Question

I am developing a VB.NET ASPX file which is currently working. But now it errors cause I added this one new input parameter which is a dropdownlist. The dropdownlist works properly now. Its source comes from a SQL DataReader. But hte problem is that the fields that the user should see are different from underlying values. So I want to create a 2 dimensional array list or somehow create a mapping as follows:
Visible Text Invisible Value
AAAAA 601
BBBBB 602
CCCCC 603
…

So the user should just see AAAAA, BBBBB, CCCCC, etc. as choices. But then if they choose “BBBBB”, my SQL query must filter records on field = 602.

Here is excerpt of my code now:

        Dim pcSQL As String
        Dim ProductList As New ArrayList()
        Dim ProdCodeSearch As String
        Dim InstrumentSearch As String

        pcSQL = " select distinct instrument_name, product_code from FRUD.tblXref order by instrument_name "
        Dim DBConn As SqlConnection
        DBConn = New SqlConnection(ConfigurationManager.AppSettings("AMDMetricsConnectionString"))
        DBConn.Open()
        Dim reader As SqlDataReader
            Dim DBCommand As New SqlCommand(pcSQL, DBConn)       
        reader = DBCommand.ExecuteReader()

        While reader.Read()
        ProductList.Add(reader(0),reader(1))
        End While

        dProdCodeSearch.DataSource = ProductList(0)
        dProdCodeSearch.DataBind()
        reader.Close()

        ProdCodeSearch = dProdCodeSearch.SelectedValue

Answer 1

You have to set the DataTextField and the DataValueField of the DropDownList before you DataBind it.

dProdCodeSearch.DataSource = reader
dProdCodeSearch.DataTextField  = "instrument_name"
dProdCodeSearch.DataValueField = "product_code"     
dProdCodeSearch.DataBind()

The DataTextField is the column that you want the user to see and the DataValueField normally is the primary-key column.

You need the DropDownList’s SelectedValue to get the identifier of the selected item.