Hi,

I have a gridview (GridView1) which has several bound fields.  One of the
fields (DirectoryListing) is a template field.  In the Edit template field, I
have a textbox (TextBox1), a fileupload control (FileBrowse1) and a button
control (SelectButton). 

Definition of GridView1 Template Field
            <asp:TemplateField HeaderText="DirectoryListing"
                SortExpression="DirectoryListing">
                <EditItemTemplate>
                    <asp:TextBox ID="TextBox1" runat="server"
                        Text='<%# Bind("DirectoryListing") %>'
Width="128px"></asp:TextBox>
                    <br />
                    <asp:FileUpload ID="FileSelect" runat="server" />

                    <asp:Button ID="SelectButton" runat="server"
onclick="SelectButton_Click"
                        Text="Select File" />
                </EditItemTemplate>
                <ItemTemplate>
                    <asp:Label ID="Label1" runat="server" Text='<%#
Eval("DirectoryListing") %>'></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>


In edit mode, the user can click on FileBrowse1 and select a file, then they
can click on the SelectButton to move FileBrowse1.PostedFile.FileName to the
TextBox1.

I created a SelectButten_Click event as follows:

    protected void SelectButton_Click(object sender, EventArgs e)
    {
        TextBox1.Text = FileBrowse1.PostedFile.FileName.ToString();
    }

I get error:
Compilation Error
Description: An error occurred during the compilation of a resource required
to service this request. Please review the following specific error details
and modify your source code appropriately.

Compiler Error Message: CS0103: The name 'TextBox1' does not exist in the
current context

Source Error:



Line 89:     protected void SelectButton_Click(object sender, EventArgs e)
Line 90:     {
Line 91:         TextBox1.Text = FileBrowse1.PostedFile.FileName.ToString();
Line 92:     }
Line 93:
Source File:
c:\Inetpub\wwwroot\CMWebManager\SystemAdminOnly\Copies\Test-with Butto_Click
Examples.aspx    Line: 91


If I have a TextBox, FileUpload and Butten controls outside of a template
control, the above works.  I just don't know how to reference the controls
triggered by a click event from inside a template control.

Any help would be appreciated.

Hi Morris,

Since the TextBox and the FileUpload controls are put in the EditTemplate
we cannot use their ID directly to get the reference of them.

To achieve the requirement we can try following code:

protected void SelectButton_Click(object sender, EventArgs e)
        {

          Button b = (Button)sender;
          TextBox tb=  b.FindControl("TextBox1") as TextBox;
          FileUpload fu = b.FindControl("FileSelect") as FileUpload;
          if (tb != null&&fu!=null)
          {
              tb.Text = fu.PostedFile.FileName;
          }
        }

In the above code, we get the sender first. Since it's triggered by the
SelectButton the sender is the SelectButton. Now we've got the reference of
this button and can use the Control.FindControl method to get the reference
of the TextBox and the FileUpload controls. The FindControl method will
search through the naming container of the caller control to find the
control we need.

Here's the documentation about FindControl method:
http://msdn.microsoft.com/en-us/library/486wc64h.aspx

Please let me know if it works and feel free to ask if you need further
assistance.

Regards,
Allen Chen
Microsoft Online Community Support

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Thanks much.  Worked perfectly.

I question.  Instead of using Browse to get the file name, then clicking
Select to set TextBox1 to the name of the file selected, is there an event
that can be trigerred when the file name field of the FileUpload control
changes?  I want to see if I can eliminate the user hving to click the Select
button to set the value for the TextBox1.

Once again, I appreciate the help.  I am learning by your examples and
moving well on my project.
Show quoteHide quote

Hi Morris,

To do this we need to call JavaScript. The key point is to find the
ClientID of the TextBox on the current row. The code is as below:

Aspx:
<head runat="server">
    <title>Untitled Page</title>
<script type="text/javascript">

function ChangeValue(sender, i)
    {
    var t=i.id
    document.getElementById(t).value=sender.value;
    }
</script>

</head>

...................

<asp:FileUpload ID="FileSelect" runat="server" onchange='<%#
"ChangeValue(this,"
+((GridViewRow)Container).FindControl("TextBox1").ClientID + ")"%>'/>

...................

If you have further questions please feel free to ask.

Regards,
Allen Chen
Microsoft Online Community Support

Thanks, worked perfectly.  Where would I find documentation that onchange is
a valid property for the FileUpload control?  I tried to search but could not
find it.

One more question related to this fileupload control, can it be bound to a
field in a table?  So on edit if the bound field has a value then the file
path and name would show in the textbox component of the fileupload.  The
user can then click on browse button to select a new file.  On the gridview
update button the value in the textbox component would be saved to the bound
field.  If this is possible then it would eliminate the need to have a
seperate textbox that is in turn bound to a field.

Once again Allen, you have been most responsive and extremely helpful.
Show quoteHide quote

Hi Morris:

Quote from Morris =================================================

Thanks, worked perfectly.  Where would I find documentation that onchange
is
a valid property for the FileUpload control?  I tried to search but could
not
find it.
=================================================

The asp:FileUpload control will render <input type="file" />. From the
following documentation we can see onchange is supported by fileupload.
http://www.w3schools.com/htmldom/event_onchange.asp

Quote from Morris =================================================
One more question related to this fileupload control, can it be bound to a
field in a table?  So on edit if the bound field has a value then the file
path and name would show in the textbox component of the fileupload.
=================================================

As far as I know, due to security reason, we cannot assign a value to the
fileupload. It can only be assigned by user interaction. If it's allowed a
malicious server can easily steal any file he wants to get from the client.


If you have further questions please feel free to ask.

Regards,
Allen Chen
Microsoft Online Community Support

Thanks for the info.

Is there anyway that I can find detailed properties of the file to be
uploaded?  We may need to upload .wav files but their detailed properties
need ot be 11 KHz 8bit mono.  I use the
System.IO.Path.GetExtension(FileUploadExcel.PostedFile.FileName) to check for
the extension before uploading but I need more specifics.  I did not find
anything when searching for System.IO.Path members.

Show quoteHide quote

Hi Morris,

Thanks for your update.

To do this we can refer to the WAVE format:
http://ccrma.stanford.edu/CCRMA/Courses/422/projects/WaveFormat/

We can get all the bytes of the wav file at server side via
.FileUpload.FileBytes.
Here's a sample that demonstrates how to achieve the requirement:

Aspx:
    <asp:FileUpload ID="FileUpload1" runat="server" />
    <asp:Button ID="Button1" runat="server"
        Text="Upload" onclick="Button1_Click" />

Aspx.cs:
    protected void Button1_Click(object sender, EventArgs e)
        {
            bool _ismono = false;
            int _samplerate = 0;
            int _bitspersample = 0;
           byte[] filebytes= this.FileUpload1.FileBytes;
           if (filebytes.Length >
44&&this.FileUpload1.FileName.ToLower().EndsWith(".wav"))
           {
               _ismono = filebytes[22] == 1 && filebytes[23] == 0;
               byte[] samplerate = new byte[4] { filebytes[24],
filebytes[25], filebytes[26], filebytes[27] };
               _samplerate = BitConverter.ToInt32(samplerate, 0);
               byte[] bitspersample = new byte[2] { filebytes[34],
filebytes[35] };
               _bitspersample = BitConverter.ToInt16(bitspersample, 0);
           }
        }

If you like you can also read other chunks in the above way.

Please have a try and let me know if it works and feel free to ask if you
need further assistance.

Regards,
Allen Chen
Microsoft Online Support

Thanks.  I will try this in the new few days and let you know.

Is there anyway to get this info before uploading file?  I use the following
to check the extension of the file selected for upload, so can I check other
properties before uploading?

                String strFileExt =
System.IO.Path.GetExtension(FileUploadExcel.PostedFile.FileName);
                if (strFileExt == ".xls" || strFileExt == ".wav")


Show quoteHide quote

Hi Morris,

Morris ==================================================
Is there anyway to get this info before uploading file?
==================================================

To achieve this requirement we need to check the file at client side.
ASP.NET is not the proper technique for this task since ASP.NET code runs
at server side. What we need is a RIA(Rich Internet applications) technique
such as Silverlight.

Here's the Silverlight code that can achieve the requirement:

XAML:
  <StackPanel>
            <TextBlock x:Name="TextBlock1"></TextBlock>
            <Button Width="100" Height="50" Click="Button_Click"
Content="Select File"></Button>
        </StackPanel>
XAML.cs:
    private void Button_Click(object sender, RoutedEventArgs e)
        {
            // Create open file dialog box
            OpenFileDialog openFileDialog1 = new OpenFileDialog();
            openFileDialog1.Filter = "Wav File(*.WAV)|*.WAV";
            openFileDialog1.FilterIndex = 1;

            if (openFileDialog1.ShowDialog() == true)
            {
                //Open the selected file to read.
                using (System.IO.Stream fileStream =
openFileDialog1.File.OpenRead())
                {

                    bool _ismono = false;
                    int _samplerate = 0;
                    int _bitspersample = 0;
                    byte[] filebytes = new byte[(int)fileStream.Length];
                    fileStream.Read(filebytes, 0, filebytes.Length);
                    if (filebytes.Length > 44)
                    {
                        _ismono = filebytes[22] == 1 && filebytes[23] == 0;
                        byte[] samplerate = new byte[4] { filebytes[24],
filebytes[25], filebytes[26], filebytes[27] };
                        _samplerate = BitConverter.ToInt32(samplerate, 0);
                        byte[] bitspersample = new byte[2] { filebytes[34],
filebytes[35] };
                        _bitspersample =
BitConverter.ToInt16(bitspersample, 0);

                    }
                    TextBlock1.Text = String.Empty;
                    TextBlock1.Text += _ismono ? "This WAV is Mono" : "This
WAV is not Mono";
                    TextBlock1.Text += "\r\nSample rate is: " + _samplerate;
                    TextBlock1.Text += "\r\nBit sample rate is: " +
_bitspersample;

                    //Decide whether to upload this file here
                    //You can upload the filebytes to server
                }
            }
        }

You can get started to learn Silverlight from here:
http://silverlight.net/

Please feel free to ask if you have further questions.
Regards,
Allen Chen
Microsoft Online Support

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