Скачать или смотреть Mastering Apache Freemarker: How to Display Repeating XML Nodes with Child Elements

Learn how to effectively parse XML structures using Apache Freemarker and XPath to display nodes and their child elements dynamically.
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This video is based on the question https://stackoverflow.com/q/63078623/ asked by the user 'Jestino Sam' ( https://stackoverflow.com/u/6389283/ ) and on the answer https://stackoverflow.com/a/63079254/ provided by the user 'Jack Fleeting' ( https://stackoverflow.com/u/9448090/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Mastering Apache Freemarker: How to Display Repeating XML Nodes with Child Elements

When working with XML data, it is common to face challenges while trying to extract and present information dynamically. If you are using Apache Freemarker for templating, you may find yourself needing to parse XML structures effectively using XPath expressions. This guide will walk you through a particular problem: displaying repeating nodes along with their child nodes in an organized manner.

The Problem

Imagine you have the following XML structure that represents a book with chapters and paragraphs:

[[See Video to Reveal this Text or Code Snippet]]

You want to display the chapters and their corresponding paragraphs in a neat format. Your desired output should look like this:

[[See Video to Reveal this Text or Code Snippet]]

However, you might encounter issues when trying to achieve this using XPath in Freemarker.

The Solution

To get the desired output, you need to use nested lists in Freemarker. Here’s how you can do it:

Step-by-Step Guide

Parse the chapter Nodes: Start by iterating over each chapter element in your XML document.

Access the Child Elements: For each chapter, you will then need to loop through each para element.

Example Code Snippet

Here’s the Freemarker template code that accomplishes this:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

<# list xml["//chapter"] as t>: This line initializes a loop through each chapter node in your XML.

${t.title}: This outputs the title of the chapter.

<# list t[".//para"] as p>: Inside the first loop, this initializes a nested loop to iterate over all child para nodes for the current chapter.

${p}: This prints each paragraph within the current chapter.

By organizing your code this way, Freemarker is able to dynamically display each chapter and its child paragraphs as specified.

Final Thoughts

Using Apache Freemarker to parse XML with XPath can be straightforward when you understand how to utilize nested lists effectively. This method not only simplifies the process, but it also ensures that your output is consistently formatted and easy to read.

Whether you are developing web applications, generating reports, or just need to display structured data from XML, knowing how to manipulate these structures is vital.

Happy coding!