DataList
The DataList is very much like the Repeater but
the DataList supports editing of data. You use the templates like we did with
the repeater, but there are two new ones :
- SelectedItemTemplate. This is the
template the shows up when you select a row.
- EditItemTemplate. This is what shows
up when you select a row for editing.
Here is a very simple use of it.
dl.DataSource =
ds.Tables("users").DefaultView
Databind()
End SubSub
dl_ItemCommand(sender as object, e as DataListCommandEventArgs)
dl.SelectedIndex = e.Item.ItemIndex
dl.DataBind()
End Sub
</script>
<html><body><font face="arial"
size="2"><form runat="server">
<asp:datalist id="dl" runat="server"
HeaderStyle-BackColor="#6699FF"
SelectedItemStyle-BackColor="#6666FF"
SelectedItemStyle-ForeColor="#FFFFFF"
RepeatLayout = "table"
RepeatDirection = "vertical"
DataKeyField = "ID"
OnItemCommand="dl_ItemCommand">
<HeaderTemplate>
Last Name, click for full name.
</HeaderTemplate>
<ItemTemplate>
<asp:linkbutton id="b1" runat="server" Text='<%#
Container.DataItem("LName") %>' CommandName = "select" />
<br>
</ItemTemplate>
<SelecteditemTemplate>
<%# Container.DataItem("LName") & ", " &
Container.DataItem("FName") %>
<br>
</SelectedItemTemplate>
</asp:datalist>
</form></font>
</body>
</html> |
This is a rather large piece of code, but here
is the explanation....
- After the databinding we put a new procedure
(this will be explained soon).
- We enclose the DataList in a form tag
because it needs to reload the page to select items.
- We define properties of the DataList -
- HeaderStyle-BackColor The
background of the Header (instead of putting it in the table code).
- SelectedItem-BackColor The
background of the Selected Item.
- RepeatLayout This is how the
DataList should be laid out - either 'table' or 'flow' (flow is just
nothing ie. You define exactly how you want it.)
- RepeatDirection The direction in
which to display the items (horizontal or vertical).
- DataKeyField The primary key to
use, this helps when selecting and editing data.
- OnItemCommand Explained Later.
- HeaderTemplate This is just a very
simple Header column.
- ItemTemplate The link button is a
link that serves as a submit type button (but text-only). You display the
Last Name and the CommandName of "Select" sends the command "Select" to the
DataList (which then performs whatever it needs to do.
- SelectedItemTemplate Shows the First
and Last Name.
- Then we close up everything
This is quite complicated and there are many
unexplained things, here is an explanation for one of them :
Most of these controls have events that happen
when you do something, like when you click on an item or automatic ones like
when an item is created. All of these events can have event handlers. In the
above example we used an event handler for the ItemCommand event. It takes in
the usually parameters with one difference - its DataListCommandEventArgs and
not EventArgs, this provides you with more properties that are specialized for
use with the DataList.
dl.SelectedIndex tells the DataList what Item
to put the selected template on.
e.Item.ItemIndex returns the index of the Item that was selected.
There are many more events for Data Viewers and
I hope to provide them in a future part.
But that wraps up the DataList, don't be afraid
to experiment with properties and ways to view data.
