Using Eval function in my code behind? - asp.net

Question

Here's my code:
Partial Class VideoPlayer
Inherits System.Web.UI.Page
Protected strFileName As String
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
Dim con As New OleDbConnection
Dim dbProvider As String
Dim dbSource As String
Dim vidID As Integer = Integer.Parse(Request.QueryString("ID"))
dbProvider = "PROVIDER=Microsoft.Jet.OLEDB.4.0;"
dbSource = "Data Source = |DataDirectory|/webvideos.mdb"
con.ConnectionString = dbProvider & dbSource
con.Open()
Dim strSQL As String = "SELECT * FROM Videos WHERE ID=" & vidID
strFileName = "videos/TrainingVideos/" & Eval("Filename")
con.Close()
End Sub
End Class
So when I run the code, it tells me it can't run Eval on my string. What am I missing?

Answer 1

Eval will work in your .aspx code with a DataBoundControl.
When in code-behind, you are setting up the connectionstring, sql query and other variables but you are not actually executing the query.
So your code should be something like below:
Dim con As New OleDbConnection
Dim dbProvider As String
Dim dbSource As String
Dim vidID As Integer = Integer.Parse(Request.QueryString("ID"))
dbProvider = "PROVIDER=Microsoft.Jet.OLEDB.4.0;"
dbSource = "Data Source = |DataDirectory|/webvideos.mdb"
con.ConnectionString = dbProvider & dbSource
con.Open()
Dim strSQL As String = "SELECT * FROM Videos WHERE ID=" & vidID
//Create an OleDbCommand object.
//Pass in the SQL query and the OleDbConnection object
Dim cmd As OleDbCommand = New OleDbCommand(strSQL, con)
//Execute the command
Dim reader As OleDbDataReader = cmd.ExecuteReader
//Read the first record from the reader
reader.Read()
strFileName = "videos\TrainingVideos\" & reader(1)
con.Close()

Answer 2

First the most important, you are open for sql-injection here:
"SELECT * FROM Videos WHERE ID=" & vidID
Use sql-parameters instead.
You can use Eval only in a databinding context. So you need to call Me.DataBind before.
Me.DataBind()
Dim fileName = Me.Eval("Filename").ToString()
strFileName = System.IO.Path.Combine("videos/TrainingVideos", fileName)
However, i don't know what you're actually trying to achieve here. Why do you need it at all?
Global variable, forgot to add it up there.
Then access it directly.