How to conditionally render plain HTML elements like <div>s?

https://stackoverflow.com/questions/8816813

15-04-2021
|

سؤال

I'm trying to implement a composite component which either displays the information details of a user in plain text or displays them through editable input texts fields if the desired details are those of the user currently connected.

I know that al UI Components can be rendered via the rendered attribute but what about the ones which are not UI Components (for example divs)

<div class = "userDetails" rendered = "#{cc.attrs.value.id != sessionController.authUser.id}">
    Name: #{cc.attrs.value.name}
    Details: #{cc.attrs.value.details}
</div>

<div class = "userDetails" rendered = "#{cc.attrs.value.id == sessionController.authUser.id}">
    <h:form>
        ...
    </h:form>
</div>

I know that the div doesn't have the rendered attribute and probably I'm not taknig the right approach at all. I could very easily use an JSTL tag but I want to avoid that.

المحلول

The right JSF component to represent a HTML <div> element is the <h:panelGroup> with the layout attribute set to block. So, this should do:

<h:panelGroup layout="block" ... rendered="#{someCondition}">
    ...
</h:panelGroup>

Alternatively, wrap it in an <ui:fragment>:

<ui:fragment rendered="#{someCondition}">
    <div>
        ...
    </div>
</ui:fragment>

Or when you're already on JSF 2.2+, make it a passthrough element:

<div jsf:rendered="#{someCondition}">

</div>

Do note that when you'd like to ajax-update a conditionally rendered component, then you should be ajax-updating its parent component instead.

<h:panelGroup rendered = "#{cc.attrs.value.id != sessionController.authUser.id}">
    <div class = "userDetails">
        Name: #{cc.attrs.value.name}
        Details: #{cc.attrs.value.details}
    </div>
</h:panelGroup>

<h:panelGroup  rendered = "#{cc.attrs.value.id == sessionController.authUser.id}">
    <div class = "userDetails">
        <h:form>
           ...
        </h:form>
    </div>
</h:panelGroup>

Another option is to use components from either Seam (<s:div>) or Tomahawk (<t:htmlTag>) libraries if you already have them in your project.

See: http://www.jsftoolbox.com/documentation/seam/09-TagReference/seam-div.html

<s:div styleClass = "userDetails" rendered = "#{cc.attrs.value.id != sessionController.authUser.id}">
    Name: #{cc.attrs.value.name}
    Details: #{cc.attrs.value.details}
</s:div>

<s:div styleClass = "userDetails" rendered = "#{cc.attrs.value.id == sessionController.authUser.id}">
    <h:form>
        ...
    </h:form>
</s:div>

Or: http://myfaces.apache.org/tomahawk-project/tomahawk12/tagdoc/t_htmlTag.html

<t:htmlTag value="div" styleClass = "userDetails" rendered = "#{cc.attrs.value.id != sessionController.authUser.id}">
    Name: #{cc.attrs.value.name}
    Details: #{cc.attrs.value.details}
</t:htmlTag>

<t:htmlTag value="div" styleClass = "userDetails" rendered = "#{cc.attrs.value.id == sessionController.authUser.id}">
    <h:form>
        ...
    </h:form>
</t:htmlTag>

You could use another composite components. There are no divs or other additional tags, just exactly the one you need. See this example:

<table>
    <tr>...</tr>
    <my:cc rendered="false">
        <tr>...</tr>
    </my:cc>
    <my:cc rendered="true">
        <tr>...</tr>
    </my:cc>
</table>

And the my:cc component:

<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:cc="http://xmlns.jcp.org/jsf/composite">

    <cc:interface>
    </cc:interface>

    <cc:implementation>
        <cc:insertChildren />
    </cc:implementation>
</html>

Produces following HTML, no additional tags at all, working with ajax.

<table><tr>...</tr><tr>...</tr></table>

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How to conditionally render plain HTML elements like <div>s?

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