[Solved] GridAttachmentColumn without DataSourceID

[Steele]

Hi All,
I am trying to use the GridAttachmentColumn in the Grid, but don't want to have to use an SQLDataSource control.
I have objects and data-layers for the retrieving and control of my file objects, so I was wondering how I fill out this column with the bound information from my datalayer (it is a DataSet)?
At this point, it seems I need to abandon this new column type and use ItemTemplates instead with a nested RadUpload control.
Anyone had any experience with binding this column programmatically?
Thanks,
Steele.

[Veli]

Hello Steele,

You can bind the column to an ObjectDataSource control through the DataSourceID. Thus, you can interface your business data layer with the column.

I am not sure I understand what do you mean by that your data layer is a DataSet? Do you mean that all your attachments that you can download through the GridAttachmentColumn are loaded in a DataSet and reside in server memory? Isn't that a huge overhead if this is the case? The idea behind the GridAttachmentColumn is to bind to a data source control that will fetch a single item from your data source containing your binary attachment data and send it over through the response. Thus, large attachment files are not stored in server memory. If this is not the case, can you, please, clarify?

Regards,
Veli
the Telerik team

[Steele]

It seems that my description of my requirements were lacking.
I am trying to avoid using SQLDataSource controls or the like as the inclusion of them within the interface level goes against the design principles laid down in our framework.
My data layer is not a DataSet but rather the information drawn from it is.  The methodology in fact causes no file data to be stored in memory, as I am replicating (or rather, trying to replicate) the DataSource control that is provided in the examples.  But I need some way of assigning the file data from my DataSet column to the GridAttachmentColumn.
So my object enables me to get the file details (name, date uploaded, etc) and also has fetch/save routines for the file data itself.  I can bind the details just fine (straight out binding to a grid) but cannot find a way to hook up a binding to my fetch/save routines for the file data.
Does that explain better where I am coming from?
Steele.

[Veli]

Yes, better understood. I believe the GridAttachmentColumn would not come in very handy in your scenario, then. Not that it cannot be configured to work in this case, but would not be less of hassle than using a GridTemplateColumn. With the latter you can have a button in the ItemTemplate to download attachments and a RadUpload in the EditItemTemplate to upload them to your database:

<telerik:RadGrid ID="RadGrid1" runat="server">
    <MasterTableView>
        <Columns>
            <telerik:GridTemplateColumn>
                <ItemTemplate>
                    <asp:LinkButton ID="DownloadButton" runat="server"
                        CommandName="DownloadAttachment" Text="Download">
                    </asp:LinkButton>
                </ItemTemplate>
                <EditItemTemplate>
                    <telerik:RadUpload ID="AttachmentUpload" runat="server">
                    </telerik:RadUpload>
                </EditItemTemplate>
            </telerik:GridTemplateColumn>
        </Columns>
    </MasterTableView>
</telerik:RadGrid>

Using RadGrid's ItemCommand event you can both stream download the attachment, as well as upload one on update:

protected void RadGrid1_ItemCommand(object source, GridCommandEventArgs e)
{
    if (e.CommandName == RadGrid.DownloadAttachmentCommandName)
    {
        GridDataItem dataItem = (GridDataItem)e.Item;
        string fileName;
        //use dataItem.GetDataKeyValue() to get data keys incl. filename

        byte[] binaryData;
        //populate binaryData with attachment data

        Response.Clear();
        Response.ContentType = "application/octet-stream";
        Response.AddHeader("content-disposition", "attachment; filename=" + fileName);
        Response.BinaryWrite(binaryData);
        Response.End();
    }

    if (e.CommandName == RadGrid.UpdateCommandName ||
        e.CommandName == RadGrid.PerformInsertCommandName)
    {
        RadUpload attachmentUpload = (RadUpload)e.Item.FindControl("AttachmentUpload");
        if (attachmentUpload.UploadedFiles.Count > 0)
        {
            UploadedFile file = attachmentUpload.UploadedFiles[0];
            System.IO.Stream stream = file.InputStream;
            byte[] binaryData = new byte[stream.Length];
            stream.Read(binaryData, 0, (int)stream.Length);
            stream.Seek(0, System.IO.SeekOrigin.Begin);

            //binaryData contains your uploaded content
            //you can save to your database
        }
    }
}

Veli
the Telerik team

[Jonathan]

How exactly do you place that Binary data into the InsertParameter?

I'm using an ObjectDataSource control to do this and I want to place that binary data into the InsertParameter of the ObjectDataSource control. However, the only available property to which a value can be assigned is DefaultValue, which is a string. The BinaryData is a 1-dimensional byte array. How do you get that to work?

[Veli]

Hi Jonathan,

You can use an event handler for the Inserting event of the ObjectDataSource control. The insert operation is performed by calling the Insert method of the data source control inside RadGrid's PerformInsert command:

protected void RadGrid1_ItemCommand(object source, GridCommandEventArgs e)
{
    if (e.CommandName == RadGrid.PerformInsertCommandName)
    {
        AttachmentDataSource.Insert(); //the data source control
    }
}

Veli
the Telerik team

[Jonathan]

Hey Veli,

You gave me a brilliant idea that worked.

Here's my implementation for reference of anyone else who may have the same problem:

Because the ObjectDataSource.InserParameters.Value uses a String, I can't pass a 1-Dimensional array to it directly. So in the RadGrid.InsertCommand, I grab the file stream and store it into a Session variable which automatically assumes the DataType of whatever is being assigned to it:

If e.Item.OwnerTableView.DataSourceID = "ObjectDataSource4" Then
    'Stream the file data into the object.
    Dim ru As RadUpload = DirectCast(item("Document_Store").Controls(0), RadUpload)
    If ru.UploadedFiles.Count > 0 Then
        Dim file As UploadedFile = ru.UploadedFiles(0)
        Dim stream As System.IO.Stream = file.InputStream
        Dim BinaryData(stream.Length - 1) As Byte
        stream.Read(BinaryData, 0, CInt(stream.Length))
        Session("File") = BinaryData
    End If
End If

Then in the ObjectDataSource.Inserting event, I pass the contents of the session variable (which now assumes the datatype of a 1-dimensional array of Bytes) directly to the insert parameter which would already be of the correct data type:

Dim pars As IDictionary = e.InputParameters
pars("Document_Store") = Session("File")

This way, I don't have to call the Insert command of the ObjectDataSource directly. I simply ride the sequence of events as they bubble up through the object hierarchy from the instant the InsertCommand is triggered from the RadGrid by the user.

This method seems more elegant to me.

Thanks for your suggestions, Veli.

Regards,
John 

[SKande]

How do we delete the file attachment using the Link button template because it does not have a unique name to get the file name