Apache FreeMarker extends directive
This repository provides the simple solution.
- copy the following code to
extends.ftl
<#if !blocks??>
<#assign blocks = {} />
</#if>
<#macro extends ftl>
<#nested />
<#include ftl />
</#macro>
<#macro replace name>
<#local value>
<#nested />
</#local>
<#assign blocks += {name: value} />
</#macro>
<#macro block name>
<#if blocks[name]??>
<!-- replaced ${name} -->
${blocks[name]}
<#else>
<!-- default ${name} -->
<#nested />
</#if>
</#macro>
- define your layout as
base.ftl
<#import "extends.ftl" as layout />
<!DOCTYPE html>
<html>
<head>
<title>A demo of FreeMarker extends directive</title>
</head>
<body>
<@layout.block "message">
This is default message in base.ftl
</@layout.block>
</body>
</html>
- extends the layout as
index.ftl
<#import "extends.ftl" as layout />
<@layout.extends "base.ftl">
<@layout.replace "message">
This is the message from index.ftl
</@layout.replace>
</@layout.extends>
That's it.
- extends: extends like Jinja2
- block: block like Jinja2
- replace: replace the block. In Jinja2,
blockdoes this. I tried but it was complicated.
$ ./gradlew run
# run the follow in different shell
$ curl http://localhost:8080/html-freemarker
<!DOCTYPE html>
<html>
<head>
<title>A demo of FreeMarker extends directive</title>
</head>
<body>
<!-- replaced message -->
This is the message from index.ftl
</body>
</html>