How to read .txt file from assets in Flutter?

Question

I have a .txt file in my folder assets in the Flutter project and when the app is open on a device a SQFlite database is created and should read from this file lines to insert them in the Database. I need to read each line of the .txt file and add them to a List<String> like this :

List<String> _list = await new File('$dir/assets/file.txt').readAsLines();

I have try to use rootBundle but I can't convert the result as a File and by trying to open the file directly like this :

String dir = (await getApplicationDocumentsDirectory()).path;

I always can't find the file and get an error.

var byte = await rootBundle.load('assets/bot.txt'); // Can't convert it to file
String dir = (await getApplicationDocumentsDirectory()).path;
List<String> _list = await new File('$dir/assets/file.txt').readAsLines(); // Error

error FileSystemException: Cannot open file, path = '/data/user/0/com.example.animationexp/app_flutter/assets/file.txt' (OS Error: No such file or directory, errno = 2) during open, closing...

Is there a solution for me to open and read this file ?

Answer 1

It's not working because you just assumed that your assets directory is at ApplicationDocumentsDirectory, then you joined both directories and looked for the file in a path that doesn't exist.

Instead, you should save your file to disk in a known path, and then get the File from that path:

Future<List<String>> getFileLines() async {
  final data = await rootBundle.load('assets/bot.txt');
  final directory = (await getTemporaryDirectory()).path;
  final file = await writeToFile(data, '$directory/bot.txt');
  return await file.readAsLines();
}

Future<File> writeToFile(ByteData data, String path) {
  return File(path).writeAsBytes(data.buffer.asUint8List(
    data.offsetInBytes,
    data.lengthInBytes,
  ));
}

However, if your file is just a simple text file, you should try Julien Lachal's approach. Just keep in mind that rootBundle.loadString() won't work for most file formats.

Answer 2

After having declared the file in pubspec.yml you could simply get the content using:

String fileText = await rootBundle.loadString('assets/file.txt');
print(fileText);