Windows IoT Raspberry Pi 3 c# Check Folder Exist Create if not - c#

I am trying to check if a folder exist .. if it doesn't i will need to create a folder. My code seems to work if the folder does not exist and create a folder... but subsequently after create the folder.. it runs into exception handler..
I am not sure where went wrong.. please advise.
Thanks.
StorageFolder externalDevices = KnownFolders.RemovableDevices;
IReadOnlyList<StorageFolder> externalDrives = await externalDevices.GetFoldersAsync();
StorageFolder usbStorage = externalDrives[0];
String folderName = "Recordings";
String fileName = DateTime.Now.ToString();
if (!Directory.Exists(folderName))
{
await usbStorage.CreateFolderAsync(folderName);
}
await usbStorage.GetFolderAsync(folderName);
StorageFolder recordFolder = await usbStorage.GetFolderAsync(folderName);
StorageFile recordFile = await recordFolder.CreateFileAsync("Recording -" + DateTime.Now.ToString("yyyy-dd-M--HH-mm-ss") + ".mp3", Windows.Storage.CreationCollisionOption.GenerateUniqueName);
RecordStatus.Text = "File setup OK ... ";

Firstly, using Directory.Exists to check whether a fold exist is not suitable here. The path parameter of Directory.Exists method is permitted to specify relative or absolute path information. Relative path information is interpreted as relative to the current working directory. But in your code, the folderName is not relative to your working directory(in fact,your working directory is Windows.ApplicationModel.Package.Current.InstalledLocation).
Secondly, in UWP, the method of CreateFolderAsync has an overload method with CreationCollisionOption parameter.
Please change this part in your code
if (!Directory.Exists(folderName))
{
await usbStorage.CreateFolderAsync(folderName);
}
To
await usbStorage.CreateFolderAsync(folderName, CreationCollisionOption.OpenIfExists);
It will be ok.

Related

Where are the files created with CreateFileAsync?

When I call the following function, it should create a .txt file and write a sentence in it. It seems to execute without any errors. But I cannot find where this file is stored/located after being created. I ran a Windows Search to look for the file but nothing came up. Where is this file located? Also, what is the best folder/location to put a .txt file that the program uses? Should I put it in Solution Explorer of Visual Studio or Debug folder?
private async void CreateFile() {
try {
// Create sample file, replace if exists.
StorageFolder storageFolder = ApplicationData.Current.LocalFolder;
StorageFile sampleFile = await storageFolder.CreateFileAsync("sample.txt", CreationCollisionOption.ReplaceExisting);
sampleFile = await storageFolder.GetFileAsync("sample.txt");
await FileIO.WriteTextAsync(sampleFile, "Swift as a shadow!");
} catch (Exception ex) {
textBox.Text = ex.ToString();
}
}
You can have the code show the path:
sampleFile = await storageFolder.GetFileAsync("sample.txt");
await new MessageDialog(sampleFile.Path).ShowAsync();
On Windows 10, this will be a path like:
C:\Users\[username]\AppData\Local\Packages\[Package family name]\LocalState\sample.txt
where username is the name of the logged on user and package family name is the package family name of your application

How to add folder to StorageLibrary without RequestAddFolderAsync in C#

I need to save app files to plugged SD card. I'm using UWP and Windows 10.
MSDN tells how to do it with Windows Libraries.
var myPicsLibrary = await Windows.Storage.StorageLibrary.GetLibraryAsync(Windows.Storage.KnownLibraryId.Pictures);
await myPicsLibrary.RequestAddFolderAsync();
RequestAddFolderAsync() shows file picker, where user can choose folder to add into Pictures. In my case it's a folder, created on SD card.
Is there a way to do this thing without file picker dialog?
I'm trying to do like this:
var myPicsLibrary = await Windows.Storage.StorageLibrary.GetLibraryAsync(Windows.Storage.KnownLibraryId.Pictures);
// Get the logical root folder for all external storage devices.
StorageFolder externalDevices = Windows.Storage.KnownFolders.RemovableDevices;
// Get the first child folder, which represents the SD card.
StorageFolder sdCard = (await externalDevices.GetFoldersAsync()).FirstOrDefault();
var folder = await sdCard.CreateFolderAsync("MySDCardFolder");
myPicsLibrary.Folders.Insert(myDocs.Folders.Count+1, folder); // NotImplementedException: 'The method or operation is not implemented.'
myPicsLibrary.Folders.Add(folder); // NotImplementedException: 'The method or operation is not implemented.'
Or maybe I can do the same without using Windows Libraries directly working with SDCard?
Thanks a lot!
EDIT:
In the another hand my question sounds like "How to save files to plugged SD card?"
The StorageLibrary.Folders gets the folders in the current library, it return the IObservableVector of the StorageFolder. When we add the folder into the IObservableVector, it will not change the folder in files system. It will throw the "The method or operation is not implemented." exception.
We should be able to get the name of the folder, and create the folder uses that name. Then we can StorageFile.CopyAsync method to copy the file that in your folder.
For example:
public static async Task CopyFolderAsync(StorageFolder source, StorageFolder destinationContainer, string desiredName = null)
{
StorageFolder destinationFolder = null;
destinationFolder = await destinationContainer.CreateFolderAsync(
desiredName ?? source.Name, CreationCollisionOption.ReplaceExisting);
foreach (var file in await source.GetFilesAsync())
{
await file.CopyAsync(destinationFolder, file.Name, NameCollisionOption.ReplaceExisting);
}
foreach (var folder in await source.GetFoldersAsync())
{
await CopyFolderAsync(folder, destinationFolder);
}
}
Then we can use the CopyFolderAsync method to copy the folder in the Picture Library.
var myPicsLibrary = await Windows.Storage.StorageLibrary.GetLibraryAsync(Windows.Storage.KnownLibraryId.Pictures);
var myfolder = myPicsLibrary.Folders[0];
StorageFolder externalDevices = Windows.Storage.KnownFolders.RemovableDevices;
StorageFolder sdCard = (await externalDevices.GetFoldersAsync()).FirstOrDefault();
var folder = await sdCard.CreateFolderAsync("MySDCardFolder");
await CopyFolderAsync(folder, myfolder);
As I get from your question you need to create a Folder in PicturesLibrary .
You can use the code below to add a folder into PicturesLibrary
await Windows.Storage.KnownFolders.PicturesLibrary.CreateFolderAsync("MySDCardFolder");
if you want to make it on SD Card only Maybe KnownFolders.RemovableDevices Should be helpful . I didn't used KnownFolders.RemovableDevices yet but if you have any issue let me know to test it on my phone directly

UWP Windows 10 C# Writing data to a new line in .txt file [duplicate]

I am looking for a way to append strings-text to a file in a Windows Store App. I have tried reading the file and then creating a new one to overwrite it but Windows Store Apps C# does not work like C where when creating a new file with the same name overwrites the old one. Currently my code is opening the old file, reading it's contents, deleting it and creating a new one with the content I read plus the content I wish to append.
I know there is a better way but I cannot seem to find it. So How may I append text to an already existent file in a Windows Store App (Windows RT)?
EDIT--
I tried this
var folder = Windows.ApplicationModel.Package.Current.InstalledLocation;
var file = await folder.GetFileAsync("feedlist.txt");
await Windows.Storage.FileIO.AppendTextAsync(file, s);
but I keep getting System.UnauthorizedAccessException
according to MSDN this happens when the file is readonly (I checked with right click properties, it's not) and if I do not have the necessary privileges to access the file
what should I do?
You can use the FileIO class to append to a file. For example ...
// Create a file in local storage
var folder = ApplicationData.Current.LocalFolder;
var file = await folder.CreateFileAsync("temp.txt", CreationCollisionOption.FailIfExists);
// Write some content to the file
await FileIO.WriteTextAsync(file, "some contents");
// Append additional content
await FileIO.AppendTextAsync(file, "some more text");
Check out the File Access Sample for more examples.
Using FileIO.AppendTextAsync is a good option.
Please find the code snippet for this.
First it creates a folder, if not exists. Otherwise it will not create.
Then it creates a file if not exists.
Finally appending the text in the file.
public static async void WriteTrace(TraceEventType eventType, string msg, [CallerMemberName] string methodName = "")
{
const string TEXT_FILE_NAME = "Trace.txt";
string logMessage = eventType.ToString() + "\t" + methodName + "\t" + msg ;
IEnumerable<string> lines = new List<string>() { logMessage };
StorageFolder localFolder = ApplicationData.Current.LocalFolder;
StorageFolder tempFolder = ApplicationData.Current.TemporaryFolder;
//if(localFolder.CreateFolderQuery(Windows.Storage.Search.CommonFolderQuery.)
StorageFolder LogFolder = await localFolder.CreateFolderAsync("LogFiles", CreationCollisionOption.OpenIfExists);
await LogFolder.CreateFileAsync(TEXT_FILE_NAME, CreationCollisionOption.OpenIfExists);
StorageFile logFile = await LogFolder.GetFileAsync(TEXT_FILE_NAME);
await FileIO.AppendLinesAsync(logFile, lines);
}

Search files in project folder dynamically

In my Windows Store project I have some .jpg files in my Assets folder. How can I dynamically get all the .jpg files from that folder?
I've tried:
StorageFolder folder = await StorageFolder.GetFolderFromPathAsync("ms-appx:///Assets/");
var fileList = await folder.GetFilesAsync(CommonFileQuery.DefaultQuery);
Must work somehow like this (with a different CommonFileQuery) but this is not working for me. (System Exception at line 1 - wrong path name).
Second question: how do I test if my Assets folder contains "movie.mp4"?
Thank you!
You can use Directory.EnumerateFiles(sourceDirectory, "*.jpg", SearchOption.AllDirectories);
Question 2:
You can use File.Exists(filePath);
Edit
As per your comment, I found this which uses GetFileFromApplicationUriAsync instead of GetFolderFromPathAsync
or
StorageFolder installedLocation = Windows.ApplicationModel.Package.Current.InstalledLocation;
var files = installedLocation.GetFolderFromPathAsync("Assets");
Q2 seems like you can use
TryGetItemAsync
This is the complete solution for my scenario:
Get Files within a project folder of a certain file type.
Check if a file exists within a project folder.
1:
StorageFolder installedLocation = Windows.ApplicationModel.Package.Current.InstalledLocation;
StorageFolder subFolder = await installedLocation.GetFolderAsync("Assets");
subFolder = await subFolder.GetFolderAsync("Images");
List<String> fileType = new List<String>();
fileType.Add(".jpg");
var queryOptions = new QueryOptions(CommonFileQuery.DefaultQuery, fileType);
var query = subFolder.CreateFileQueryWithOptions(queryOptions);
var fileList = await query.GetFilesAsync();
2:
try
{
var video = await subFolder.GetFileAsync("Video.mp4");
}
catch (FileNotFoundException)
{
Debug.WriteLine("No Video found");
}

Appending Text to File Windows store Apps (windows RT)

I am looking for a way to append strings-text to a file in a Windows Store App. I have tried reading the file and then creating a new one to overwrite it but Windows Store Apps C# does not work like C where when creating a new file with the same name overwrites the old one. Currently my code is opening the old file, reading it's contents, deleting it and creating a new one with the content I read plus the content I wish to append.
I know there is a better way but I cannot seem to find it. So How may I append text to an already existent file in a Windows Store App (Windows RT)?
EDIT--
I tried this
var folder = Windows.ApplicationModel.Package.Current.InstalledLocation;
var file = await folder.GetFileAsync("feedlist.txt");
await Windows.Storage.FileIO.AppendTextAsync(file, s);
but I keep getting System.UnauthorizedAccessException
according to MSDN this happens when the file is readonly (I checked with right click properties, it's not) and if I do not have the necessary privileges to access the file
what should I do?
You can use the FileIO class to append to a file. For example ...
// Create a file in local storage
var folder = ApplicationData.Current.LocalFolder;
var file = await folder.CreateFileAsync("temp.txt", CreationCollisionOption.FailIfExists);
// Write some content to the file
await FileIO.WriteTextAsync(file, "some contents");
// Append additional content
await FileIO.AppendTextAsync(file, "some more text");
Check out the File Access Sample for more examples.
Using FileIO.AppendTextAsync is a good option.
Please find the code snippet for this.
First it creates a folder, if not exists. Otherwise it will not create.
Then it creates a file if not exists.
Finally appending the text in the file.
public static async void WriteTrace(TraceEventType eventType, string msg, [CallerMemberName] string methodName = "")
{
const string TEXT_FILE_NAME = "Trace.txt";
string logMessage = eventType.ToString() + "\t" + methodName + "\t" + msg ;
IEnumerable<string> lines = new List<string>() { logMessage };
StorageFolder localFolder = ApplicationData.Current.LocalFolder;
StorageFolder tempFolder = ApplicationData.Current.TemporaryFolder;
//if(localFolder.CreateFolderQuery(Windows.Storage.Search.CommonFolderQuery.)
StorageFolder LogFolder = await localFolder.CreateFolderAsync("LogFiles", CreationCollisionOption.OpenIfExists);
await LogFolder.CreateFileAsync(TEXT_FILE_NAME, CreationCollisionOption.OpenIfExists);
StorageFile logFile = await LogFolder.GetFileAsync(TEXT_FILE_NAME);
await FileIO.AppendLinesAsync(logFile, lines);
}

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