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Read file right after it was created and closed [duplicate]

This question already has answers here:
File being used by another process after using File.Create()
(11 answers)
Closed 1 year ago.
After creating a file via File.Create, I want to read it afterwards with File.ReadAllText. However, I always get an exception that says that the process cannot access the file. Once the file is created, access works without problems.
So I assume that the file is not yet released by File.Create at the time where it should be read. How do I solve this? Below is my method.
public SettingsModel LoadSettings()
{
var _fullPath = FileHelper.GetFullPath(_fileName);
if (!File.Exists(_fullPath))
{
File.Create(_fullPath).Close();
}
var serializedSettings = File.ReadAllText(_fullPath);
var settings = JsonConvert.DeserializeObject<SettingsModel>(serializedSettings);
if (settings == null)
{
return new SettingsModel();
}
else
{
return settings;
}
}

You create an empty file to deserialize it afterwards. You can perform deserialization only if the file exists:
public SettingsModel LoadSettings()
{
var _fullPath = FileHelper.GetFullPath(_fileName);
var settings = File.Exists(_fullPath)
? JsonConvert.DeserializeObject<SettingsModel>(File.ReadAllText(_fullPath))
: new SettingsModel();
return settings;
}

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.

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!

UWP Check If File Exists

I am currently working on a Windows 10 UWP App.
The App needs to Check if a certain PDF File exists called "01-introduction", and if so open it.
I already have the code for if the file does not exist.
The Code Below is what i currently have:
try
{
var test = await DownloadsFolder.CreateFileAsync("01-Introduction.pdf", CreationCollisionOption.FailIfExists);
}
catch
{
}
This code Does not work correctly because to check if the file exists here, I attempt to create the file. However if the file does not already exist an empty file will be created. I do not want to create anything if the file does not exist, just open the PDF if it does.
If possible, i would like to look inside a folder which is in the downloads folder called "My Manuals".
Any help would be greatly appreciated.

public async Task<bool> IsFilePresent(string fileName)
{
var item = await ApplicationData.Current.LocalFolder.TryGetItemAsync(fileName);
return item != null;
}
But not support Win8/WP8.1
https://blogs.msdn.microsoft.com/shashankyerramilli/2014/02/17/check-if-a-file-exists-in-windows-phone-8-and-winrt-without-exception/

There are two methods
1) You can use StorageFolder.GetFileAsync() as this is also supported by Windows 8.1 and WP 8.1 devices.
try
{
StorageFile file = await DownloadsFolder.GetFileAsync("01-Introduction.pdf");
}
catch
{
Debug.WriteLine("File does not exits");
}
2) Or you can use FileInfo.Exists only supported for windows 10 UWP.
FileInfo fInfo = new FileInfo("01-Introduction.pdf");
if (!fInfo.Exists)
{
Debug.WriteLine("File does not exits");
}

System.IO.File.Exists is UWP way too. I test now in Windows IOT. it just works.

This helped me in my case:
ApplicationData.Current.LocalFolder.GetFileAsync(path).AsTask().ContinueWith(item => {
if (item.IsFaulted)
return; // file not found
else { /* process file here */ }
});

This worked for me running my UWP C# app on Windows 10...
StorageFolder app_StorageFolder = await StorageFolder.GetFolderFromPathAsync( #App.STORAGE_FOLDER_PATH );
var item = await app_StorageFolder.TryGetItemAsync(relative_file_pathname);
return item != null;

public override bool Exists(string filePath)
{
try
{
string path = Path.GetDirectoryName(filePath);
var fileName = Path.GetFileName(filePath);
StorageFolder accessFolder = StorageFolder.GetFolderFromPathAsync(path).AsTask().GetAwaiter().GetResult();
StorageFile file = accessFolder.GetFileAsync(fileName).AsTask().GetAwaiter().GetResult();
return file != null;
}
catch
{
return false;
}
}

You can use System.IO.File.
Example:
// If file located in local folder. You can do the same for other locations.
string rootPath = ApplicationData.Current.LocalFolder.Path;
string filePath = Path.Combine(rootPath, "fileName.pdf");
if (System.IO.File.Exists(filePath))
{
// File exists
}
else
{
// File doesn't exist
}

I'm doing a Win10 IoT Core UWP app and I have to check the file length instead of "Exists" because CreateFileAsync() already creates an empty file stub immediately. But I need that call before to determine the whole path the file will be located at.
So it's:
var destinationFile = await ApplicationData.Current.LocalFolder.CreateFileAsync("MyFile.wow", ...);
if (new FileInfo(destinationFile.Path).Length > 0)
return destinationFile.Path;

In this way System.IO.File.Exists(filePath) I cannot test DocumentLibrary
because KnownFolders.DocumentsLibrary.Path return empty string
Next solution is very slow await DownloadsFolder.GetFileAsync("01-Introduction.pdf")
IMHO the best way is collect all files from folder and check the file name exist.
List<StorageFile> storageFileList = new List<StorageFile>();
storageFileList.AddRange(await KnownFolders.DocumentsLibrary.GetFilesAsync(CommonFileQuery.OrderByName));
bool fileExist = storageFileList.Any(x => x.Name == "01-Introduction.pdf");

CreateFileSync exposes an overload that let's you choose what to do if an existing file with the same name has been found in the directory, as such:
StorageFile localDbFile = await DownloadsFolder.CreateFileAsync(LocalDbName, CreationCollisionOption.OpenIfExists);
CreationCollisionOption is the object that you need to set up. In my example i'm opening the file instead of creating a new one.

Based on another answer here, I like
public static async Task<bool> DoesFileExist(string filePath) {
var directoryPath = System.IO.Path.GetDirectoryName(filePath);
var fileName = System.IO.Path.GetFileName(filePath);
var folder = await StorageFolder.GetFolderFromPathAsync(directoryPath);
var file = await folder.TryGetItemAsync(fileName);
return file != null;
}

You can use the FileInfo class in this case. It has a method called FileInfo.Exists() which returns a bool result
https://msdn.microsoft.com/en-us/library/system.io.fileinfo.exists(v=vs.110).aspx
EDIT:
If you want to check for the files existence, you will need to create a StorageFile object and call one of the GetFile.... methods. Such as:
StorageFile file = new StorageFile();
file.GetFileFromPathAsync("Insert path")
if(file == null)
{
/// File doesn't exist
}
I had a quick look to find the download folder path but no joy, but the GetFile method should give you the answer your looking for

On Window 10, for me, this is the most "elegant" way:
private static bool IsFileExistent(StorageFile file)
{
return File.Exists(Path.Combine(file.Path));
}
Or, as an extension if you prefer and will use it widely:
static class Extensions
{
public static bool Exists(this StorageFile file)
{
return File.Exists(Path.Combine(file.Path));
}
}

Copy a file in a new folder

I have a problem coping a file. I need to copy a .db file and put it in a new folder (called "directory",selected previously with FolderPicker).
The code that i have is: (this is for a store app for Windows 8.1)
try{
StorageFile newDB = await StorageFile.GetFileFromPathAsync(directory);
StorageFile originalDB = await StorageFile.GetFileFromPathAsync(Path.Combine(Windows.Storage.ApplicationData.Current.LocalFolder.Path, "AFBIT.db"));
await newDB.CopyAndReplaceAsync(originalDB);
}
catch(Exception ex){
}
I have a exception in neDB, and said "Value does not fall within the expected range."
I dont know another way to copy a file in xaml, if u know what is the problem or another way to do this i llbe very grateful.

I have something similar that I currently use when copying a file CopyFileAsync method I have created see if this can help you in regards to refactoring your code to a working model
public static async Task CopyFileAsync(string sourcePath, string destinationPath)
{
try
{
using (Stream source = File.Open(sourcePath, FileMode.Open))
{
using (Stream destination = File.Create(destinationPath))
{
await source.CopyToAsync(destination);
}
}
}
catch (IOException io)
{
HttpContext.Current.Response.Write(io.Message); //I use this within a web app change to work for your windows app
}
}

I'm not sure what your truly inquiring but I believe your attempting is:
public static bool CopyFile(string source, string destination)
{
if(!File.Exist(source))
return false;
if(string.IsNullOrEmpty(destination))
return false;
try
{
using(var reader = File.Open(source))
using(var writer = File.Create(destination))
reader.CopyTo(writer);
return true;
}
catch(IOException ex) { return false; }
}
Bare in mind this will eat your exception, then return false if it fails at any point for any reason.
That would essentially copy the file, I noticed that your trying to read your local application folder. Be careful, as it often requires Administrator Privileges when it resides in several locations within the Operating System.