DataGrid and MultiBind - asp.net

Question

I'm new to ASP.NET and are struggling with displaying data in a GridView. I got most of it working with help from this forum. Currently I'm trying to build a file name from an ID and a "file extension" from a database, but got stuck. I guess I need to use MultiBind to get this working? My file name is ID + "_tn" + file extension, and this is my code.
<asp:GridView ID="HitGridView" runat="server" onrowdatabound="HitsRowBid">
<Columns>
<asp:TemplateField HeaderText="Street">
<ItemTemplate>
<asp:TextBox ID="Adress" runat="server" width="200" Text='<%# Bind("StreetName") %>'></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Image">
<ItemTemplate>
<asp:ImageButton ID="defaultImg" runat="server" ImageUrl='<%# Bind("ImgId") %>'/>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
and in code behind
protected void HitsRowBid(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
ImageButton imgBtn = (ImageButton)e.Row.FindControl("defaultImg");
imgBtn.ImageUrl = "Content/FileUpload/" + imgBtn.ImageUrl + "_tn" + ".jpg";
}
}
But how do I get the file extension that is stored in the database?

Answer 1

I mainly use ListViews, but there are a couple of ways to accomplish this. One way would be to use DataKeys when databinding and retrieve the value by using the row index in the onrowdatabound event. Another option would be to write a helper method in codebehind and call it during databinding, something like:
protected string FormatImagePath(string fileName)
{
string imagePath = Request.ApplicationPath.TrimEnd('/') + "/previews/" + fileName;
FileInfo testFile = new FileInfo(Helpers.BaseSiteFilePath + #"previews\\" + fileName);
if (!testFile.Exists)
{
imagePath = Request.ApplicationPath.TrimEnd('/') + "/images/no_preview.png";
}
return imagePath;
}
Calling it like such:
ImageUrl='<%# FormatImagePath(Eval("PreviewURL").ToString()) %>'