How do I save an audio file into Firebase Realtime Database?

Question

I finished setting up my app's functionality to save text-based messages to RTDB (see code below). I now need to be able to save a voice recording that the user records into RTDB. These voice recordings will be interweaved with text-based messages (it's a group chat app), ie users can either send a regular text message or send a voice recording. How do I modify my message model + the code to save a record to RTDB to accomplish this? Is it even possible to save an audio file into RTDB?

message.dart

class Message { //text messages only
  final String uid;
  final String text;
  final DateTime timestamp;
  final String type; 

  Message({
    required this.uid,
    required this.text,
    required this.timestamp,
    required this.type,
  });

  Message.fromJson(Map<dynamic, dynamic>? json): //Transform JSON into Message
        uid = json?['uid'] as String,
        text = json?['text'] as String,
        timestamp = DateTime.parse(json?['timestamp'] as String),
        type = json?['type'] as String;

  Map<dynamic, dynamic> toJson() => <dynamic, dynamic>{ //Transforms Message into JSON
    'uid': uid,
    'text': text,
    'timestamp': timestamp.toString(),
    'type': type,
  };

}

message_dao.dart

class MessageDao {

  MessageDao({required this.groupIDPath}): _messagesRef = FirebaseDatabase.instance.reference().child(groupIDPath);

  String groupIDPath; 
  DatabaseReference _messagesRef;

  //Save a single message to the appropriate node based on groupIDPath
  void saveMessage(Message message) {
    _messagesRef.push().set(message.toJson());
  }
  rest of code...
}

Answer 1

The Firebase Realtime Database can only store JSON types. Storing audio files in the Realtime Database is going to be highly inefficient, as you'd need to convert them to a JSON type (typically base64).

I recommend instead storing the files itself in Cloud Storage, for which there's also a Firebase SDK, and then store a reference to that file (for example its download URL) in the Realtime Database.

To learn more about this, see the documentation onuploading files and getting the download URL .