Dropdown list shows first item when page loads

Question

User-460338909 posted

Hi all,

I populate by code a dropdown list with listitems and when the page loads the first item in the dropdown list
is showing. Furthermore the item that is showing in the dropdown list cannot be selected and fire the postback
event. I tried by setting the selectedindex of the dropdown list to -1 but I cannot get it to show nothing in it and
fire the postback event even when I select the first item. Any ideas on what should I do?

Thanks in advance,

/\/ikos

Answer 1

User-993404089 posted

Can you please post some code.There could be several reasons for this?

 

Answer 2

User-460338909 posted

My code is this:

 

Dim lngMaxPeriod As Long
        Using conn As SqlConnection = New SqlConnection(Common.GetConnectionString("KoinoConnectionString"))
            Try
                conn.Open()

                Dim cmndSelect As New SqlCommand("SELECT MAX(PeriodosID) AS MaxPeriodID FROM dbo.[80_Periodoi] " & _
                                                 " GROUP BY PeriodosKoinEkdoth HAVING (PeriodosKoinEkdoth = 1)", conn)
                lngMaxPeriod = cmndSelect.ExecuteScalar()

                hidPeriod.Value = lngMaxPeriod

                cmndSelect.CommandText = "SELECT dbo.[80_Diamerismata].DiamID, dbo.[80_Diamerismata].DiamName, dbo.[80_Enoikoi].EnoikName " & _
                                        "FROM   dbo.[80_Enoikoi] INNER JOIN " & _
                                        " dbo.[90_Diamerismata_Enoikoi] ON dbo.[80_Enoikoi].EnoikID = dbo.[90_Diamerismata_Enoikoi].EnoikID " & _
                                        " RIGHT OUTER JOIN dbo.[80_Diamerismata] ON dbo.[90_Diamerismata_Enoikoi].DiamID = dbo.[80_Diamerismata].DiamID " & _
                                        " WHERE     (dbo.[80_Enoikoi].PeriodosStart <=" & (lngMaxPeriod + 1).ToString & _
                                        " ) AND (dbo.[80_Enoikoi].PeriodosEnd >= " & (lngMaxPeriod + 1).ToString & " )  OR " & _
                                        " (dbo.[80_Enoikoi].PeriodosStart IS NULL) AND (dbo.[80_Enoikoi].PeriodosEnd IS NULL)" & _
                                        " ORDER BY dbo.[80_Diamerismata].DiamID"

                Dim ds As New DataSet
                Dim daSel As New SqlDataAdapter(cmndSelect)

                daSel.Fill(ds, "DiamEnoik")


                If Not Me.IsPostBack Then
                    cmbDiamerisma.Items.Clear()
                End If

                For ii As Integer = 0 To ds.Tables("DiamEnoik").Rows.Count - 1
                    Dim tr As New HtmlTableRow

                    Dim td1 As New HtmlTableCell
                    td1.Attributes.Add("style", "font-style:italic; font-size:14px")
                    td1.InnerText = ds.Tables("DiamEnoik").Rows(ii).Item("DiamName")

                    If Not Me.IsPostBack Then
                        Dim li As New ListItem
                        li.Text = ds.Tables("DiamEnoik").Rows(ii).Item("DiamName")
                        li.Value = ds.Tables("DiamEnoik").Rows(ii).Item("DiamID")
                        cmbDiamerisma.Items.Add(li)
                    End If

                    tr.Cells.Add(td1)

                    Dim td2 As New HtmlTableCell
                    td2.Attributes.Add("style", "font-style:italic; font-size:14px; width:200px")
                    td2.InnerText = IIf(ds.Tables("DiamEnoik").Rows(ii).Item("EnoikName").Equals(DBNull.Value), "Δεν έχει συμπληρωθεί", _
                                    ds.Tables("DiamEnoik").Rows(ii).Item("EnoikName"))

                    tr.Cells.Add(td2)

                    tblDiamEnoikoi.Rows.Add(tr)

                Next


                ds.Dispose()
                daSel.Dispose()
                cmndSelect.Dispose()
                conn.Close()
            Catch ex As Exception

                If conn.State = Data.ConnectionState.Open Then conn.Close()
            End Try
        End Using

cmbDiamerisma is the dropdown list. Common is a module in App_Code that has some common shared functions.

Answer 3

User-460338909 posted

I have to add that when I select another item in the dropdown list, the postback event occurs and then I can select the first item. But when there is only one item in the list then it gets very tricky... I can't think of nothing else to do!

Answer 4

User1256425868 posted

You can add one more Item in your Dropdown after adding all the items fron database.

Dim li As New ListItem
li.Text = "Select"
li.Value = "0"
cmbDiamerisma.Items.Insert(0,li)

Show every time you will get "Select" as first item on your dropdown list.

Answer 5

User-993404089 posted

Are you trying to populate the dropdown with a list of values on the load and then when a user changes the item in the drop down then you want to fire a postback to the server?

If so can you provide the html section that has your dropdown control.

Answer 6

User-1225287840 posted

Try adding the below code (cmbDiamerisma.DataBind()),

Next

cmbDiamerisma.DataBind() 

ds.Dispose()
daSel.Dispose()
cmndSelect.Dispose()

Answer 7

User-460338909 posted

Yes the code I embeded bellow is in the Page_Load event. The HTML for the Dropdownlist is as follows:

 

                    <table>
                        <tr>
                            <td class="style7">
                                <span style = "color:Red; font-size:14px; font-weight:bold  "> Διαμέρισμα </span> 
</td>
                            <td align = "left" >
                    
                                    <asp:DropDownList ID="cmbDiamerisma" runat="server" AutoPostBack="True" 
                                        Height="16px" Width="61px">
                                    </asp:DropDownList> 
                                &nbsp;</td>
                        </tr>

 

I manage then the cmbDiamerisma_SelectedIndexChanged event.

Answer 8

User-460338909 posted

That is a very good suggestion MDubey1987. I might do that if I do not get it done otherwise. Thanks!!!

Answer 9

User2049726087 posted
You have to write the binding code as given below within page load event If(! IsPostback) { // code for binding drop down }

Answer 10

User-1961616419 posted

read the properly working article on: How to fill DropDownList from Sql server database in asp.net

Answer 11

User-782344923 posted

Hi buddy,

Place your Dropdown list binding code in not postback tag as

protected void Page_Load(object sender, eventargs e)
{
    if (!IsPostBack) // Means page is loading first time and on cause post back this condtion is fire
    {
        // Place your binding dropdownlist code here
    }
}

Hope you understand the concept.

Cheers