Flutter can't seem to find a Json file from relative path - flutter

Question

I apologise in advance if this is a silly question, but I have created a file and stored it in my "assets" sub-directory, which is at the same level as my lib directory and my pubspec.yaml file. I've set the relative path to "assets/ExerData.json" in my code (see below).
When I run the code saved as a scratch.dart file as shown below, hitched up to a Galaxy Nexus API 29 emulator, it can only tell me "Can't find file!"
import 'dart:io';
import 'package:flutter/services.dart';
String filePath = "assets/ExerData.json";
void main() {
performTasks();
}
void performTasks() {
if (checkFileExists(filePath)) {
readFile(filePath);
} else {
print("Can't find file");
}
}
bool checkFileExists(path) {
bool result = File(path).existsSync();
print(result.toString());
return result;
}
Future<String> readFile(path) async {
return await rootBundle.loadString(filePath);
}
I populated my pubspec.yaml file with this entry:
assets:
- assets/ExerData.json
I expected it to find my file, read it using rootbundle.loadstring(path), and print out the resulting string to the console.
As I say, all it did was print "Can't find file".
I'd very much appreciate you help on this one!
Thanks in advance!

Answer 1

The rootBundle contains the resources that were packaged with the app when it was built. All files specified under assets: in your pubspec are packaged with the app. You can check if file exists by wrapping rootBundle.loadString() inside try{} catch(){} block.
Future<bool> fileExists(String path) async {
try {
await rootBundle.loadString(path);
} catch (_) {
return false;
}
return true;
}
or
Future<String?> loadFile(String path) async {
try {
return await rootBundle.loadString(path);
} catch (_) {
// File not found Exception
return null;
}
}
File is a dart class. It needs absolute or relative path of the file being read.
You can use File with path_provider to get the absolute path from the current File System.
For example on Android:
Future<void> getPath() async {
Directory appDocDir = await getApplicationDocumentsDirectory();
String appDocPath = appDocDir.path;
print('PATH IS : $appDocPath');
}
prints
'/data/user/0/com.soliev.file_demo/app_flutter'

Answer 2

Use:
String data = await DefaultAssetBundle.of(context).loadString("assets/ExerData.json");
final jsonResult = jsonDecode(data);
Reference: How to load JSON assets into a Flutter App?

Answer 3

As it turns out, the program logic had not completed initializing the necessary binding.
I called the method WidgetsFlutterBinding.ensureInitialized() in the first line of the main class and everything started working as I expected.
Thanks to everyone who looked at my question!
Here's a similar question involving binding with XML files:
How to read XML files in flutter?