DropDownList drops values on window resize?

  • Thread starter Thread starter Lionel Slade
  • Start date Start date
L

Lionel Slade

Hi,

I've bound some drop down lists to a dataset, but if the
iexplorer window is resized the contents of the lists are
lost?

Why is this happening?

AutoPostback is set to true.

TAI

Lionel
 
The function is a generic one where you can pass the
table name and field name to populate the
The code used to populate the list is:

Private Function PopulateDropDownListbox2(ByVal iField As
String, _
ByVal iTable As String, _
ByVal iDDL As DropDownList, _
ByVal iConnection As ADODB.Connection, _
Optional ByVal iDistinct As Boolean = True, _
Optional ByVal iAdditionalQuery As String = "")
As System.Data.DataSet

' Create a recodset from the Connection, use
distinct if required
Dim recs As New ADODB.Recordset, sql As String
If iDistinct = True Then
sql = "Select Distinct " & iField & " from "
& iTable
Else
sql = "Select " & iField & " from " & iTable
End If

' Apply a filter string
If iAdditionalQuery = "" Then
' do nothing
Else
sql = sql & " WHERE " & iAdditionalQuery
End If

' Query the connection
recs = iConnection.Execute(sql)

' Populate a tempory data table and data adapter
Dim dt As New DataTable
Dim da As New System.Data.OleDb.OleDbDataAdapter
da.Fill(dt, recs)

' Create a dataset
Dim ds As New DataSet
ds.Tables.Add(dt)

' Populate and update the Drop Down Listbox
iDDL.DataTextField = iField
iDDL.DataSource = ds.Tables(0)
iDDL.DataBind()

Return ds

' Clear Up
recs = Nothing
dt = Nothing
da = Nothing
ds = Nothing

End Function
 
Hi,

I tried your code and changed it a lot.
I made from it in a workingsample situation but had to change a lot.
(It is still not what I would make, but I did not want to change to much
from your originalcode)
I also used sqlclient.sql........ that you can everywhere change in
oledb.oledb....... and then use the right connection string.

I did use the northwind database because I have of course not your database
and therfore I had to remove some things.

Under the sample I give some comments on your code.

I hope this helps?

Cor

\\\
Private Sub Page_Load(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles MyBase.Load
If Not IsPostBack Then
Dim Conn As New SqlClient.SqlConnection _
("Server=xxxxxxx;DataBase=northwind;Integrated Security=SSPI")
PopulateDropDownListbox2("EmployeeID", "Employees",
DropDownList1, Conn, True, )
End If
End Sub

Private Function PopulateDropDownListbox2 _
(ByVal iField As String, _
ByVal iTable As String, _
ByVal iDDL As DropDownList, _
ByVal iConnection As SqlClient.SqlConnection, _
Optional ByVal iDistinct As Boolean = True, _
Optional ByVal iAdditionalQuery As String = "") As
System.Data.DataSet
' Create a recodset from the Connection, use distinct if required
Dim sql As String = "Select EmployeeID, FirstName from Employees"
Dim ds As New DataSet
Dim da As New SqlClient.SqlDataAdapter(sql, iConnection)
da.Fill(ds, iTable)
' Populate and update the Drop Down Listbox
iDDL.DataTextField = iField
iDDL.DataValueField = "Firstname"
iDDL.DataSource = ds.Tables(0)
iDDL.DataBind()
' Clear Up
iConnection.Close()
Return ds
End Function
Private Sub Button1_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Button1.Click
Label1.Text = Me.DropDownList1.SelectedValue
End Sub
End Class
///
Private Function PopulateDropDownListbox2(ByVal iField As
String, _
ByVal iTable As String, _
ByVal iDDL As DropDownList, _
ByVal iConnection As ADODB.Connection, _
Optional ByVal iDistinct As Boolean = True, _
Optional ByVal iAdditionalQuery As String = "")
As System.Data.DataSet
Click to expand...

Why you make this difficult function. The most important thing the sql
string is not in it, when that was I could understand it, but than you do
not need that two last optional parameters.
' Create a recodset from the Connection, use
distinct if required
Dim recs As New ADODB.Recordset, sql As String
Click to expand...

Why you need a recordset you are not using it and set it even to nothing at
the end
If iDistinct = True Then
sql = "Select Distinct " & iField & " from "
& iTable
Else
sql = "Select " & iField & " from " & iTable
End If

' Apply a filter string
If iAdditionalQuery = "" Then
' do nothing
Else
sql = sql & " WHERE " & iAdditionalQuery
End If
Click to expand...

See for that my first comment
' Query the connection
recs = iConnection.Execute(sql)

' Populate a tempory data table and data adapter
Dim dt As New DataTable
Dim da As New System.Data.OleDb.OleDbDataAdapter
da.Fill(dt, recs)
Click to expand...

You have to file a dataset, just change dt for ds and datatable for datset
but see my code to do it right there are more errors in that
' Create a dataset
Dim ds As New DataSet
ds.Tables.Add(dt)
Click to expand...
See before and my code
' Populate and update the Drop Down Listbox
iDDL.DataTextField = iField
iDDL.DataSource = ds.Tables(0)
iDDL.DataBind()

Return ds

' Clear Up
recs = Nothing
dt = Nothing
da = Nothing
ds = Nothing
Click to expand...

Why is all that setting to nothing I see it nowhere in the documentation

There is no close of the connection.
 
Thanks for that, I change the code to use OleDB. This
makes the connection and populates the ddl fine in the
first instance (as did the original code). So, the
problem isn't populating the list in the first place,
but, when the explorer window is resized, the ddl loses
all its values, i.e. the ddl goes blank?

Any more ideas?
 
-----Original Message-----
Thanks for that, I change the code to use OleDB. This
makes the connection and populates the drop down list fine in the
first instance (as did the original code). So, the
problem isn't populating the list in the first place,
but, when the explorer window is resized, the drop down list loses
all its values, i.e. the drop down list goes blank?

Any more ideas?
.
Click to expand...
 
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