul>
Alternatives are <h:panelGroup>
<h:panelGroup rendered="#{topicId eq -1}"><br/></h:panelGroup>
or in your specific case <h:outputText escape="false">
<h:outputText value="<br/>" escape="false" rendered="#{topicId eq -1}" />
as both also emits nothing else to the HTML output when no client side attributes are specified.
See also:
JSTL in JSF2 Facelets... makes sense?
Unrelated to the concrete problem, that's the wrong place for a <br/>. It would be ignored by any webbrowser respecting the HTML specification. Don't you mean it to be inside the <li>? Or better, give it a class and let CSS give it a margin-bottom.
I'm trying something (JSF2) like this:
<p>#{projectPageBean.availableMethods}</p>
<c:choose>
<c:when test="${projectPageBean.availableMethods == true}">
<p>Abc</p>
</c:when>
<c:otherwise>
<p>Xyz</p>
</c:otherwise>
</c:choose>
But this doesn't seem to work, although the EL expression in the top paragraph changes from false to true, the next paragraph always shows Xyz?
I also tried to change the test to:
${projectPageBean.availableMethods}
But still the same problem!
First and foremost: JSTL tags runs during view build time, not during view render time.
Your concrete problem suggests that #{projectPageBean} is been set during view render time, such as would happen when definied as <ui:repeat var>, <h:dataTable var>, <p:tabView var>, etc. It's thus null during view build time.
In that case, you should not be using a view build time tag to conditionally render HTML. You should instead use a view render time component to conditionally render HTML. As first choice, use <ui:fragment>:
<p>#{projectPageBean.availableMethods}</p>
<ui:fragment rendered="#{projectPageBean.availableMethods}">
<p>Abc</p>
</ui:fragment>
<ui:fragment rendered="#{not projectPageBean.availableMethods}">
<p>Xyz</p>
</ui:fragment>
By the way, there's in Facelets no need to switch between #{} and ${}. In contrary to JSP, in Facelets the ${} behaves exactly the same as #{}. To avoid potential confusion and maintenance trouble, I recommend to stick to #{} all the time.
See also:
Conditional rendering of non-JSF components (plain vanilla HTML and template text)
I'm trying to assign an id to a component inside a <ui:repeat> like that:
<ui:repeat value="#{bean.columns}" var="column">
<h:panelGroup layout="block" id="column_#{column.id}"
styleClass="#{column.id} dashboard_column">
The thing is that #{column.id} value is being placed properly inside the styleClass value but its not being set inside the id attribute. All that is being set inside the id attribute is the automatically generated id by the JSF + my hard coded value column_.
If I remove the hard coded column_ I get an exception:
java.lang.IllegalArgumentException: component identifier must not be a zero-length String
at
Any Ideas?
This is not possible with a render-time tag such as <ui:repeat>. The <ui:repeat> will however by itself already ensure the uniqueness of the generated client ID by prepending it with the row index. So just remove the EL part from the ID attribute of the component.
<ui:repeat value="#{bean.columns}" var="column">
<h:panelGroup layout="block" id="column">
With a view build time tag such as <c:forEach> (which will basically generate multiple <h:panelGroup> components instead of only one which is rendered multiple times), it is possible to specify a dynamic ID like that.
<c:forEach items="#{bean.columns}" var="column">
<h:panelGroup layout="block" id="column_#{column.id}">
(you should only be well aware of how JSTL works in Facelets)
An alternative is to use a static <div> element instead of a JSF <h:panelGroup layout="block"> component.
<ui:repeat value="#{bean.columns}" var="column">
<div id="column_#{column.id}">
See also:
JSTL in JSF2 Facelets... makes sense?
JSF prefixes the id automatically. If you simply write id="column" the generated HTML will contain such identifiers:
myForm:0:column
myForm:1:column
myForm:2:column
and so on.
Anyway: Do never use JSTL tags (like c:foreach and c:if) in JSF templates. They cause random behaviour, very difficult to debug. And if they work, the slow down the application a lot.
Use ui:repeat for loops, and ui:fragment for conditional blocks. Note that there is no replacement for c:set, such a construct does not exist anymore in JSF 2.
I am trying to conditionally build a custom list using <ui:repeat>. On every occurrence of -1 as item-value in list, I need to add a line break.
I tried to use <c:if> inside <ui:repeat> for that, but it does not seem to work. It always evaluates false.
<ul>
<ui:repeat value="#{topics.list}" var="topicId" >
<li>#{topicId}</li>
<c:if test="#{topicId eq -1}"> <br/> </c:if>
</ui:repeat>
</ul>
Is this possible?
Not with JSTL tags, no. They run during view build time, not during view render time. You can visualize it as follows: when JSF builds the view, JSTL tags run from top to bottom first and the result is a pure JSF component tree. Then when JSF renders the view, JSF components run from top to bottom and the result is a bunch of HTML. So, JSTL and JSF don't run in sync as you'd expect from the coding. At the moment your <c:if> JSTL tag tag runs, the #{topicId} variable which is set by <ui:repeat> JSF component isn't available in the scope.
Instead of using <c:if>, you need to specify the condition in the rendered attribute of the JSF component of interest. As you've actually none, you could wrap it in a <ui:fragment>.
<ul>
<ui:repeat value="#{topics.list}" var="topicId" >
<li>#{topicId}</li>
<ui:fragment rendered="#{topicId eq -1}"><br/></ui:fragment>
</ui:repeat>
</ul>
Alternatives are <h:panelGroup>
<h:panelGroup rendered="#{topicId eq -1}"><br/></h:panelGroup>
or in your specific case <h:outputText escape="false">
<h:outputText value="<br/>" escape="false" rendered="#{topicId eq -1}" />
as both also emits nothing else to the HTML output when no client side attributes are specified.
See also:
JSTL in JSF2 Facelets... makes sense?
Unrelated to the concrete problem, that's the wrong place for a <br/>. It would be ignored by any webbrowser respecting the HTML specification. Don't you mean it to be inside the <li>? Or better, give it a class and let CSS give it a margin-bottom.