We have a problem setting, actually resetting, the SelectedItemTem plate
of a DataList control. Below is the ObjectDataSourc e and the DataList
in .ASPX:
<asp:ObjectData Source ID="mySource" runat="server"
SelectMethod="G etStageUsage" TypeName="SomeC ontroller">
</asp:ObjectDataS ource>
<asp:DataList ID="dl" runat="server"
DataSourceID="m ySource" DataKeyField="I D"
OnItemCommand=" dl_ItemCommand" >
<HeaderTemplate >...</HeaderTemplate>
<ItemTemplate>. ..</ItemTemplate>
<SelectedItemTe mplate>...</SelectedItemTem plate>
</asp:DataList>
The ID column has a LinkButton with CommandName="Se lect" set. Now, when
we select a certain row, we want to show the SelectedItemTem plate.
Therefore we used the OnItemCommand event. See code below. We used this
code to check if we need to show or hide the SelectedItemTem plate (ie.
show hide details of that item in the grid). When the details for an
item are already shown, and we select it again, the details must hide
(ie. collapse).
protected void dl_ItemCommand( object source, DataListCommand EventArgs
e)
{
DataList fromList = (DataList)sourc e;
if (e.CommandName == "Select")
{
if (fromList.Selec tedIndex == e.Item.ItemInde x)
{
fromList.Select edIndex = -1;
}
else
{
fromList.Select edIndex = e.Item.ItemInde x;
}
// Rebind the datasource to the datalist
fromList.DataBi nd();
}
}
In this example we check if the CommandName is "Select" and check
to show or hide the SelectedItemTem plate. Now, when we select an item,
the SelectedItem opens (as expected). When we want to hide/collapse the
details we set the SelectedIndex op -1. However, it does not behave as
it "should". The SelectedIndex is set to -1, but on a PostBack it
has the value again of the e.Item.Index. Therefore, it always goes
setting the value to -1, instead of reopening it again (btw; when we
select a other item it opens because the e.Item.Index has another
value).
Finally we found a workaround, and we're not sure if this is the way
to go. We disabled the ViewState of the DataList (dl) in the .ASPX.
Then we changed the ItemCommand event into the code below. Notice that
we changed the check of the fromList to our own ViewState:
protected void dl_ItemCommand( object source, DataListCommand EventArgs
e)
{
DataList fromList = (DataList)sourc e;
if (e.CommandName == "Select")
{
if (Convert.ToInt3 2(ViewState["selectedItemIn dex"]) ==
e.Item.ItemInde x)
{
fromList.Select edIndex = -1
ViewState["selectedItemIn dex"] = -1;
}
else
{
fromList.Select edIndex = e.Item.ItemInde x;
ViewState["selectedItemIn dex"] = e.Item.ItemInde x;
}
// Rebind the datasource to the datalist
fromList.DataBi nd();
}
This does do the trick, but we're not sure if this is a good
practice? Any thoughts?
Thanks,
Jules
