Telerik Web Forms How to Manipulate the Uploaded Files – RadAsyncUpload – Telerik UI for ASP.NET AJAX

If you need to perform additional actions on uploaded files before saving them (for example, if you are using custom fields), or if you want to manipulate them in memory without saving them, you can use the RadAsyncUpload server-side API. It will allow you to rename uploaded files or save them into a database or other storage media.

In this article, you can find the API that RadAsyncUpload provides for managing files and a few examples that demonstrate common scenarios.

RadAsyncUpload provides the UploadedFiles collection that contains all valid uploaded files.

The UploadedFiles property is of type Telerik.Web.UI.UploadedFileCollection. Each file in the collection is an instance of the UploadedFile class. Table 1 lists the members of the UploadedFile class.

Property or Method
Type (Return Type)
Description

Properties

ContentLength
Int64
The size of the uploaded file, in bytes.

ContentType
string
The MIME type of the uploaded file.

FileName
string
The fully qualified name of the file on the client. (IE6 and some older browsers only). To get a file name that is the same for all browsers, use the GetName() method instead.

InputStream
System.IO.Stream
A stream object that can be used to read the file contents. Note: As of R2 2017 SP2 the temporary files saved to the disk have the .tmp extension. This is due to the security improvement discussed in the Insecure Direct Object Reference article.

Methods

GetName()
string
Returns the name of the uploaded file.

GetNameWithoutExtension()
string
Returns the name of the uploaded file, without the file extension.

GetExtension()
string
Returns the extension of the uploaded file, including the leading dot (“.”)

SaveAs(string, [bool])
none
Save the file to the location specified by the first parameter. The optional second parameter specifies whether to overwrite an existing file if it is found.

GetFieldValue(string)
string
Retrieves a custom field added to the uploaded file.

GetIsFieldChecked(string)
boolean
Retrieves whether a custom check box added to the uploaded file was checked.

Use either the TargetFolder property or the server-side API. If you first set the TargetFolder property and then use the server-side API to manipulate the uploaded files, you may experience the following issues:

• Two copies of the uploaded files are saved. Any valid files will already be saved to the target folder.
• An error appears when attempting a custom .SaveAs() call on an uploaded file. The error points to the temporary folder of the RadAsyncUpload, for example, Could not find file '<physical path to your app>\App_Data\RadUploadTemp\some-uploaded-file.png.tmp'. This is caused by the fact that that the control moved the file to the target folder. The solution is to remove the TargetFolder property and save the files only with your own code.
  • A similar error can appear if antivirus software or other code deletes the temporary file(s) before the FileUploaded event is fired. Thus, you may want to have a try-catch block around the .SaveAs call. RadAsyncUpload handles this internally only when saving to the TargetFolder.

The following example illustrates how to save uploaded files to a location of your choice, in the postback event of another control like a button:

<telerik:RadAsyncUpload RenderMode="Lightweight" id="RadAsyncUpload1" runat="server" />
<asp:Button runat="server" ID="Button1" Text="Submit" OnClick="Button1_Click" />

protected void Button1_Click(object sender, System.EventArgs e)
{
  foreach (UploadedFile f in RadAsyncUpload1.UploadedFiles)
  {
      f.SaveAs( "c:\\uploaded files\\" + f.GetName(), true);
  }
}

Imports Telerik.Web.UI...
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) _
  Handles Button1.Click
    For Each f As UploadedFile In RadAsyncUpload1.UploadedFiles
        f.SaveAs("c:\my files\" & f.GetName, True)
    Next
End Sub 

The following example illustrates how to save uploaded files to a location of your choice in OnFileUpload event:

The OnFileUpload event will be fired for every file in the UploadedFiles collection after postback.

<telerik:RadAsyncUpload RenderMode="Lightweight" id="RadAsyncUpload1" runat="server" OnFileUploaded="RadAsyncUpload1_FileUploaded1"/>
<asp:Button runat="server" ID="Button2" Text="Submit" />

protected void RadAsyncUpload1_FileUploaded1(object sender, FileUploadedEventArgs e)
{
    string path = Server.MapPath("~/Uploads/");
    e.File.SaveAs(path + e.File.GetName());
}

Imports Telerik.Web.UI...
Protected Sub RadAsyncUpload1_FileUploaded(sender As Object, e As FileUploadedEventArgs)
    Dim Path As String
    Path = Server.MapPath("~/Uploads/")
    e.File.SaveAs(Path + e.File.GetName())
End Sub

You can use the InputStream property to access the content of the uploaded files without saving them to a temporary location. This property is useful when you want to insert the file into a database, or process its contents without saving.

The following example demonstrates how to insert the uploaded files into a database using OleDb:

using System.Data.OleDb;
using Telerik.Web.UI;
...
protected void Button1_Click(object sender, System.EventArgs e)
{
  foreach (UploadedFile file in RadAsyncUpload1.UploadedFiles)
  {
      byte[] bytes = new byte[file.ContentLength];
      file.InputStream.Read(bytes, 0, bytes.Length);
      OleDbConnection connection = CreateConnection();
      try
{
           OleDbCommand command = new OleDbCommand(
               "INSERT INTO Images ([Name], [Size], [Content]) VALUES (?, ?, ?)",
              connection);
          command.Parameters.AddWithValue( "@Name", file.GetName());
          command.Parameters.AddWithValue( "@Size", bytes.Length);
          command.Parameters.AddWithValue( "@Content", bytes);
          connection.Open();
          command.ExecuteNonQuery();
      }
       finally
      {
           if (connection.State == Data.ConnectionState.Open)
          {
              connection.Close();
          }
      }
  }
} 

Imports System.Data.OleDb
Imports Telerik.Web.UI
...
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) _
     Handles Button1.Click
    For Each file As UploadedFile In RadAsyncUpload1.UploadedFiles
        Dim bytes(file.ContentLength - 1) As Byte
        file.InputStream.Read(bytes, 0, bytes.Length)
        Dim connection As OleDbConnection = CreateConnection()
        Try
            Dim command As New OleDbCommand("INSERT INTO Images ([Name], [Size], [Content]) VALUES (?, ?, ?)", connection)
            command.Parameters.AddWithValue("@Name", file.GetName())
            command.Parameters.AddWithValue("@Size", bytes.Length)
            command.Parameters.AddWithValue("@Content", bytes)
            connection.Open()
            command.ExecuteNonQuery()
        Finally
            If connection.State = Data.ConnectionState.Open Then
                connection.Close()
            End If
        End Try
    Next
End Sub

The InputStream property is also showcased in the Access temporary file name and manually delete tempfile from RadAsyncUpload how-to article.