How do I conditionally render a <ui:define>?
The data in the template depends on a required <f:viewParam>.
But if an invalid view parameter is provided, then the <ui:define> should not be rendered since the default content of the template should be used.
I tried using <c:if> but it is not working.
It's not possible to conditionally render/build an <ui:define>. You can only do for its contents. Anything outside <ui:define> is ignored in templates.
Better is to conditionally build the <ui:insert> instead. The <ui:insert> runs during view build time, so it's not possible to conditionally render it by a property which is set via <f:viewParam>. You can only conditionally build it (the <ui:insert> tag itself) using a conditional view build time tag such as JSTL <c:if> which in turn checks the raw request parameter directly (and thus not the <f:viewParam> property).
In the master template, it would look like this, assuming that just the sole presence of the request parameter is sufficient (if you need to perform validation, you'd need to do it inside the EL expression, or in a managed bean wherein the property is preinitialized via #ManagedProperty("#{param.foo}").
E.g., in the master template:
<c:if test="#{not empty param.foo}">
<ui:insert name="content" />
</c:if>
<c:if test="#{empty param.foo}">
<p>Default content</p>
</c:if>
or, more clear but more verbose
<c:choose>
<c:when test="#{not empty param.foo}">
<ui:insert name="content" />
</c:when>
<c:otherwise>
<p>Default content</p>
</c:otherwise>
</c:choose>
See also:
JSTL in JSF2 Facelets... makes sense?
Use <ui:fragment> instead.
<ui:define name="description">
<ui:fragment rendered="false">
<meta name="description" content="do not render" />
</ui:fragment>
</ui:define>
Duplicate of ui:define with rendered="false" attribute still rendering
Related
I am wondering which is more effective/readable etc for jsf, conditionally including or deciding inside the include whether to render the content.
e.g. conditional include
<h:panelGroup rendered="#{entitiy.condition}">
<ui:include src="included.xml">
<ui:param name="entity" value="#{entity}" />
</ui:include>
</h:panelGroup>
vs always include
<ui:include src="included.xml" />
<ui:param name="entity" value="#{entity}" />
</ui:include>
and then inside included.xml:
<h:panelGroup rendered="#{entity.condition}">
<h:outputText value="#{entity.name}" />
</h:panelGroup>
IMHO conditional include feels more natural:
if condition then
do something
I am not sure if this is really better but use c:if for the check as this would totally remove the code evaluation. See JSTL in JSF2 Facelets... makes sense?
h:panelGroup adds a span while c:if is pure render logic.
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 want to update an ui:param value or use something similar in ui:repeat loops with a condition. The idea is something as follows (is just an aprox, not the final implementation but I guess is understandable):
<ui:param name="marginLeftNode" value="#{myBean.initialMarginValue}" />
<ui:repeat value="#{myBean.viewWrapper.linkMap.entrySet().toArray()}" var="map">
<ui:repeat var="link" value="#{map.value}" varStatus="status">
<li style="margin-left: #{marginLeftNode}%" class="ico-#{link.getStyleCss()}-ayuda">
#{link.getTitle()}
</li>
<!-- Code conditions that doesn't works in any way as I've readed in the links after code -->
<c:if test="#{marginLeftNode gt 4}">
<ui:param name="marginLeftNode" value="#{myBean.viewWrapper.nodeList.get(status.index).depth}" />
</c:if>
<ui:fragment rendered="#{marginLeftNode gt 4}">
<ui:param name="marginLeftNode" value="#{myBean.viewWrapper.nodeList.get(status.index).depth}" />
</ui:fragment>
<!-- End code conditions: these are the two solutions c:if and ui:fragmen I tried -->
</ui:repeat>
</ui:repeat>
I can't use c:if inside ui:repeat because doesn't works (Specify conditional rendering of element inside <ui:repeat>? The <c:if> does not seem to work) and I can't use ui:fragment with ui:param because it doesn't works too (Conditional variable definition in JSF)
So, any idea how to solve that?
First of all, avoid of use JSTL if you can use JSF. Here is an answer that explains how JSTL and JSF are executed in different steps -> https://stackoverflow.com/a/3343681/4253629
To redefine conditionally a ui:param, for example, you can do this:
<ui:param
name="marginLeftNode"
value="#{marginLeftNode gt 4 ? myBean.viewWrapper.nodeList.get(status.index).depth : marginLeftNode }"/>
Probably exists another solution, but this works.
Greetings
Changing the ui:param inside the loop has no real value. The real purpose of a ui:param is to pass runtime variables into a template client or included file. By the time your parameter has been passed in, there's little value in changing it. If all you want is to conditionally alter the value of the variable after it's been passed, you could just use JSTL's c:set to set a page-scoped variable that you could then use
<ui:repeat value="#{myBean.viewWrapper.linkMap.entrySet().toArray()}" var="map">
<ui:repeat var="link" value="#{map.value}" varStatus="status">
<li style="margin-left: #{marginLeftNode}%" class="ico-#{link.getStyleCss()}-ayuda">
#{link.getTitle()}
</li>
<c:if test="#{marginLeftNode gt 4}">
<c:set var="marginLeftNode" value="#{myBean.viewWrapper.nodeList.get(status.index).depth}"/>
</c:if>
</ui:repeat>
You could then access your set variable as #{marginLeftNode} anywhere within that view
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.