Flutter/Dart: return not waiting "toList" with async function to finish-CodePudding

I'm working on an API sync using Flutter and SQFLite.

I get the data from the API, map it, and then add to SQL item by item:

    return (response as List).map((tmp) {
      print('• API: apiSync - Inserting News');
      DBProvider.db.updateNews(ArtNews.fromJson(tmp));
    }).toList();

Everything works fine, but there is a small problem: the return is called before the 'updateNews' is done.

updateNews is a simple async function that writes data on SQFLite.

This creates a big issue: the app opens before the sync is over and data is still being written on DB.

I've tried using AWAIT, but it doesn't make any effect:

   (response as List).map((tmp) async{
      print('• API: apiSync - Inserting $type');
      await DBProvider.db.updateNews(ArtNews.fromJson(tmp));
    }).toList();
    return 'done';

updateNews is called dozens of times, the toList ends, returns 'done', but the updateNews is still adding content to the DB.

I guess there is something I'm missing on toList or async. Any ideas? Thanks!

CodePudding user response：

Try this:

await Future.wait((response as List).map((tmp) {
      print('• API: apiSync - Inserting $type');
      return DBProvider.db.updateNews(ArtNews.fromJson(tmp));
    }));
return 'done';

Gist for reference:

https://dartpad.dev/?id=e72b1dc9013e2add447a90979bed7aab