how to check the duplicate filename in asp:fileupload? - asp.net

Question

i have an updatepanel and inside of it the contenttemplate is an asp:FileUpload..now when i will try to choose the file i want to check the filename in the database..i know my database part but how will i call the function in the server like for asp:TextBox i can use OnTextChanged something like that..but for asp:FileUpload is there anything by which i can check the filename and without clicking the button add?? my code
<asp:UpdatePanel runat="server" ID="fileupdatepanel">
<ContentTemplate>
<asp:FileUpload ID="tutorialupload" runat="server" AutoPostBack="true" OnLoad="filename_Changed" />
<asp:Label runat="server" ID="f1"></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
<asp:Button ID="addbttu" runat="server" Text="Add" OnClick="addtutorial_Click" />
my aspx.cs code
protected void filename_Changed(object sender, EventArgs e)
{
string con = " ";
con = ConfigurationManager.ConnectionStrings["ConnectionString"].ToString();
SqlConnection objsqlconn = new SqlConnection(con);
objsqlconn.Open();
string tuname = tutorialupload.PostedFile.FileName;
tuname = tuname.Substring(0, tuname.LastIndexOf("."));
SqlCommand objcmd = new SqlCommand("Select tutorialid from tutorialtable where tutorialname='" + tuname + "'", objsqlconn);
SqlDataReader grpIDreader = objcmd.ExecuteReader();
grpIDreader.Read();
if (grpIDreader.HasRows)
{
f1.Text = "Duplicate filename.Sorry.";
}
else
{
f1.Text = "";
}
objsqlconn.Close();
}
now when i will choose the file..i want to call this function filename_Changed() and it will give me the result whether the filename is present or not..so i want to do it without clicking my the add button??

Answer 1

You should use the has file property, when true do you DB check, something like this
protected void UploadButton_Click(object sender, EventArgs e)
{
if (FileUpload1.HasFile)
// Before attempting to save the file, do something
else
// Notify the user that a file was not uploaded.
UploadStatusLabel.Text = "You did not specify a file to upload.";
}

Answer 2

Here is how you can detect the change in the selected file name using JavaScript through the FileUpload onChange event.
ASPX Page: Make sure to set EnablePageMethods = true in the ScriptManager object.
<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true"></asp:ScriptManager>
<asp:UpdatePanel runat="server" ID="fileupdatepanel">
<ContentTemplate>
<asp:FileUpload ID="tutorialupload" runat="server" OnChange="CheckFileName(this)" />
<asp:Label runat="server" ID="f1"></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
<asp:Button ID="addbttu" runat="server" Text="Add" OnClick="addtutorial_Click" />
JavaScript:
function CheckFileName(oFile)
{
PageMethods.FileNameChecker(oFile.value, OnSucceeded);
}
function OnSucceeded(result, userContext, methodName)
{
lbl = document.getElementById('<%=f1.ClientID %>');
if (methodName == "FileNameChecker")
{
if (result == true)
{
lbl.innerHTML = 'Duplicate filename.Sorry.';
lbl.style.color = "red";
}
else
{
lbl.innerHTML = '';
}
}
}
C# Code-Behind: You can call a WebMethod to check if the new selected filename exists in the DB:
You need to reference the following:
using System.Web.Services;
Then add the following method and make sure you put [WebMethod] before method declaration:
[WebMethod]
public static bool FileNameChecker(string newFileName)
{
string con = " ";
con = ConfigurationManager.ConnectionStrings["ConnectionString"].ToString();
SqlConnection objsqlconn = new SqlConnection(con);
objsqlconn.Open();
string x = newFileName.Substring(0,newFileName.LastIndexOf("\\"));
string tuname = newFileName.Substring(newFileName.LastIndexOf("\\") + 1, newFileName.Length - x.Length - 1);
tuname = tuname.Substring(0, tuname.LastIndexOf("."));
SqlCommand objcmd = new SqlCommand("Select tutorialid from tutorialtable where tutorialname='" + tuname + "'", objsqlconn);
SqlDataReader grpIDreader = objcmd.ExecuteReader();
grpIDreader.Read();
bool found = false;
if (grpIDreader.HasRows)
found = true;
objsqlconn.Close();
return found;
}