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How to check if file exist after saved it?

I'm working in a UWP app, at some point, the user has the chance to save an image (done) by now I only let the user know that the save operation was done by a "messageDialog", this is my code:
var savePicker = new Windows.Storage.Pickers.FileSavePicker();
savePicker.SuggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.DocumentsLibrary;
savePicker.FileTypeChoices.Add("QR Code", new List<string>() { ".png", ".jpg", ".jpeg", ".jpe", ".bmp" });
savePicker.SuggestedFileName = "QR_01";
Windows.Storage.StorageFile file = await savePicker.PickSaveFileAsync();
if (file != null)
{
Windows.Storage.CachedFileManager.DeferUpdates(file);
await Windows.Storage.FileIO.WriteBytesAsync(file, _bytes3);
Windows.Storage.Provider.FileUpdateStatus status = await Windows.Storage.CachedFileManager.CompleteUpdatesAsync(file);
if (status == Windows.Storage.Provider.FileUpdateStatus.Complete)
{
var messageDialog = new Windows.UI.Popups.MessageDialog("File saved on: " + file.Path);
await messageDialog.ShowAsync();
}
else
{
//this.textBlock.Text = "File " + file.Name + " couldn't be saved."; not defined by now
}
done = true;
}
else
{
this.textBlock.Text = "operation canceled";
done = false;
}
This works good so far but I want to be sure that the file is already there after the "WriteBytesAsync" method. So, this is the thing, the users can save the image in any directory they have acces to so I can't check (or read) the folder they choose afer that because I don't have acces permission afer save the file. I have tryed something like this to get folder access:
string savePath = System.IO.Path.GetDirectoryName(file.Path);
Windows.Storage.StorageFolder saveFolder = await Windows.Storage.StorageFolder.GetFolderFromPathAsync(savePath);
In order to use the "GetFileAsync" to check the file or the "FutureAccessList" for a future access but since I have file access permisions to any directory it fails, and because of that I can't use any of the solution in here: UWP Check If File Exists
My Questions are:
1.- Is there a way to check if the file was saved or successfully written afer the user click the "Save" button?
2.- Does the "WriteBytesAsync" method is enough to ensure taht the file was saved?? according to the info FileIO.WriteBytesAsync(IStorageFile, Byte[]) Method, it don't throw any exception.

but I want to be sure that the file is already there after the "WriteBytesAsync" method.
For you requirement, you could use GetFileFromPathAsync method to get the file, if the file is not null, means that the file is exist. And please note if you want to above method, you need add broadFileSystemAccess capability, and open it in your system setting. For more please refer this.
Windows.Storage.CachedFileManager.DeferUpdates(file);
await Windows.Storage.FileIO.WriteBytesAsync(file, new byte[3]);
var temp = await StorageFile.GetFileFromPathAsync(file.Path);
if(temp != null)
{
}
else
{
}
Does the "WriteBytesAsync" method is enough to ensure taht the file was saved??
Yep, WriteBytesAsync method need to pass StorageFile parameter. if the file parameter is not null means it has created in the folder. Or it will throw null exception.

How can I open a .pdf file in the browser from a Xamarin UWP project?

I have a Xamarin Project where I generate a .pdf file from scratch and save it in my local storage. This works perfectly fine and can find it and open it in the disk where I saved it. However, I need to open the .pdf file immediately after creation programmatically.
I already tried different variations using Process and ProcessStartInfo but these just throw errors like "System.ComponentModel.Win32Exception: 'The system cannot find the file specified'" and "'System.PlatformNotSupportedException'".
This is basically the path I am trying to open using Process.
var p = Process.Start(#"cmd.exe", "/c start " + #"P:\\Receiving inspection\\Inspection Reports\\" + timestamp + ".pdf");
I also tried ProcessStartInfo using some variations but I'm getting the same errors all over and over.
var p = new Process();
p.StartInfo = new ProcessStartInfo(#"'P:\\Receiving inspection\\Inspection Reports\\'" + timestamp + ".pdf");
p.Start();

The better way is that use LaunchFileAsync method to open file with browser. You could create FileLauncher DependencyService to invoke uwp LaunchFileAsync method from xamarin share project.
Interface
public interface IFileLauncher
{
Task<bool> LaunchFileAsync(string uri);
}
Implementation
[assembly: Dependency(typeof(UWPFileLauncher))]
namespace App14.UWP
{
public class UWPFileLauncher : IFileLauncher
{
public async Task<bool> LaunchFileAsync(string uri)
{
var file = await Windows.Storage.StorageFile.GetFileFromPathAsync(uri);
bool success = false;
if (file != null)
{
// Set the option to show the picker
var options = new Windows.System.LauncherOptions();
options.DisplayApplicationPicker = true;
// Launch the retrieved file
success = await Windows.System.Launcher.LaunchFileAsync(file, options);
if (success)
{
// File launched
}
else
{
// File launch failed
}
}
else
{
// Could not
}
return success;
}
}
}
Usage
private async void Button_Clicked(object sender, EventArgs e)
{
await DependencyService.Get<IFileLauncher>().LaunchFileAsync("D:\\Key.pdf");
}
Please note if you want to access D or C disk in uwp, you need add broadFileSystemAccess capability. for more please refer this .
Update
If the UWP files are network based, not local zone based, you could use Xamarin.Essentials to open file with browser. And you must specify the privateNetworkClientServer capability in the manifest. For more please refer this link.

Google Firebase and Unity (C#): Unable to download png from bucket

Specs
Unity editor version: 2018.2.8f1
Firebase Unity SDK version: 5.5.0
Additional SDKs: SimpleFirebaseUnity
Developing on: Mac
Export Platform: Android
Issue
I'm having troubles setting up a system to download pictures from storage. I'm not an expert in databases, but I wanted to give it try, just to learn how it is done.
I found Firebase very useful to store metadata on the real-time database and easy to approach even for an entry level programmer like me.
The problem is that I'm trying to download a .png file from a folder in storage, but I can't manage to find if the file is actually downloaded or if it's just lost in the process. I don't get any errors in the console, but when I open the folder in which the files should be, it's empty.
Code
private SimpleFirebaseUnity.Firebase firebaseDatabase;
private FirebaseQueue firebaseQueue;
private FirebaseStorage firebaseStorage;
private StorageReference m_storage_ref;
// Setup refernece to database and storage
void SetupReferences()
{
// Get a reference to the database service, using SimpleFirebase plugin
firebaseDatabase = SimpleFirebaseUnity.Firebase.CreateNew(FIREBASE_LINK, FIREBASE_SECRET);
// Get a reference to the storage service, using the default Firebase App
firebaseStorage = FirebaseStorage.DefaultInstance;
// Create a storage reference from our storage service
m_storage_ref = firebaseStorage.GetReferenceFromUrl(STORAGE_LINK);
// Create a queue, using SimpleFirebase
firebaseQueue = new FirebaseQueue(true, 3, 1f);
}
// ...
IEnumerator DownloadImage(string address, string fileName)
{
var local_path = Application.persistentDataPath + THUMBNAILS_PATH;
var content_ref = m_storage_ref.Child(THUMBNAILS_PATH + fileName + ".png");
content_ref.GetFileAsync(local_path).ContinueWith(task => {
if (!task.IsFaulted && !task.IsCanceled)
{
Debug.Log("File downloaded.");
}
});
yield return null;
}

There can be many reason for why this is not working for you including:
security rules are not setup properly
paths to files are not correct
you are testing it on wrong platform (Firebase is not working well in the editor)
your device is blocking the connection
etc...
In order to get error messages you need to log them:
IEnumerator DownloadImage(string address, string fileName)
{
var local_path = Application.persistentDataPath + THUMBNAILS_PATH;
var content_ref = m_storage_ref.Child(THUMBNAILS_PATH + fileName + ".png");
content_ref.GetFileAsync(local_path).ContinueWith(task => {
if (!task.IsFaulted && !task.IsCanceled)
{
Debug.Log("File downloaded.");
}
else
{
Debug.Log(task.Exception.ToString());
}
});
yield return null;
}
Keep in mind testing it in the editor may not work.

Get all files inside a specific folder in a library with UWP

I'm trying to get all the videos in a specific folder inside the Videos library using UWP, right now I can get all videos inside the Videos library, but I'd like to reduce my results to only those inside the specified folder. My code is this:
Windows.Storage.Search.QueryOptions queryOption = new QueryOptions(CommonFileQuery.OrderByTitle, new string[] {".mp4"});
queryOption.FolderDepth = FolderDepth.Deep;
var files = await KnownFolders.VideosLibrary.CreateFileQueryWithOptions(queryOption).GetFilesAsync();
StorageFile videoToPlay = (files[new Random().Next(0, files.Count)] as StorageFile);
var stream = await videoToPlay.OpenAsync(Windows.Storage.FileAccessMode.Read);
Player.SetSource(stream, videoToPlay.ContentType);
Debug.WriteLine(Player.Source);
How could I access a subfolder named "Videos to Play" and then get all the videos inside that folder? I tried accesing it by using a path like:
string localfolder = Windows.Storage.ApplicationData.Current.LocalFolder.Path;
var array = localfolder.Split('\\');
var username = array[2];
string[] allVideos = System.IO.Directory.GetFiles("C:/Users/" + username + "/Videos/Videos to Play");
But I get access denied even though I already requested access to the Videos library (and the fact that the first example works shows that I actually have access to it).

try
{
var folder = await KnownFolders.VideosLibrary.GetFolderAsync("Videos to Play");
}
catch (FileNotFoundException exc)
{
// TODO: Handle the case when the folder wasn't found on the user's machine.
}
In the folder variable you'll have the reference to the desired folder. Then it's the very same stuff that you already do, but instead of KnownFolders.VideosLibrary folder use this one!

How to check if a file exist in windowsstore app [duplicate]

This question already has answers here:
How to check if file exists in a Windows Store App?
(10 answers)
Closed 9 years ago.
While making a lab on window 8 app dev. I could not load all images needed. So inorder for the share part to work with a sharing imag I need to check if the image file is availeble.
The project is a windows grid app using XAML and C#
In the past I used
Using System.IO
... lost of code
privat void share()
....
if (File.exist(filename)
{
add file to share
}
If i try this in my window8 project. The File class is not found.
I search the internet but could not find a code example that checkes the existance in a windowsstore app in C#
Michiel

you need StorageFile not File
here is simple example to check and get the file
StorageFile file;
try {
file = await ApplicationData.Current.LocalFolder.GetFileAsync("foo.txt");
}
catch (FileNotFoundException) {
file = null;
}
you can write a function
public static async Task<bool> FileExistsAsync(this StorageFolder folder, string fileName)
{
try
{
await folder.GetFileAsync(fileName);
return true;
}
catch (FileNotFoundException)
{
return false;
}
}

If you know the path in your local storage and you have a bunch of files to check, you can do the following...
var sourceFolder = Windows.ApplicationModel.Package.Current.InstalledLocation;
sourceFolder = await sourceFolder.GetFolderAsync("Assets");
var files = await sourceFolder.GetFilesAsync();
var requiredFiles = new List<String> { "ThisWorks.png", "NotHere.png" };
foreach(var filename in requiredFiles)
{
// your example logic here...
Debug.WriteLine(filename + " " + (files.Any(f => f.Name == filename) ? "Exists" : "Doesn't exist"));
}