Dart XML: A Lightweight and Feature-Rich XML Library for Dart

Dart XML is a robust library for working with XML documents in Dart. It offers a DOM-based object model for manipulating and querying XML documents, as well as an event-driven API for incremental reading and processing of XML streams.

Installation and Usage

To install Dart XML, follow the instructions on dart packages: https://pub.dev/packages/xml/install

Import the library into your Dart code:

import 'package:xml/xml.dart';

Reading and Writing XML

Reading XML

final bookshelfXml = '''<?xml version="1.0"?>
<bookshelf>
<book>
<title lang="en">Growing a Language</title>
<price>29.99</price>
</book>
<book>
<title lang="en">Learning XML</title>
<price>39.95</price>
</book>
<price>132.00</price>
</bookshelf>''';
final document = XmlDocument.parse(bookshelfXml);

Writing XML

print(document.toString());
print(document.toXmlString(pretty: true, indent: '\t'));

Traversing and Querying XML

Traversing XML

document.children; // direct children of the root element
document.descendants; // all descendants of the root element
document.preceding; // nodes preceding the opening tag of the current node

Querying XML

document.findAllElements('title'); // find all elements with the 'title' tag
document.xpath('/bookshelf/book[2]'); // find the second book element

Building XML

Using the Builder Pattern

final builder = XmlBuilder();
builder.element('bookshelf', nest: () {
  builder.element('book', nest: () {
    builder.element('title', nest: () {
      builder.attribute('lang', 'en');
      builder.text('Growing a Language');
    });
    builder.element('price', nest: 29.99);
  });
  builder.element('book', nest: () {
    builder.element('title', nest: () {
      builder.attribute('lang', 'en');
      builder.text('Learning XML');
    });
    builder.element('price', nest: 39.95);
  });
  builder.element('price', nest: 132.00);
});
final document = builder.buildDocument();

Event-Driven Processing

Dart XML provides an event-based API for incremental reading and processing of XML streams.

Using Iterables

parseEvents(bookshelfXml)
  .whereType<XmlTextEvent>()
  .map((event) => event.value.trim())
  .where((text) => text.isNotEmpty)
  .forEach(print);

Using Streams

final url = Uri.parse('http://ip-api.com/xml/');
final request = await HttpClient().getUrl(url);
final response = await request.close();
await response
  .transform(utf8.decoder)
  .toXmlEvents()
  .normalizeEvents()
  .forEachEvent(onText: (event) => print(event.value));

Conclusion

Dart XML is a powerful and well-supported library for working with XML documents in Dart. Its extensive feature set and simple API make it a valuable tool for data parsing, transformation, and building.