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

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!

CodePudding user response：

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;
  }

  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'

CodePudding user response：

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?