Visualforce provides <apex:include> tag to insert the entire content of a Visualforce page into another page. This is useful mainly when the same content needs to be used in multiple places.Template pages are Visualforce pages that include one or more <apex:insert> components. The <apex:composition> component names the associated template, and provides body for the template’s <apex:insert> components with matching <apex:define> components. Any content outside of an <apex:composition> component is not rendered.
The Example below shows how to use a template with Visualforce using the <apex:include> tag.
Step 1:Create a Visualforce page
ContactList.vfp
<apex:page standardController="Contact" recordSetVar="contacts">
<apex:pageBlock title="Contacts List">
<!-- Contacts List -->
<apex:pageBlockTable value="{! contacts }" var="c">
<apex:column value="{! c.FirstName }"/>
<apex:column value="{! c.LastName }"/>
<apex:column value="{! c.Email }"/>
</apex:pageBlockTable>
</apex:pageBlock>
</apex:page>The Visualforce page uses the StandardsetController to display the Contact details like FirstName, LastName, and Email in a PageBlockTable.
Step 2: Create a Visualforce page using <apex:include>
includetemplate.vfp
<apex:page >
<apex:include pageName="{!$Page.ContactList}"/>
</apex:page>The Visualforce page uses the <apex:include> tag to insert the entire content of the ContactList VF page.
Step 3: Execute the Visualforce page
As the <apex:include> tag is used in the Visualforce page, it displays the list of contacts that are retrieved using the standardsetcontroller in the ContactList VF page .
The example below shows how to use template with a Visualforce using the <apex:insert>,<apex:composition> and <apex:define> tags.
Step 1: Create a Visualforce page using the <apex:insert> tag
insertpage.vfp
<apex:page >
<br><h1 style="color:violet"><apex:insert name="object1"></apex:insert> </h1></br>
<br><h1 style="color:indigo"><apex:insert name="object2"></apex:insert> </h1></br>
<br><h1 style="color:blue"><apex:insert name="object3"></apex:insert> </h1></br>
<br><h1 style="color:green"><apex:insert name="object4"></apex:insert> </h1></br>
<br><h1 style="color:yellow"><apex:insert name="object5"></apex:insert> </h1></br>
<br><h1 style="color:orange"><apex:insert name="object6"></apex:insert> </h1></br>
<br><h1 style="color:red"><apex:insert name="object7"></apex:insert> </h1></br>
</apex:page>The Visualforce page is created with <apex:insert> tag with colors as a style for each tag. If the names of the apex:insert are used in <apex:define>, the styles will be rendered to the content.
Step 2: Create a Visualforce page using the <apex:composition> ,<apex:define> tags.
compositionpage.vfp
<apex:page>
<apex:composition template="{!$Page.insertpage}">
<apex:define name="object1">Campaign</apex:define>
<apex:define name="object2">Lead</apex:define>
<apex:define name="object3">Account</apex:define>
<apex:define name="object4">Contact</apex:define>
<apex:define name="object5">Opportunity</apex:define>
<apex:define name="object6">Contract</apex:define>
<apex:define name="object7">Case</apex:define>
</apex:composition>
</apex:page>The Visualforce page is created with <apex:composition>,<apex:define> and the styles are rendered on the define content by the insert tags from the insertpage VF page.
Step 3: Execute the Visualforce page
The executed Visualforce page shows the content of the <apex:define> tags with the styles used in the <apex:insert> tags in the insertpage.
Reference Link: Visualforce Templates in Salesforce
