<

File Handling In SilverLight

Published on
8,520 Points
5,320 Views
2 Endorsements
Last Modified:
In real time programming I have yet to see any application which does not need to work with files in one or the other way. Every programming Language gives a way to handle files, and so does Silverlight. Here we are going to discuss about the techniques, or I should say, the methods we can follow for handling files.

In My Previous Article we saw how we can increase our application's Isolated Area. How can we handle the files in the Isolated storage area. By File Handling I mean The Following :

1.Creating Files
2.Reading Files
3.Getting List of Files
4.Uploading The Existing Files to the Isolated Area.
5.Deleting Files


So let's get started. First we need a Silverlight application, and then we can add the controls and code to take care of the above functions.

 

1. Create FileUploadSLApp


Create a new Silverlight Application I am naming it as "FileUploadSLApp". And leave the other settings as it is.

 

2. Create Usercontrol


We can use MainPage.xaml or can create our own silverlight user control (.xaml). For this example I am going with the MainPage.xaml. The Usercontrol of the Mainpage.xaml will look like:
 
<UserControl x:Class="FileUploadSLApp.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480"
Width="400" Height="300">
<Grid x:Name="LayoutRoot" Background="White">
<Canvas Canvas.Left="10" Canvas.Top="10"> 
<Button Content="Upload" Height="20" Click="Button_Click_1" Margin="10,60,162,54" VerticalAlignment="Bottom" d:LayoutOverrides="Width, Height" HorizontalAlignment="Right" Background="#FF2770AF"></Button>
<TextBox Text="Write File Name with Extention" Margin="10,10,0,0" x:Name="txtFileName"></TextBox>
<Button Content="Read Eile" Height="20" Click="Button_Click" Margin="65,60,162,54" VerticalAlignment="Bottom" d:LayoutOverrides="Width, Height" HorizontalAlignment="Right" Background="#FF2770AF"></Button>
<Button Content="Get List" Height="20" Click="Button_Click_2" Margin="130,60,162,54" VerticalAlignment="Bottom" d:LayoutOverrides="Width, Height" HorizontalAlignment="Right" Background="#FF2770AF"></Button>
<Button x:Name="btnDelete" Height="20" Margin="190,60,251,8" Content="Delete File" Click="btnDelete_Click"/>
<Button x:Name="btnWrite" Height="20" Margin="270,60,36,8" Content="Write" Click="btnWrite_Click" />
<TextBlock Height="20" Margin="10,100,126,79" VerticalAlignment="Bottom" Text="Select File to uload" TextWrapping="Wrap" FontSize="16" x:Name="txtStatus"/>
<TextBox Text="Enter The File Contents here......" Margin="10,140,0,0" x:Name="txtContent"></TextBox>
</Canvas>
</Grid>
</UserControl>

Open in new window



The Page will Look like
 Image FIle
 

3. Create File


In this section we will create a text file in the isolated storage area with the name as given by the user in te textbox. First we will check whether the file exist in the isolated storage area or not. If it does exist then we will create a new file with the name and if it exists then we will append the contents at the start of the file which user inputs in the textbox.

Now let us create the event handler for the button and navigate to the event.

 
private void btnWrite_Click(object sender, RoutedEventArgs e)
{
    using (var MyAppStore = IsolatedStorageFile.GetUserStoreForApplication())
    {
        if (!(MyAppStore.FileExists(txtFileName.Text)))
        {
            MessageBox.Show("File does not exist , we are creating one for you ");
            IsolatedStorageFileStream file = MyAppStore.CreateFile(txtFileName.Text);
            file.Close();
        }
        using (StreamWriter sw = new StreamWriter(MyAppStore.OpenFile(txtFileName.Text, FileMode.Open, FileAccess.Write)))
        {
            sw.WriteLine(txtContent.Text);
        }
        txtContent.Text = "";
        txtFileName.Text = "";
        MessageBox.Show("File Writen");
    }
} 

Open in new window


4. Reading Files


This section of the article shows that how can we read a text file from the Isolated storage area of the application. We have Already created a button and the event handler for this in the .xaml file so let us navigate to the event and code there

 
private void Button_Click(object sender, RoutedEventArgs e)
{
    //craeing a new link to the Application store for reading file in IsolatedStorage
    using (var MyAppStore = IsolatedStorageFile.GetUserStoreForApplication())
    {
        //checking the existance of the file
        if (!(MyAppStore.FileExists(txtFileName.Text)))
        {
            //if doesnot exist prompt the user 
            MessageBox.Show("File does not exist ");
            //Clear the text from the textbox
            txtFileName.Text = string.Empty;
        }
        //if file does exist
        else
        {
            //create a stream reader to read the file
            using (StreamReader sr = new StreamReader(MyAppStore.OpenFile(txtFileName.Text, FileMode.Open, FileAccess.ReadWrite)))
            {
                //read file till end and post the contenst in hte textblock
                txtStatus.Text = sr.ReadToEnd();
            }
        }
    }
} 

Open in new window


5. Getting List of Files from the Isolated Storage


In this section we will get the list file in the isolated storage area and Display it in the TextBlock. for Directory Handling please read next article Now navigating to the event handler

 
private void Button_Click_2(object sender, RoutedEventArgs e)
{
    //clearing the textblockstatus to ensure that it is not having any text
    txtStatus.Text = string.Empty;
    //getting the handler for the isolated store
    using (var MyAppStore = IsolatedStorageFile.GetUserStoreForApplication())
    {
        //holding the array (list) of file names into a string array
        string[] str = MyAppStore.GetFileNames();
        //creating a foreach loop to go through each elemen of the array
        foreach (string s in str)
        {
            //printing the filename in the textblock with a new line.
            txtStatus.Text = txtStatus.Text + Environment.NewLine + s;
        }
    }
} 

Open in new window


6. Uploading File


In this section we will upload any file in the isolated storage area. and then access it from there for future use.

 
private void Button_Click_1(object sender, RoutedEventArgs e)
{
    //creating the refrence for the dialog
    OpenFileDialog dlg = new OpenFileDialog();
    //creating the filter for the dialog
    dlg.Filter = "All files (*.*)|*.*";
    //Displaying the Dialog box remeber this should be user itnitated.
    if (dlg.ShowDialog() == true)
    {
        txtStatus.Text = "Uploading Files ";
        // Save all selected files into application's isolated storage 
        IsolatedStorageFile iso = IsolatedStorageFile.GetUserStoreForApplication();
        //holding the file name into a string variable for later use
        string strname = dlg.File.Name;
        //creating a filestream and reading the contents of the selected file
        using (Stream fileStream = dlg.File.OpenRead())
        {
            //craeing a new IsolatedStorageFileStream for certaing new file in IsolatedStorage
            using (IsolatedStorageFileStream isoStream =
                    new IsolatedStorageFileStream(strname, FileMode.Create, iso))
            {
                // Read and write the data block by block until finish 
                while (true)
                {
                    //get the bytes to write in the file.
                    byte[] buffer = new byte[fileStream.Length];
                    // byte[] buffer = new byte[100001];
                    int count = fileStream.Read(buffer, 0, buffer.Length);
                    if (count > 0)
                    {
                        isoStream.Write(buffer, 0, count);
                    }
                    else
                    {
                        break;
                    }
                }
            }
            txtStatus.Text = "Files Uploaded";
        }
    }
} 

Open in new window


7. Delete File


In this section we will delete any file from the isolated storage area with the name as given by the user in te textbox. Moving towards the event Handler

 
private void btnDelete_Click(object sender, RoutedEventArgs e)
{
    //getting the handler for the store
    using (var MyAppStore = IsolatedStorageFile.GetUserStoreForApplication())
    {
        //Checking if file doesnot exist
        if (!(MyAppStore.FileExists(txtFileName.Text)))
        {
            //prompt the user that file does not exist
            MessageBox.Show("File does not exist ");
        }
        //if file does exist
        else
        {
            //delete it from the store
            MyAppStore.DeleteFile(txtFileName.Text);
            //prompt the user that the file is deleted
            MessageBox.Show("Deleted");
        }
        //clear the textbox containg the file name
        txtFileName.Text = string.Empty;
    }
} 

Open in new window


The Code Is Attached you can Download the files and enjoy file handling


--------------------------------------------------------------------------------
Thanks and Regards
Meetu Choudhary
MVP.
My Blog || My Web || My Forums
2
Comment
0 Comments

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Join & Write a Comment

This is Part 3 in a 3-part series on Experts Exchange to discuss error handling in VBA code written for Excel. Part 1 of this series discussed basic error handling code using VBA. http://www.experts-exchange.com/videos/1478/Excel-Error-Handlin…
Basic Overview of office 365 user portal

Keep in touch with Experts Exchange

Tech news and trends delivered to your inbox every month