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Post Back Wiping Out Dependent Drop Downs
Joined: 13 Jan 2005
Posts: 1
Post Back Wiping Out Dependent Drop Downs
I have 3 dependent drop down menus populated by stored procedures.
Menu 2 and 3 are based on the first selection.
If I code and stop and just using first two menus, everything is fine,
but if I tried to tack on the same logic to the third menu it
malfunctions. The third menu will not populate the first time you hit
the page, and dies if you go back to "Select a class" (index)
How can I get a third menu to work? Thanks
Here is my code:
Sub Page_Load(s As Object, e As EventArgs)
If Not Page.IsPostBack Then
Dim MyConnection As SqlConnection = new
SqlConnection(ConfigurationSettings.AppSettings("S
QLServerConnection"))
Dim MyCommand As SqlCommand = New SqlCommand()
With MyCommand
.Connection = MyConnection
.CommandText = "selClasses"
.CommandType = CommandType.StoredProcedure
End With
Dim MyDataReader As SqlDataReader
Try
MyConnection.Open()
MyDataReader = myCommand.ExecuteReader(CommandBeha
vior.CloseConnection)
ListClassN.DataSource = MyDataReader
ListClassN.DataBind()
Catch myException As Exception
Response.Write("An error has occurred: " & myException.ToString())
Finally
If Not MyDataReader is Nothing Then
MyDataReader.Close()
End If
ListClassN.Items.Insert(0, "Select a class")
ListClassN.SelectedIndex = 0
End Try
End If
End Sub
//HERE IS THE SECOND MENU. THIS WORKS
Sub ClassN_change(s As Object, e As EventArgs)
If Page.IsPostBack Then
Dim MyConnection As SqlConnection = new
SqlConnection(ConfigurationSettings.AppSettings("S
QLServerConnection"))
Dim MyCommand As SqlCommand = New SqlCommand("proc_selClassDate3",
MyConnection)
MyCommand.CommandType = CommandType.StoredProcedure
Dim clnameParam As SqlParameter = MyCommand.Parameters.Add _
("@clname", SqlDbType.VarChar, 200)
clnameParam.Direction = ParameterDirection.Input
clnameParam.Value = ListClassN.SelectedItem.Text
Dim MyDataReader As SqlDataReader
Try
MyConnection.Open()
MyDataReader = myCommand.ExecuteReader(CommandBeha
vior.CloseConnection)
ClassD.DataSource = MyDataReader
ClassD.DataBind()
Catch myException As Exception
Response.Write("An error has occurred: " & myException.ToString())
Finally
If Not MyDataReader is Nothing Then
MyDataReader.Close()
End If
ClassD.Items.Insert(0, "Select a date")
ClassD.SelectedIndex = 0
End Try
End If
End Sub
//OK TO HERE this is the third drop down. Everything hits the fan.
Sub location_change(s As Object, e As EventArgs)
If Page.IsPostBack Then
Dim MyConnection As SqlConnection = new
SqlConnection(ConfigurationSettings.AppSettings("S
QLServerConnection"))
Dim MyCommand As SqlCommand = New SqlCommand("Location", MyConnection)
MyCommand.CommandType = CommandType.StoredProcedure
Dim clnameParam As SqlParameter = MyCommand.Parameters.Add _
("@clname", SqlDbType.VarChar, 200)
clnameParam.Direction = ParameterDirection.Input
clnameParam.Value = ListClassN.SelectedItem.Text
Dim MyDataReader As SqlDataReader
Try
MyConnection.Open()
MyDataReader = myCommand.ExecuteReader(CommandBeha
vior.CloseConnection)
ListLocation.DataSource = MyDataReader
ListLocation.DataBind()
Catch myException As Exception
Response.Write("An error has occurred: " & myException.ToString())
Finally
If Not MyDataReader is Nothing Then
MyDataReader.Close()
End If
ListLocation.Items.Insert(0, "Select a location")
ListLocation.SelectedIndex = 0
End Try
End If
End Sub
</script>
<body>
<form runat="server">
<asp:DropDownList id="ListClassN"
Datatextfield="clname"
DataValueField="classid" onSelectedIndexChanged="ClassN_change"
runat="server" AutoPostBack="True" />
<asp:DropDownList id="ClassD"
DataValueField="classid" onSelectedIndexChanged="location_change"
DataTextField="date"
runat="server" />
<asp:DropDownList id="ListLocation"
DataValueField="classid" DataTextField="location"
runat="server" />
</form>
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