How to intertwine Async functions and sync functions in flutter

Question

I am a beginner to flutter and I don't quite understand how to use Async functions in flutter. For example,

Future <String> readData() async {
  final file = await localFile;
  String body = await file.readAsString();
  return body;
}

So in this code, I retrieve some data from a local file. But I want to run this function at the start of the app and want to display the result.

Unfortunately, my build function in main.dart is a synchronous one and when I do:

child : Text(readData());

It does not work due to the fact that it returns a Future . I can't use the await keyword either because it Build is not async. How do I go about waiting to get this string and display it?

dangngocduc · Accepted Answer · 2020-06-01 14:18:23Z

1

You can try using FutureBuilder

  child: FutureBuilder<String>(
      builder: (context, data) {
        return Text(data.hasData ? data.data : '');
      },
      future: readData(),
  ),

edited Jun 1, 2020 at 14:18

answered Jun 1, 2020 at 14:08

dangngocduc

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1 Comment

dangngocduc Over a year ago

You can also using a variable in State of StatefullWidget and setState when file.readAsString() completed.

Ricky · Accepted Answer · 2020-06-01 14:14:02Z

0

Dart Streams - Flutter in Focus

This is very well explained I think should help you

answered Jun 1, 2020 at 14:14

Ricky

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1 Comment

Devoloper Over a year ago

Thanks for this, can you give me some context in terms of code as to what I can do?

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