I would like to create a nested datalist inside the
selecteditemtem plate of a datalist. My hope is that when a user clicks
on a link a set of child links is displayed. For example if the user
clicks men's clothing he would get a list of sub categories like pants,
shirts, shorts etc
I have put together the following and I get the original datalist fine.
When I try to get the sublist I get the following error: Object
reference not set to an instance of an object.
The offending line is
brandSubList.Da taSource = Catalog.GetSubC atsInBrands(Bra ndID)
from the code behind listed below.
---------------------------------
HTML code looks like this:
<asp:datalist id="brandList" Runat="server">
<ItemTemplate >
<DIV class="navcells "><B>
<asp:hyperlin k id="brandLink" Runat="server" NavigateUrl= '<%#
"../default.aspx?br andID=" & databinder.eval (container.data item,
"strBrandCo de") %>' text= '<%# DataBinder.Eval ( Container.DataI tem,
"strBrandNa me" ) %>' >
</asp:hyperlink></B></DIV>
</ItemTemplate>
<SelectedItemTe mplate>
<asp:DataList id="brandSubLis t" Runat="server">
<ItemTemplate>< DIV class="navcells "><B>
<asp:LinkButt on id="brandsubLin k" Runat="server"
CommandName="se lect"><%# DataBinder.Eval ( Container.DataI tem,
"strSubCategory " ) %>
</asp:LinkButton> </B></DIV>
</ItemTemplate>
</asp:DataList>
</SelectedItemTem plate>
</asp:datalist>
---------------------------------------------------------
My code behind looks like this:
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArg s) Handles MyBase.Load
Dim BrandID As String = Request.QuerySt ring("brandID")
brandList.DataS ource = Catalog.GetBran ds()
brandList.DataB ind()
If Not BrandID Is Nothing Then
Dim BrandSublist As DataList
brandSubList.Da taSource =
Catalog.GetSubC atsInBrands(Bra ndID)
brandSubList.Da taBind()
End If
--------------------------------------------------------
Data is pulled from a business objects doc like this
Public Shared Function GetBrands() As SqlDataReader
'Create connetion objedt
Dim Connection As New SqlConnection(c onnectionString )
'Create and initialize the command Object
Dim command As New SqlCommand("New _GetBrands", Connection)
command.Command Type = CommandType.Sto redProcedure
'Open the connection
Connection.Open ()
'Return a SqlDatatreader
Return command.Execute Reader(CommandB ehavior.CloseCo nnection)
End Function
Public Shared Function GetSubCatsInBra nds(ByVal brandID As String) As
SqlDataReader
'create the connection string
Dim connection As New SqlConnection(c onnectionString )
'Create and initialize the command Object
Dim command As New SqlCommand("New _getSubCatsInBr ands",
connection)
command.Command Type = CommandType.Sto redProcedure
'Add an input parameter and suply a valiue for it
command.Paramet ers.Add("@brand ID", SqlDbType.NVarC har, 5)
command.Paramet ers("@brandID") .Value = brandID
'Open the connection, exectue the command, and clost the
connection
Try
connection.Open ()
command.Execute NonQuery()
Finally
connection.Clos e()
End Try
