Mastering YAML Parsing with the Dart Library

YAML (YAML Ain't Markup Language) is a widely used data serialization format in various fields. The Dart programming language offers a robust library for parsing YAML documents, enabling efficient processing of YAML data.

Parsing YAML with loadYaml

To parse a single YAML document, use the loadYaml method. Here's an example:

import 'package:yaml/yaml.dart';

void main() {
  var doc = loadYaml("YAML: YAML Ain't Markup Language");
  print(doc['YAML']); // Prints "YAML Ain't Markup Language"
}

loadYaml takes a string representing the YAML document as input and returns a Map, List, or primitive value based on the document's structure.

Parsing YAML Streams with loadYamlStream

YAML documents can also be present as a stream of multiple documents. To parse a stream of documents, use the loadYamlStream method.

import 'package:yaml/yaml.dart';

void main() {
  var stream = loadYamlStream("document1:\n  prop1: 10\ndocument2:\n  prop2: 20");
  for (var document in stream) {
    print(document);
  }
}

loadYamlStream takes a string containing multiple YAML documents and returns an Iterable of Map, List, or primitive values representing each document.

Dumping to YAML

Although the Dart YAML library does not currently support dumping to YAML, you can use the json.encode method from the dart:convert library as a workaround.

import 'dart:convert';
import 'package:yaml/yaml.dart';

void main() {
  var doc = loadYaml("YAML: YAML Ain't Markup Language");
  print(json.encode(doc)); // Prints "{\"YAML\": \"YAML Ain't Markup Language\"}"
}

This workaround allows you to convert YAML data to JSON, which can then be used for various purposes such as serialization or storage.

Conclusion

The Dart YAML library provides a straightforward and efficient way to parse YAML documents and streams. By leveraging the loadYaml and loadYamlStream methods, you can easily extract data from YAML sources. While dumping to YAML is not directly supported, the workaround using json.encode offers a viable solution for converting YAML data to JSON for further processing or storage.