join method

List<Map<String, dynamic>> join(HarnCollection collectionB, String joinField, { List<String> propertiesA = const [], List<String> propertiesB = const [], })

Implementation

List<Map<String, dynamic>> join(HarnCollection collectionB, String joinField,
    {List<String> propertiesA = const [],
    List<String> propertiesB = const []}) {
  final Map<dynamic, List<Map<String, dynamic>>> indexB = {};
  for (final documentB in collectionB.collection.values) {
    final joinValueB = documentB[joinField];
    if (!indexB.containsKey(joinValueB)) {
      indexB[joinValueB] = [];
    }
    indexB[joinValueB]!.add(documentB);
  }

  final List<Map<String, dynamic>> result = [];
  final Map<String, dynamic> joinedDocument = {};
  for (final documentA in collection.values) {
    final joinValueA = documentA[joinField];
    final matchingDocumentsB = indexB[joinValueA];
    if (matchingDocumentsB != null) {
      for (final documentB in matchingDocumentsB) {
        if (propertiesA.isEmpty) {
          joinedDocument.addAll(documentA);
        } else {
          for (int i = 0; i < propertiesA.length; i++) {
            if (documentA.containsKey(propertiesA[i])) {
              joinedDocument[propertiesA[i]] = documentA[propertiesA[i]];
            }
          }
        }
        if (propertiesB.isEmpty) {
          joinedDocument.addAll(documentB);
        } else {
          for (int i = 0; i < propertiesB.length; i++) {
            if (documentB.containsKey(propertiesB[i])) {
              joinedDocument[propertiesB[i]] = documentB[propertiesB[i]];
            }
          }
        }
        result.add(Map.from(joinedDocument));
        joinedDocument.clear();
      }
    }
  }
  return result;
}