firebaseflutterdartfirebase-realtime-databasenetwork-connection

Flutter/Firebase realtime database - handle network errors


Firebase realtime database plugin: https://pub.dev/packages/firebase_database

My code to get values from database:

DataSnapshot d = await database.reference().child("my/child/node").once();
Map map = d.value;
String val1 = map["val1"];
String val2 = map["val2"];
String val3 = map["val3"];

It works. However, when there's no network connection, it waits endlessly. I want to catch error (unable to connect to database). Ho do I do that? Try/catch does not work, becasue no exception thrown, it just waits. I want to be informed about database connection error. Is it possible?


Solution

  • You could use a timout like this:

     if (await database
          .reference()
    .child("my/child/node")
        .once()
        .timeout(Duration(seconds: 5), onTimeout: () {
    print('Spent 5 seconds and no connection');
    }).isNotEmpty) {
    print('Connected successfully');
    Map map = d.value;
    String val1 = map["val1"];
    String val2 = map["val2"];
    String val3 = map["val3"];
    }
    

    But you should test it first because i didn't test isNotEmpty function in that case, you should test it and see what dose the line code

    await database
          .reference()
    .child("my/child/node")
        .once()
    

    gives you on successful connection and make the "if" condition as it should. i.e:

      if (await http.get("google.com")
        .timeout(Duration(seconds: 5), onTimeout: () {
    print('Spent 5 seconds and no connection');
    })==200) {
    print('Connected successfully');}
    

    Or you can check for an internet connection before calling the database line. You could use something like this.

       import 'dart:io';
    
    try {
    final result = await InternetAddress.lookup('google.com');
    if (result.isNotEmpty && result[0].rawAddress.isNotEmpty) {
      DataSnapshot d = await database.reference().child("my/child/node").once();
      Map map = d.value;
      String val1 = map["val1"];
      String val2 = map["val2"];
      String val3 = map["val3"];    }
    } on SocketException catch (_) {
    print('not connected');
    }