I need to store some data to use for a windows8 based mobile application. Data needed to be reuse. For an example need to store 4 phone numbers to send messages and another one to send calls. How can I store data in here. I have heard about isolated storage. Is it the way or can I connect it to a database. Will it application be too heavy if it is connected to a database?
Not sure what you mean by connect to a database.
In Windows Phone 8, Isolated Storage refers to storage each app has on the phone, and I don't think (I am not sure actually) other apps can access it. Basically if you need to save something it would look like that.
The following code is to save something:
IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication();
//create new file
using (StreamWriter writeFile = new StreamWriter(new IsolatedStorageFileStream("myFile.txt", FileMode.Create, FileAccess.Write, myIsolatedStorage)))
{
string someTextData = "This is some text data to be saved in a new text file in the IsolatedStorage!";
writeFile.WriteLine(someTextData);
writeFile.Close();
}
To access that file at anytime you would just do this:
IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication();
IsolatedStorageFileStream fileStream = myIsolatedStorage.OpenFile("myFile.txt", FileMode.Open, FileAccess.Read);
using (StreamReader reader = new StreamReader(fileStream))
{ //Visualize the text data in a TextBlock text
this.text.Text = reader.ReadLine();
}
Here is the link. http://www.geekchamp.com/tips/all-about-wp7-isolated-storage-read-and-save-text-files
Isolated Storage would allow you to permenately store files there and retrieve it even when the user quits their application.
Related
I want to write entries to a log file stored in Azure file storage. I currently have this:
var log = "My log entry";
var client = _storageAccount.CreateCloudFileClient();
var share = client.GetShareReference(Config.LogShare);
share.CreateIfNotExists();
var root = share.GetRootDirectoryReference();
var logfile = root.GetFileReference("log.txt");
if (!logfile.Exists()) logfile.Create(0);
// What goes here to append to the file...?
I can see plenty of examples of how to do this with Blobs, or how to upload an entire file, but how do I just append to an existing file?
I have tried this:
var buffer = Encoding.GetEncoding("UTF-8").GetBytes(log.ToCharArray());
using (var fileStream = logfile.OpenWrite(0)) {
fileStream.Write(buffer, (int)logfile.Properties.Length, buffer.Length);
}
But then I get this error:
The remote server returned an error: (416) The range specified is invalid for the current size of the resource..
I managed to work this out myself. You just need to increase the size of the file by the number of new bytes you want to write to it, and then write the new data to that new empty space at the end of the file, like this:
var client = _storageAccount.CreateCloudFileClient();
var share = client.GetShareReference(Config.LogShare);
share.CreateIfNotExists();
var root = share.GetRootDirectoryReference();
var logfile = root.GetFileReference("log.txt");
if (!logfile.Exists()) logfile.Create(0);
var buffer = Encoding.UTF8.GetBytes($"{log}\r\n");
logfile.Resize(logfile.Properties.Length + buffer.Length);
using (var fileStream = logfile.OpenWrite(null)) {
fileStream.Seek(buffer.Length * -1, SeekOrigin.End);
fileStream.Write(buffer, 0, buffer.Length);
}
You can do this with blobs https://blogs.msdn.microsoft.com/windowsazurestorage/2015/04/13/introducing-azure-storage-append-blob/
Shame it doesn't work with files too
Azure file storage REST API doesn't support appending to an existing file. To achieve this, please mount the file share to your machine as a drive, and append to the file just like simple local files.
Actually, I don't think you really need appending functionality per your code above. You can specify the file size in CloudFile.OpenWrite() / CloudFile.Create(), or try CloudFile.UploadFromStream() instead of CloudFile.OpenWrite().
This error could also be due to multi-threaded access.
I bet if you tried to lock the file before you access it, you will not face this problem.
There are many ways to update the file.
Since you already managed to get the share, the root, the folder and the file.. Here is a portion of my code that worked for me.
if (!fileLock.IsWriteLockHeld) fileLock.EnterWriteLock();
try
{
using (var stream = new MemoryStream(content, false))
{
file.UploadFromStream(stream, null, options);
}
}
catch (Exception ex)
{
File.AppendAllText(FileName, ex.ToString());
}
finally
{
if (fileLock.IsWriteLockHeld)
fileLock.ExitWriteLock();
}
Where fileLock is declared as:
protected ReaderWriterLockSlim fileLock = new ReaderWriterLockSlim();
Having said that, I am not saying that this is the best way ever to do it.
The two things I would like you to keep in mind :
1-Lock the resource that is likely to be accessed by more than one thread (That is so common in AZURE)
2- Get familiar with asynchronous methods that Azure provides.. use them when they suit well.
Coming back to your original problem about appending to the existing file..
All the methods of the CloudFile will overwrite the existing file. Cloud Files are not for frequent writing, and they indeed impact performance if you keep writing on them frequently, add the lock impact on performance, they will be horrible.
Cloud files are meant to store big bulk of data once and for all, if you want to add another bulk you have the choice of creating another file.
Have all your data with the client till they reach some size and create an algorith to select the file name and upload them all at once.
I try to develop several WP8 apps using the same credentials for all(same user and password).So if the user choose to change his credentials he does only once in one app and it will change for all.
Until now i used Isolatedstorage to save the credentials(as shown below) but im wondering if the files would be accessible by all the apps...i guess they would not.
So what solution do you have ?
thanks for your help
public static void SaveToFile(byte[] Encryptedfile, string FileName)
{
using (var SaveApplicationFile = IsolatedStorageFile.GetUserStoreForApplication())
{
SaveApplicationFile.DeleteFile(FileName);
using (IsolatedStorageFileStream fileAsStream = new IsolatedStorageFileStream(FileName, System.IO.FileMode.Create, FileAccess.Write, SaveApplicationFile))
{
using (Stream writer = new StreamWriter(fileAsStream).BaseStream)
{
writer.Write(Encryptedfile, 0, Encryptedfile.Length);
}
}
}
}
You can't access IsolatedStorage of other App.
Nor you can't save on SD card.
Maybe consider using Skydrive or other exteral storage.
Another idea, I'm thinking about - maybe you can use MediaLibrary and Save Picture there. And use this picture as a container for some data - maybe using Steganography ;)
I have created a silverlight project that captures the image through the webcam and stores it in my local hard, but I don't want to save it on the local hard I want to store it in my project folder then store the path in SQL database.
Please Help!
You could try and save the image directly as a bitstream to the DB maybe?
private static ImageElementContract ImageToImageElementContract(Image image)
{
WriteableBitmap bmp = new WriteableBitmap(image, null);
ImageTools.ExtendedImage myImage = new ImageTools.ExtendedImage();
myImage = ImageExtensions.ToImage(bmp);
MemoryStream mStream = new MemoryStream();
JpegEncoder encoder = new JpegEncoder();
encoder.Quality = 100;
encoder.Encode(myImage, mStream);
imageContract.ImageStream = mStream.ToArray();
return imageContract;
}
Should give you a stream, which you can pass to the DB and put back together if you need it again. It's hard to tell what your using it for. There's not much detail in your question
I want to tombstone the last page that the user was on and to retrieve it when the user comes back to the app. All of the tombstoning examples on the Internet deal with saving some data or the state of the page that the user has edited somehow (i.e inputed text in the textbox). In my app I don't have anything for the user to modify/edit so I just want to save the last visited page that the user was on. I tried to use some online examples that used PhoneApplicationService.Current.State but with no success.
Thank you to anyone who would like to help me out resolving this issue!
To locally store persistent data (data that should remain even when the user closes the app), you can use Isolated Storage.
So, in your app's Deactivated event, you can write the page's name to Isolated Storage like this:
//You get the Isolated Storage for your app (other apps can't access it)
IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication();
//if the file already exists, delete it (since we're going to write a new one)
if (isf.FileExists("lastpage.txt")) isf.DeleteFile("lastpage.txt");
using (var isoFileStream = new IsolatedStorageFileStream("lastpage.txt", FileMode.OpenOrCreate, isf))
{
//open a StreamWriter to write the file
using (var sw = new StreamWriter(isoFileStream))
{
//NavigationService.CurrentSource returns the current page
//we can write this to the file
sw.WriteLine((Application.Current.RootVisual as PhoneApplicationFrame).CurrentSource.ToString());
}
}
This will write the current page's name to the Isolated Storage. Then, in your OnNavigatedto method of your main page (the page that first opens normally) you can read the file name and navigate to it:
protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
{
IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication();
string lastpage = string.Empty;
if (isf.FileExists("lastpage.txt"))
{
using (var isoFileStream = new IsolatedStorageFileStream("lastpage.txt", FileMode.Open, isf))
{
//read the file using a StreamReader
using (var sr = new StreamReader(isoFileStream))
{
//get the uri we wrote and then convert it from a String to a Uri
lastpage = sr.ReadLine().Replace("file:///", "");
}
}
(Application.Current.RootVisual as PhoneApplicationFrame).Navigate(new Uri(lastpage, UriKind.Relative));
}
base.OnNavigatedTo(e);
}
This should read in the file you saved and then convert the string into an actual URI that you can pass to the NavigationService.
You can then delete the text file after it's been read so that it doesn't always keep jumping to that page.
In addition you can use this for getting the page name ,string PageName = (Application.Current.RootVisual as PhoneApplicationPage).Name; for getting the current page name
While I agree all the above options are possible, they are not really the correct way of doing something within a WP7.
It's better to construct a navigation page at the start of your app for properly controlling navigation, it also helps with managing back key events while using the app and prevents hiccups.
See Here for one example of implementing this:
Properly Exiting Silverlight-based WP7
With this done use the advice on storing values in isolated storage / application settings to then just store the "Current Page" state value (e.g. value of Page.GamePage) then the app navigation will direct you accordingly.
BUT beware when just storing the current page itself as you also need to save the correct state of any values or User entered data on that page when it tombstones as well, this the above advice should lead you in the right direction.
Hope this helps
I've parsed these files in regular C# applications, but the IO methods for the files are different in Silverlight, and I can't seem to find the right methods. Searches haven't turned up any information I can use. For the real application I'll be receiving XML from the server, but for the prototype I just need to parse a file with some sample data in it.
You can save the Excel file as XML. An example can be found in this link
This way you can keep your import procedure the same and process the data as when you go live.
To access files from the user's machine you are required to use the OpenFileDialog and SaveFileDialog. Without elevated trust (requires out of browser apps) you will not be able to know anything more than the filename the user selected for input/saving; you will have no idea what the path is to this file. This function can only be called as the result of a user taking an action such as clicking a button; otherwise it will fail because Silverlight does not want malicious code prompting a user with annoying dialogs automatically.
To do this you would do something as follows:
var openFile = new OpenFileDialog();
if ( open.ShowDialog() == true ) // Sadly this is a nullable bool so this is necessary
{
using( Stream myStream = openFile.File.OpenRead() )
using ( var reader = new StreamReader( myStream ))
{
...
}
}