Downloading a file from SQL Server - ArgumentOutOfRangeException - asp.net

Question

I'm trying to download files from an SQL Server 2012 database using GridView. I am getting an ArgumentOutOfRangeException giving me this error:
Index was out of range. Must be non-negative and less than the size of the collection.
on:
Dim fileid As Integer = Convert.ToInt32(GridView1.DataKeys(gvrow.RowIndex).Value.ToString())
Code concerned:
Protected Sub lnkDownload_Click(ByVal sender As Object, ByVal e As EventArgs)
Dim lnkbtn As LinkButton = TryCast(sender, LinkButton)
Dim gvrow As GridViewRow = TryCast(lnkbtn.NamingContainer, GridViewRow)
Dim fileid As Integer = Convert.ToInt32(GridView1.DataKeys(gvrow.RowIndex).Value.ToString())
Dim name As String, type As String
Dim con As New SqlConnection("Data Source=BRIAN-PC\SQLEXPRESS;Initial Catalog=master_db;Integrated Security=True;")
con.Open()
Using cmd As New SqlCommand()
cmd.CommandText = "Select content_name, content_type, content_file from content where content_id=#Id"
cmd.Parameters.AddWithValue("#Id", fileid)
cmd.Connection = con
con.Open()
Dim dt As DataTable = GetData(cmd)
If dt IsNot Nothing Then
download(dt)
End If
End Using
End Sub
Public Function GetData(ByVal cmd As SqlCommand) As DataTable
Dim dt As New DataTable
Dim strConnString As String = System.Configuration.ConfigurationManager.ConnectionStrings("ConnStringDb1").ConnectionString()
Dim con As New SqlConnection(strConnString)
Dim sda As New SqlDataAdapter
cmd.CommandType = CommandType.Text
cmd.Connection = con
Try
con.Open()
sda.SelectCommand = cmd
sda.Fill(dt)
Return dt
Catch ex As Exception
Response.Write(ex.Message)
Return Nothing
Finally
con.Close()
sda.Dispose()
con.Dispose()
End Try
End Function
Protected Sub download(ByVal dt As DataTable)
Dim bytes() As Byte = CType(dt.Rows(0)("Data"), Byte())
Response.Buffer = True
Response.Charset = ""
Response.Cache.SetCacheability(HttpCacheability.NoCache)
Response.ContentType = dt.Rows(0)("ContentType").ToString()
Response.AddHeader("content-disposition", "attachment;filename=" & dt.Rows(0)("Name").ToString())
Response.BinaryWrite(bytes)
Response.Flush()
Response.End()
End Sub
gvrow.RowIndex at time of debugging is 0.
Full Code:
Imports System.Data.SqlClient
Imports System.Data
Imports System.IO
Partial Class Documents
Inherits System.Web.UI.Page
Protected Sub btnUploadContent_Click(sender As Object, e As EventArgs) Handles btnUploadContent.Click
Dim filePath As String = FileUpload.PostedFile.FileName
Dim filename As String = Path.GetFileName(filePath)
Dim ext As String = Path.GetExtension(filename)
Dim contenttype As String = String.Empty
Select Case ext
Case ".doc"
contenttype = "application/vnd.ms-word"
Exit Select
Case ".docx"
contenttype = "application/vnd.ms-word"
Exit Select
Case ".xls"
contenttype = "application/vnd.ms-excel"
Exit Select
Case ".xlsx"
contenttype = "application/vnd.ms-excel"
Exit Select
Case ".jpg"
contenttype = "image/jpg"
Exit Select
Case ".png"
contenttype = "image/png"
Exit Select
Case ".gif"
contenttype = "image/gif"
Exit Select
Case ".pdf"
contenttype = "application/pdf"
Exit Select
End Select
If contenttype <> String.Empty Then
Dim fs As Stream = FileUpload.PostedFile.InputStream
Dim br As New BinaryReader(fs)
Dim bytes As Byte() = br.ReadBytes(fs.Length)
'insert the file into database
Dim strQuery As String = "INSERT INTO [master_db].[dbo].[content] ([content_name],[content_type],[content_file]) VALUES (#Name, #ContentType, #Data)"
Dim cmd As New SqlCommand(strQuery)
cmd.Parameters.Add("#Name", SqlDbType.VarChar).Value = filename
cmd.Parameters.Add("#ContentType", SqlDbType.VarChar).Value() = contenttype
cmd.Parameters.Add("#Data", SqlDbType.Binary).Value = bytes
InsertUpdateData(cmd)
lblMessage.ForeColor = System.Drawing.Color.Green
lblMessage.Text = "File Uploaded Successfully"
Else
lblMessage.ForeColor = System.Drawing.Color.Red
lblMessage.Text = "File format not recognised." + " Upload Image/Word/PDF/Excel formats"
End If
End Sub
Protected Sub lnkDownload_Click(ByVal sender As Object, ByVal e As EventArgs)
Dim lnkbtn As LinkButton = TryCast(sender, LinkButton)
Dim gvrow As GridViewRow = TryCast(lnkbtn.NamingContainer, GridViewRow)
Dim fileid As Integer = Convert.ToInt32(GridView1.DataKeys(gvrow.RowIndex).Value.ToString())
Dim name As String, type As String
Dim con As New SqlConnection("Data Source=BRIAN-PC\SQLEXPRESS;Initial Catalog=master_db;Integrated Security=True;")
con.Open()
Using cmd As New SqlCommand()
cmd.CommandText = "Select content_name, content_type, content_file from content where content_id=#Id"
cmd.Parameters.AddWithValue("#Id", fileid)
cmd.Connection = con
con.Open()
Dim dt As DataTable = GetData(cmd)
If dt IsNot Nothing Then
download(dt)
End If
End Using
End Sub
Public Function GetData(ByVal cmd As SqlCommand) As DataTable
Dim dt As New DataTable
Dim strConnString As String = System.Configuration.ConfigurationManager.ConnectionStrings("ConnStringDb1").ConnectionString()
Dim con As New SqlConnection(strConnString)
Dim sda As New SqlDataAdapter
cmd.CommandType = CommandType.Text
cmd.Connection = con
Try
con.Open()
sda.SelectCommand = cmd
sda.Fill(dt)
Return dt
Catch ex As Exception
Response.Write(ex.Message)
Return Nothing
Finally
con.Close()
sda.Dispose()
con.Dispose()
End Try
End Function
Protected Sub download(ByVal dt As DataTable)
Dim bytes() As Byte = CType(dt.Rows(0)("Data"), Byte())
Response.Buffer = True
Response.Charset = ""
Response.Cache.SetCacheability(HttpCacheability.NoCache)
Response.ContentType = dt.Rows(0)("ContentType").ToString()
Response.AddHeader("content-disposition", "attachment;filename=" & dt.Rows(0)("Name").ToString())
Response.BinaryWrite(bytes)
Response.Flush()
Response.End()
End Sub
Public Function InsertUpdateData(ByVal cmd As SqlCommand) As Boolean
Dim strConnString As String = System.Configuration.ConfigurationManager.ConnectionStrings("ConnStringDb1").ConnectionString()
Dim conn As New SqlConnection("Data Source=BRIAN-PC\SQLEXPRESS;Initial Catalog=master_db;Integrated Security=True;")
cmd.CommandType = CommandType.Text
cmd.Connection = conn
Try
conn.Open()
cmd.ExecuteNonQuery()
Return True
Catch ex As Exception
Response.Write(ex.Message)
Return False
Finally
conn.Close()
conn.Dispose()
End Try
End Function
End Class
What is happening and why?

Answer 1

replace the error line with this:
Dim selectedRow As Integer = Me.GridView1.CurrentRow.Index
Dim fileid As Integer = Convert.ToInt32(Me.GridView1.Item(1,gvrow.RowIndex).Value.ToString())
Replace the number 1 with the index of the cell that contains the fileid (ie if its the 0 for the first cell, 1 for the second and so on)
Let me know if this works. Am a C# developer so conversions may differ.

Answer 2

pass the RowIndex via CommandArgument and use it to retrieve the DataKey value
add the below line on Button
CommandArgument='<%# DataBinder.Eval(Container, "RowIndex") %>'
and add the below line on Server Event
Dim Index As Integer = Integer.Parse(e.CommandArgument.ToString())
Dim val As String = DirectCast(Me.grid.DataKeys(Index)("YourDataKeyName"), String)
Update:
See this samples :
sample1
sample 2

Answer 3

I ran into this a while ago myself replacing a predecessors data adapter's with data readers for obvious reasons.
My fix was simple:
if (dt.Rows.Count == 0)
//do stuff
else
//do nothing
GV.DataSource = new DataTable();
you're also loading with a datatable, so that should make deploying it easier.
The reason in your specific case is the exception is thrown when no data is passed to the GV.