when I write this code:
onSubmit(){
if(csvname.isEmpty){
print('type name');
}else {
File csvFile = new File(csvname + ".csv");
print('yesssss');
}
}
Does it even create a csv file?
If yes where is it saved or how can I view it?
Full Code / pastebin
It is not saving it with the code you posted, see this doc. Here is an example on how to write to a local file:
Future<String> get _localPath async {
final directory = await getApplicationDocumentsDirectory();
return directory.path;
}
Future<File> get _localFile async {
final path = await _localPath; return File('$path/counter.txt');
}
Future<File> writeCounter(int counter) async {
final file = await _localFile; // Write the file return file.writeAsString('$counter');
}
Related
I'm trying to execute a json file that shows 2 routes with bat files.
To read the file I'm using a path_provider to localize the json file, so that part I have it already done. I need to know why the program can't reconize the text. I put all the information inside a list bc is the correct way to read all the information.
dynamic complete_route = '';
_functionX(String args1, String args2) async {
var shell = Shell();
try {
final dir = await getApplicationDocumentsDirectory();
String d = dir.path;
final path = d;
final route = await ('$path\\config.json');
String contenido = await _leerArchivo(route);
String local_route = complete_route;
shell.run('$local_route $args1 $args2');
} catch (e) {
debug('error', true);
debug(e, true);
}
}
List lista = [];
_leerArchivo(String ruta) async {
try {
//final File f = File(ruta);
final res = await json.decode(ruta);
lista = res["routes"];
complete_route = res.toString();
return lista;
} catch (e) {
return e.toString();
}
}
Add permission in menifest file
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
Put below permission in <application .... /application>
android:requestLegacyExternalStorage="true"
rootBundle is used to access the resources of the application, it cannot be used to access the files in phone storage.
Open the file with
File jsonFile = await File("${dir.path}/demofolder/demo.json");
Then decode this jsonFile using
var jsonData = json.decode(jsonFile.readAsStringSync());
I'm working on a flutter application, and I want to write to a JSON file.
My JSON file is in the 'assets/' folder that I created and added to pubspec.yaml.
I can get the data using :
final String res2 = await rootBundle.loadString("assets/profile.json");
I went through here to get the path to the file: https://docs.flutter.dev/cookbook/persistence/reading-writing-files,
Like this :
Future<File> get _localFile async {
final path = await _localPath;
return File('$path/assets/profile.json');
}
Future<String> get _localPath async {
final directory = await getApplicationDocumentsDirectory();
return directory.path;
}
Future<File> writeJSON(newDatas) async {
final file = await _localFile;
// Write the file
return file.writeAsString('$newDatas');
}
But when I try to access the file, I get this error:
Cannot open file, path = '/data/user/0/com.example.myapp/app_flutter/assets/profile.json'
Do you know why?
Thank you!
I have a Flutter app that has to request a considerable volume of JSON data from the network. This data has to be converted into a Map.
The remote data changes like every week or so, so I am looking for a way to "cache" or permanently store it in order not to have to request it every time the user opens the app.
What would be the best way to achieve this?
If you want to do something quick, you can store that data in a file (source) using path_provider
Create a reference to the file location:
Future<File> get _localFile async {
final path = await getApplicationDocumentsDirectory();
return File('$path/counter.txt');
}
Write data:
Future<File> writeCounter(int counter) async {
final file = await _localFile;
return file.writeAsString('$counter');
}
Read data:
Future<int> readCounter() async {
try {
final file = await _localFile;
final contents = await file.readAsString();
return int.parse(contents);
} catch (e) {
return 0;
}
}
If you want to know all the options you have I suggest you read this: https://flutter.dev/docs/development/data-and-backend/state-mgmt/intro
You can use Hive lib to Save your data
import 'dart:io';
import 'package:hive/hive.dart';
part 'main.g.dart';
#HiveType(typeId: 1)
class Person {
Person({required this.name, required this.age, required this.friends});
#HiveField(0)
String name;
#HiveField(1)
int age;
#HiveField(2)
List<String> friends;
#override
String toString() {
return '$name: $age';
}
}
void main() async {
var path = Directory.current.path;
Hive
..init(path)
..registerAdapter(PersonAdapter());
var box = await Hive.openBox('testBox');
var person = Person(
name: 'Dave',
age: 22,
friends: ['Linda', 'Marc', 'Anne'],
);
await box.put('dave', person);
print(box.get('dave')); // Dave: 22
}
So I have a Flutter app which I'm trying to save some data locally as a JSON file. I'm doing this using dart:convert and jsonEncode and jsonDecode and a Dart Map, but for some reason when I save the Map to a file using file.writeAsString(jsonEncode(map)), it seems to be adding a phantom end bracket to the end like so (not consistently either it doesn't seem):
{
"posts_in_progress":
{
"https://dts.podtrac.com/redirect.mp3/chtbl.com/track/9EE2G/pdst.fm/e/rss.art19.com/episodes/67461d56-cdd8-4b03-a957-3edb110232d4.mp3":73035
}
}
}
This then causes an error when trying to read and decode this file with jsonDecode(file.readAsString()) because of the extra bracket.
What is causing this extra bracket? And how can I prevent this from happening or handle for the extra bracket when its there on the decoding side?
Edit:
LocalServices file which handles all the local data json storage. It doesn't seem to always happen and be easily reproducible, but it has happened multiple times (before I was just handling the local file saving and reading within other methods, but tried to create this local services class to help fix it, still haven't figured out what causes it tho).
import 'dart:convert';
import 'package:path_provider/path_provider.dart';
import 'dart:io';
class LocalService {
bool _isInitialized = false;
Map data;
String filepath;
String filename = 'local_data.json';
File file;
initialize() async {
filepath = await getApplicationDocumentsDirectory().then((directory) => directory.path);
file = await File('$filepath/$filename').exists() ? File('$filepath/$filename') : null;
if(file != null) {
print('Local Data File Exists, start decoding... \n${await file.readAsString()}');
data = jsonDecode(await file.readAsString());
print('Decoding complete!');
} else {
file = new File('$filepath/$filename');
data = new Map<String, dynamic>();
}
_isInitialized = true;
}
update() async {
if(!_isInitialized) {
await this.initialize();
}
try {
data = jsonDecode(await file.readAsString());
} catch (e) {
print('Error Updating file: $e');
}
}
Future<void> setData(String key, dynamic value) async {
if(!_isInitialized) {
await this.initialize();
}
try {
data[key] = value;
await file.writeAsString(jsonEncode(data));
await update();
} catch (e) {
print('Error writing update to file: $e\n$key/$value');
}
}
}
I am trying to read a json file from external Storage (Android). But unable to do it.
I already setup the permission in manifest also checking the permission before reading. Though the file is already in the directory cannot read it.
ModelTestModel modelTestModel;
List<ModelTests> listModelTests;
Future<bool> get readPermission async {
await new Future.delayed(new Duration(seconds: 1));
bool checkResult = await SimplePermissions.checkPermission(
Permission.ReadExternalStorage);
if (!checkResult) {
var status = await SimplePermissions.requestPermission(
Permission.ReadExternalStorage);
if (status == PermissionStatus.authorized) {
var res = await fetchModelTest;
return res != null;
}
} else {
var res = await fetchModelTest;
return res != null;
}
return false;
}
Future<List<ModelTests>> get fetchModelTest async {
var dir = await getExternalStorageDirectory();
print(dir);
final data =
await rootBundle.loadString("${dir.path}/BCS/bsc.json");
print(data);
// var data = await rootBundle.loadString('assets/database/bcs-preparation.json'); this is working when when the file is inside assets
var jsonData = json.decode(data);
modelTestModel = ModelTestModel.fromJson(jsonData);
listModelTests = modelTestModel.modelTests;
return listModelTests;
}
Log
I/SimplePermission(17862): Checking permission :
android.permission.READ_EXTERNAL_STORAGE I/flutter (17862): Directory:
'/storage/emulated/0'
the permission is successful but cannot read the file
rootBundle is used to access the resources of the application, it cannot be used to access the files in phone storage.
Open the file with
File jsonFile = await File("${dir.path}/BCS/bsc.json");
Then decode this jsonFile using
var jsonData = json.decode(jsonFile.readAsStringSync());