Working with XML in Dart and Flutter

Dart offers dart:io package for reading file. To traverse an XML file, we need more than that package.

xml

xml is a Dart library for parsing, traversing, querying, transforming and building XML documents.

var xmlString = '<?xml version="1.0"?>
<root>
  <item>
    <name>Zander Upton</name>
    <info>
      <title>Dr.</title>
      <age>42</age>
      <phone>573.858.4705</phone>
      <email>[email protected]</email>
    </info>
  </item>
  <item>
    <name>Kurtis Maggio</name>
    <info>
      <title>Prof.</title>
      <age>53</age>
      <phone>381-994-9264 x895</phone>
      <email>[email protected]</email>
    </info>
  </item>  
</root>';

//string to XML document
final document = XmlDocument.parse(xmlString);
//convert document to string
var xmlStr = document.toXmlString(pretty: true, indent: '\t');

//traverse
final textual = document.descendants
  .where((node) => node is XmlText && !node.text.trim().isEmpty)
  .join('\n');
print(textual);

//get all item nodes
final items = document.findAllElements('item');

final total = document.findAllElements('item')
    .map((node) => double.parse(node.findElements('age').single.text))
    .reduce((a, b) => a + b);
print(total);

xml_parser

This is an unopinionated XML parser that can read, traverse, and write XML documents.

XmlDocument xmlDocument = XmlDocument.fromString(xmlString);

//get document info
print(xmlDocument.xmlDeclaration.version); 
print(xmlDocument.xmlDeclaration.encoding);
print(xmlDocument.xmlDeclaration.standalone);
print(xmlDocument.doctype.element); 
print(xmlDocument.doctype.externalDtdUri);
print(xmlDocument.root.children.length);

//extract nodes
List<XmlNode> nodes = XmlNode.parseString(
  xmlString,
  returnNodesOfType: <Type>[XmlDeclaration, XmlDoctype, XmlElement],
);

for (XmlNode child in document.children) {
  if (child is XmlDeclaration) {
    print(child.version); // 1.0
  } else if (child is XmlDoctype) {
    print(child.externalDtdName); // rootDtd
  } else if (child is XmlElement) {
    print(child.name); // root
  }
}

xml2json

Like the name suggests, this package convert an XML string to JSON. It supports Badgerfish, GData and Parker conversions.

final converter = Xml2Json();
converter.parse(xmlString); //xmlString is a string in example above

//other conversions
converter.toBadgerfish();
converter.toGData();
converter.toParker();