Avoiding duplicate ids when reusing facelets compositions in the same naming container

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Depending on the purpose of the <ui:include> template, you’ve several options:

  1. Use <f:subview>. It creates another NamingContainer context (like as <h:form>, <h:dataTable>, and friends all do):

    <f:subview id="top">
    <ui:include src="https://stackoverflow.com/WEB-INF/includes/some.xhtml" />
</f:subview>
...
<f:subview id="bottom">
    <ui:include src="https://stackoverflow.com/WEB-INF/includes/some.xhtml" />
</f:subview>

    The components definied in some.xhtml will end up getting respectively top: and bottom: prefix in their ID.

  2. Turn it into a tagfile which requires an id attribute.

    <my:some id="top" />
...
<my:some id="bottom" />

    And use that ID to prefix the ID of the components in the composition.

    <ui:composition 
    xmlns="http://www.w3.org/1999/xhtml"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:ui="http://java.sun.com/jsf/facelets"
>
    ...
    <h:someComponent id="#{id}_some" />
    <h:otherComponent id="#{id}_other" />
    ...
<ui:composition>

  3. Turn it into a composite component. Composite components are inherently already a NamingContainer, so their id attribute is optional. Basically, replace 

    <ui:composition 
    xmlns="http://www.w3.org/1999/xhtml"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:ui="http://java.sun.com/jsf/facelets"
>
    ...
<ui:composition>

    by

    <ui:component 
    xmlns="http://www.w3.org/1999/xhtml"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:cc="http://java.sun.com/jsf/composite"
>
    <cc:interface>
        <!-- This is optional. -->
    </cc:interface>
    <cc:implementation>
        ...
        <h:someComponent id="some" />
        <h:otherComponent id="other" />
        ...
    </cc:implementation>
<ui:component>

    This way you can use it as follows:

    <my:some id="top" />
...
<my:some id="bottom" />

    The components definied in <cc:implementation> will end up getting respectively top: and bottom: prefix in their ID (note again, the composite component’s id attribute is optional, JSF will otherwise autogenerate one).

See also:

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