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());
Related
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 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());
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');
}
In wp8.0 we can store object to IsolatedStorageSettings. wp8.1 object was not storing. Is there any way to store object to wp8.1.
WRITE OBJECT CODE
NewsList = new ObservableCollection<New>(e.News);
var FileName = "News.xml";
DataContractSerializer serializer = new DataContractSerializer(typeof(ObservableCollection<New>));
var localFolder = ApplicationData.Current.LocalFolder;
var file = await localFolder.CreateFileAsync(FileName,CreationCollisionOption.ReplaceExisting);
IRandomAccessStream sessionRandomAccess = await file.OpenAsync(FileAccessMode.ReadWrite);
IOutputStream sessionOutputStream = sessionRandomAccess.GetOutputStreamAt(0);
serializer.WriteObject(sessionOutputStream.AsStreamForWrite(), NewsList);
READ OBJECT CODE
var FileNameNews = "News.xml";
DataContractSerializer serializer = new DataContractSerializer(typeof(ObservableCollection<New>));
var localFolder = ApplicationData.Current.LocalFolder;
var newsFile = await localFolder.GetFileAsync(FileNameNews);
IInputStream sessionInputStream = await newsFile.OpenReadAsync();
newsVM = new NewsViewModel();
NewsVM.NewsList = (ObservableCollection<New>)serializer.ReadObject(sessionInputStream.AsStreamForRead());
im getting error on this link
IInputStream sessionInputStream = await newsFile.OpenReadAsync();
What mistake is there this code??
Thanks
This is how I do it. No using statements. I try to avoid the Stream syntax as much as possible.
Your error is very likely either because of concurrency (accessing the same file at the same time will throw an exception), or because the stream was not closed properly. I think it is the latter.
You do not dispose of your Stream objects properly (learn the using () {} syntax), which means that the stream remains OPEN after you're done writing. That means you hit the concurrency issue the second time you write, because you're trying to access a stream that's already open.
public async Task CreateOrUpdateData(string key, object o)
{
try
{
if (o != null)
{
var sessionFile = await _localFolder.CreateFileAsync(key, CreationCollisionOption.ReplaceExisting);
var outputString = JToken.FromObject(o).ToString();
await FileIO.WriteTextAsync(sessionFile, outputString);
}
}
catch (Exception e)
{
Debug.WriteLine("Encountered exception: {0}", e);
}
}
public async Task<T> GetDataOrDefault<T>(string key, T defaultValue)
{
try
{
T results = defaultValue;
var sessionFile = await _localFolder.CreateFileAsync(key, CreationCollisionOption.OpenIfExists);
var data = await FileIO.ReadTextAsync(sessionFile);
if (!String.IsNullOrWhiteSpace(data))
{
results = JToken.Parse(data).ToObject<T>();
}
return results;
}
catch (Exception e)
{
Debug.WriteLine("Encountered exception: {0}", e);
}
return defaultValue;
}
I'm newbie on WP8 and trying to build up an app which reads constant variables from XML file and write user changes to another xml file.
However, I failed to create folders or files with following code.
public MainPage()
{
this.InitializeComponent();
this.NavigationCacheMode = NavigationCacheMode.Required;
this.writeFile();
}
public async void writeFile()
{
XDocument xDoc = XDocument.Load("Values.xml");
lblSafakCount.Text = xDoc.Descendants("isFirstUse").FirstOrDefault().Value.ToString();
string input = #"<isFirstUse>NO</isFirstUse>";
var replacement = XElement.Parse(input);;
byte[] bytes = System.Text.Encoding.UTF8.GetBytes(input);
StorageFolder local = ApplicationData.Current.LocalFolder;
if (local != null)
{
StorageFolder sf = await local.CreateFolderAsync("Res", CreationCollisionOption.ReplaceExisting);
StorageFile file = await sf.CreateFileAsync("val.xml", CreationCollisionOption.OpenIfExists);
using (var stream = await file.OpenStreamForWriteAsync())
{
stream.Seek(0, SeekOrigin.End);
stream.Write(bytes, 0, bytes.Length);
}
}
}
I've successfully read isFirstUse parameter from Values.xml so I have no problem with reading from files. When I try to examine codes step by step, app throws no error during the test but not creating folder or file.
Can you please help?
Thanks.
Here are my read and write based on your functions
If you want to write to the SD Card more information can be found here
Access the SD card in Windows Phone
public async void MyWriteFile()
{
string input = #"<isFirstUse>NO</isFirstUse>";
byte[] bytes = System.Text.Encoding.UTF8.GetBytes(input);
StorageFolder local = ApplicationData.Current.LocalFolder;
if (local != null)
{
StorageFolder sf = await local.CreateFolderAsync("Res", CreationCollisionOption.ReplaceExisting);
StorageFile file = await sf.CreateFileAsync("val.xml", CreationCollisionOption.OpenIfExists);
using (var stream = await file.OpenStreamForWriteAsync())
{
stream.Seek(0, SeekOrigin.End);
stream.Write(bytes, 0, bytes.Length);
}
}
}
private async void MyReadFile()
{
byte[] bytes = new byte[256];
StorageFolder local = ApplicationData.Current.LocalFolder;
if (local != null)
{
StorageFolder sf = await local.CreateFolderAsync("Res", CreationCollisionOption.OpenIfExists);
StorageFile file = await sf.CreateFileAsync("val.xml", CreationCollisionOption.OpenIfExists);
using (var stream = await file.OpenStreamForReadAsync())
{
stream.Read(bytes, 0, 256);
}
}
}