downloadThumbImage method Null safety

Future<Map> downloadThumbImage(
  1. {@required dynamic target,
  2. @required String? messageId}
)

下载缩略图

@param target 聊天对象， JMSingle | JMGroup | JMChatRoom @param messageId 本地数据库中的消息 id,非 serverMessageId

Implementation

Future<Map> downloadThumbImage({
  @required dynamic target,
  @required String? messageId,
}) async {
  Map param = target.toJson();
  param['messageId'] = messageId;
  Map resJson = await _channel.invokeMethod('downloadThumbImage',
      param..removeWhere((key, value) => value == null));

  return {'messageId': resJson['messageId'], 'filePath': resJson['filePath']};
}