Adding default files to local storage in Flutter - flutter

Question

TLDR: I understand how to create a new file via Dart and path provider, but I don't know how to get a pre-existing file into the Android/Apple file system.
I'm building this app which works a bit with string manipulation. Ideally, I want it reading strings from a pre-existing CSV file which I'm getting from a client, then manipulating the data to create more CSV files. I found packages for both CSV and Paths. What I don't know is how to get my CSV in there.
As of now I have this file called test.csv in my app's root directory. I tried to access it through my main.dart by using File f = File("$_localPath/test.csv"). The file was nowhere to be found. I then went into the phone's memory using Android Studio, and found the local storage path of the app. My test.csv file was nowhere to be seen. My guess right now is that at compilation, that CSV file becomes garbage machine code. So how can I get it intact into the device's local memory?
I don't want to get the file from the internet because I'm hoping the user can boot up the app for the first time in any setting and be able to have its full functionality.

Answer 1

I just tested this code example and it works on all platforms.
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatefulWidget {
const MyApp({super.key});
#override
State<MyApp> createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
String _fileContent = '';
final TextEditingController _controller = TextEditingController();
#override
initState() {
super.initState();
WidgetsBinding.instance.addPostFrameCallback((_) {
readFile();
});
}
Future<String> getFilePath() async {
Directory appDocumentsDirectory =
await getApplicationDocumentsDirectory(); // 1
String appDocumentsPath = appDocumentsDirectory.path;
String filePath = '$appDocumentsPath/file.csv';
return filePath;
}
void saveFile() async {
File file = File(await getFilePath());
if (mounted) {
file.writeAsString(_controller.text);
setState(() {
_fileContent = _controller.text;
});
_controller.text = '';
}
}
void readFile() async {
File file = File(await getFilePath());
final fileContent = await file.readAsString();
if (mounted) {
setState(() {
_fileContent = fileContent;
});
}
}
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(title: const Text('Saving CSV file')),
body: Padding(
padding: const EdgeInsets.all(16),
child: Column(
children: [
Text('Current content = $_fileContent'),
TextField(
controller: _controller,
),
TextButton(
onPressed: saveFile,
child: const Text('Press to save file'),
),
],
),
),
),
);
}
}
This code creates the file and sets a content into it. Then, after restarting the app, it tries to find the file and receive its content. After that it shows the content inside a Text widget.
I used this article for making this example. Hope it will help:)