getPart method

MimePart? getPart(String fetchId)

Retrieves the part with the specified fetchId.

Returns null if the part has not been loaded (yet).

Throws a InvalidArgumentException when the fetchId is empty.

Implementation

MimePart? getPart(String fetchId) {
  if (fetchId.isEmpty) {
    throw InvalidArgumentException(
      'Invalid empty fetchId in MimeMessage.getPart(fetchId).',
    );
  }
  final partsByFetchId = _individualParts;
  if (partsByFetchId != null) {
    final part = partsByFetchId[fetchId];
    if (part != null) {
      return part;
    }
  }
  final idParts = fetchId.split('.').map<int?>(int.tryParse);
  MimePart parent = this;
  var warningGiven = false;
  for (final id in idParts) {
    if (id == null) {
      if (!warningGiven) {
        print('Warning: unable to retrieve individual parts from '
            'fetchId [$fetchId] (in MimeMessage.getPart(fetchId)).');
        warningGiven = true;
      }
      continue;
    }
    final parts = parent.parts;
    if (parts == null || parts.length < id) {
      // this mime message is not fully loaded
      return null;
    }
    parent = parts[id - 1];
  }

  return parent;
}