How to provide path in flutter - path combine

Question

I am creating a quiz app in the Flutter for which I have collected some questions in CSV file. I want to store the CSV file in firebase and display questions into the app by reading from the CSV file. But just to check if the reading file is as simple as it should be, I tried to read a dummy file in this way:

new File('file.txt').readAsString().then((String contents) {
  print(contents);
});

from main.dart before returning the Widget. But i get this error:

`FileSystemException: Cannot open file, path = 'file.txt' (OS Error: No such file or directory, errno = 2)`

even though I have made a dummy 'file.txt' file in the same directory as 'main.dart'.

I tried doing './file.txt' and even the absolute path from windows explorer but none seem to work.

How to fix this?

Answer 1

The path_provider package allows you to access the temp and appDir directory

https://pub.dartlang.org/packages/path_provider

Directory tempDir = await getTemporaryDirectory();
String tempPath = tempDir.path;

Directory appDocDir = await getApplicationDocumentsDirectory();
String appDocPath = appDocDir.path;

You can use the join() method of https://pub.dartlang.org/packages/path to concatenate paths in a platform dependent way, or just use string concatenation like

String filePath = '${appDocDir.path}/file.txt';

new File(filePath).readAsString().then((String contents) {
  print(contents);
});    

Answer 2

You can use join to safely join files or folders:

Example:

import 'package:path/path.dart' as Path;

    String fileName = Path.join('/storage/emulated/0/', '/MyFolder/file.txt');

Result:

fileName = '/storage/emulated/0/MyFolder/file.txt'