Store Firebase Data as JSON locally - firebase

Question

I want to use JSON as a local database for my firebase data ,I don't want offline data store.I am using path_provider to store my data on the phone
So I tried storing data with
file.writeAsStringSync(json.encode(snapshot.toString()))
And it worked the stored data file looked like a JSON file
"{-key:{name:name,age:age},-key:{name:name,age:age}}"
The " " where missing and I can't decode it.
So what can be done here ?
(Edit:Does Firestore provide anything that can help me with this ?)

Answer 1

You can use the shared_preferences package to store JSON,
or if you want to write to a custom file use the path_provider package to get paths to directories where you app has permissions to write to.
You might also need to use the async versions of the dart:io API to access files in Flutter (not sure about that tough)
"{-key:{name:name,age:age},-key:{name:name,age:age}}" is not valid JSON
Either use
import 'dart:convert';
...
var myJson = {'-key':{'name:name','age:age'},'-key':{'name:name','age:age'}}";
var myJsonString = jsonEncode(myJson);
await file.writeAsString(myJsonString);
or
var myJsonString = '{"-key":{"name:name","age:age"},"-key":{"name:name","age:age"}}';
await file.writeAsString(myJsonString);

Answer 2

Create a JSON File
Future<String> get _localPath async {
final directory = await getExternalStorageDirectory();
return directory.path;
}
Future<File> get _dbFile async {
final path = await _localPath;
return new File("$path/demo.json");
}
Write data into a file
Future<File> write(DataSnapshot snapshot,String chatId) async {
final path = await _dbFile;
final String key = snapshot.key;
final String name = snapshot.value['senderUid'];
final int age= snapshot.value['receivedUid'];
String content = '{"$key":{"name":"$name","age":"$age"}}';
return file.writeAsStringSync(content);
}
Read Data
Future<Null> read() async {
try {
final file = await _dbFile;
String content = file.readAsStringSync();
Map<String, dynamic> chatMap=json.decode(content);
chatMap.keys.forEach((E){debugPrint(E);});
} catch (e) {
debugPrint('Error : '+e.toString());
}
}