generateForAnnotatedElement method

@override Future<String> generateForAnnotatedElement(Element element, ConstantReader annotation, BuildStep buildStep)

Implement to return source code to generate for element.

This method is invoked based on finding elements annotated with an instance of T. The annotation is provided as a ConstantReader.

Supported return values include a single String or multiple String instances within an Iterable or Stream. It is also valid to return a Future of String, Iterable, or Stream.

Implementations should return null when no content is generated. Empty or whitespace-only String instances are also ignored.

Implementation

@override
Future<String> generateForAnnotatedElement(
  Element element,
  ConstantReader annotation,
  BuildStep buildStep,
) async {
  final objectName = element.name;

  final jsonFilePath = annotation.read('file').stringValue;
  final jsonFileUri = Uri(path: jsonFilePath);

  final jsonAsset = AssetId.resolve(jsonFileUri, from: buildStep.inputId);
  final contents = await buildStep.readAsString(jsonAsset);

  final mergeStrategy = MergeStrategy.nonMatchingToDynamic;
  final decoded = json.decode(contents);

  final dataType = JsonToDataTypeConverter.convert(decoded);

  if (dataType is! ObjectType) {
    // TODO: Handle this exception more gracefully
    throw Exception('JSON file does not contain an object.');
  }

  final result = DartCodeGenerator.generateCodeForObject(
    dataType,
    mergeStrategy: mergeStrategy,
    className: objectName,
  );

  return result;
}