DataList and ItemTemplate

[Guest]

I am trying to use a DataList and the ItemTemplate.

I am binding the Datalist to a SQL query that gives me a list of Items with
a Parent Category.

I want to loop through all the items, but only print the Parent Category
once, regardless of how many child items are in it.

So my perfect output would look something like:

Category A
Item 1
Item 2
Item 3

Category B
Item 1

Category C
Item 1
Item 2


Can I use the ItemTemplate to produce this type of output?

I know that I can easily get this type of output
Category A
Item 1

Category A
Item 2

Category A
Item 3

Category B
Item 1

Category B
Item 2

Category C
Item 1
....

It does not appear that I can embed ASP code within the ItemTemplate tags?
If I try, then it says that I have not declared the Container object, which
holds the Item and Category values.

Am I missing something easy here?

 

[Guest]

Hello Paul,

If I were you, I'd look at the ItemDataBound event for the datalist. I do
something similar for a blog I keep. I want to list the blog entry and
any/all comments:

blogentry1
comment1
comment2
blogentry2
comment3
comment4

While it's not the exact same situation as you have since the comments are
uniquely tied to a blogentry, it's similar.

In the ItemDataBound event, you can get your categoryid and then look up any
item(s) which may belong to it. Something along these lines:
=-=-=-=-=-=-
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType ==
ListItemType.AlternatingItem)
{
Label lbl = (System.Web.UI.WebControls.HyperLink)
e.Item.FindControl("lblCategory");
if (lbl != null)
{
... find any items which match this category and list them
}

}
=-=-=-=-=-
A deeper explanation of the ItemDataBound event with a sample can be found at
http://www.codeproject.com/aspnet/ItemCreated.asp. Or do a search in google:
http://www.google.com/search?hl=en&q=itemdatabound for more.

 

[Guest]

Hi Paul,

The better way to achieve it is to use another list control (DataList,
DataGrid, or Repeater) nested in the DataList. In outer DataList, it loops
thru Categories. And in the inner list control, it binds a data source with
Items associated with a Category.

HTH

Elton Wang

 

[Guest]

Thanks for this.

Is there an code example of nested DataLists anyplace? A code example of a
nested DataList that uses a value from the outer Datalist?

 

[Guest]

Following code is not tested:

<aspataList id="CategoryList" runat="server" RepeatDirection=Vertical>
<ItemTemplate>
Category: <%# DataBinder.Eval(Container.DataItem,
"Category_Field_Name") %><br>
<aspataList ID="ItemList" Runat=server
RepeatDirection=Vertical>
<ItemTemplate>
<%# DataBinder.Eval(Container.DataItem,
"Item_Field_Name") %>
</ItemTemplate>
</aspataList>
</ItemTemplate>
</aspataList>


In CategoryList_ItemDataBound

if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType ==
ListItemType.AlternatingItem)
{
// Suppose you use DataTable, or DataView, or DataSet as Data Source
DataRowView drv = (DataRowView)e.Item.DataItem;
string Category = drv["Category_Field_Name"].ToString();
DataTable itemTable = GetItems(Category);
DataList itemList = (DataList)e.Item.FindControl("ItemList");
itemList.DataSource = itemTable;
itemList.DataBind();
}

HTH

Elton Wang

 

[Guest]

Thank you for this. I may be getting closer.

The problem with this is that each DataList is databinded to a SQL query
(which you do not show here). The DataSource is a DataReader object.

The inner DataList is binded to a SQL query that uses a value from the outer
DataList. (i.e. select * from items where category = x).

So I am not sure how the inner DataList could be dynamic in that sense.

Also, I use VB.Net, not C. So I am unsure what C's "In" statement equivalent
is in VB?

TIA.

Following code is not tested:

<aspataList id="CategoryList" runat="server" RepeatDirection=Vertical>
<ItemTemplate>
Category: <%# DataBinder.Eval(Container.DataItem,
"Category_Field_Name") %><br>
<aspataList ID="ItemList" Runat=server
RepeatDirection=Vertical>
<ItemTemplate>
<%# DataBinder.Eval(Container.DataItem,
"Item_Field_Name") %>
</ItemTemplate>
</aspataList>
</ItemTemplate>
</aspataList>


In CategoryList_ItemDataBound

if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType ==
ListItemType.AlternatingItem)
{
// Suppose you use DataTable, or DataView, or DataSet as Data Source
DataRowView drv = (DataRowView)e.Item.DataItem;
string Category = drv["Category_Field_Name"].ToString();
DataTable itemTable = GetItems(Category);
DataList itemList = (DataList)e.Item.FindControl("ItemList");
itemList.DataSource = itemTable;
itemList.DataBind();
}

HTH

Elton Wang

Thanks for this.

Is there an code example of nested DataLists anyplace? A code example of a
nested DataList that uses a value from the outer Datalist?

 

[Guest]

In CategoryList_ItemDataBound

If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType =
ListItemType.AlternatingItem Then
' Since you use DataReader as datasource, using
' System.Data.Common.DbDataRecord
Dim record As System.Data.Common.DbDataRecord =
CType(e.Item.DataItem, System.Data.Common.DbDataRecord)
Dim strCategory As String = record
..Item("Category_Field_Name").ToString
Dim itemTable As DataTable = GetItems("Select Item From tabl_name
Where Category = '" + strCategory + "'")
Dim itemList As Datalist = CType(e.Item.FindControl("ItemList"),
DataList)
itemList.DataSource = itemTable
itemList.DataBind()
End If

Thank you for this. I may be getting closer.

The problem with this is that each DataList is databinded to a SQL query
(which you do not show here). The DataSource is a DataReader object.

The inner DataList is binded to a SQL query that uses a value from the outer
DataList. (i.e. select * from items where category = x).

So I am not sure how the inner DataList could be dynamic in that sense.

Also, I use VB.Net, not C. So I am unsure what C's "In" statement equivalent
is in VB?

TIA.

Following code is not tested:

<aspataList id="CategoryList" runat="server" RepeatDirection=Vertical>
<ItemTemplate>
Category: <%# DataBinder.Eval(Container.DataItem,
"Category_Field_Name") %><br>
<aspataList ID="ItemList" Runat=server
RepeatDirection=Vertical>
<ItemTemplate>
<%# DataBinder.Eval(Container.DataItem,
"Item_Field_Name") %>
</ItemTemplate>
</aspataList>
</ItemTemplate>
</aspataList>


In CategoryList_ItemDataBound

if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType ==
ListItemType.AlternatingItem)
{
// Suppose you use DataTable, or DataView, or DataSet as Data Source
DataRowView drv = (DataRowView)e.Item.DataItem;
string Category = drv["Category_Field_Name"].ToString();
DataTable itemTable = GetItems(Category);
DataList itemList = (DataList)e.Item.FindControl("ItemList");
itemList.DataSource = itemTable;
itemList.DataBind();
}

HTH

Elton Wang

Thanks for this.

Is there an code example of nested DataLists anyplace? A code example of a
nested DataList that uses a value from the outer Datalist?




:

Hi Paul,

The better way to achieve it is to use another list control (DataList,
DataGrid, or Repeater) nested in the DataList. In outer DataList, it loops
thru Categories. And in the inner list control, it binds a data source with
Items associated with a Category.

HTH

Elton Wang


:

I am trying to use a DataList and the ItemTemplate.

I am binding the Datalist to a SQL query that gives me a list of Items with
a Parent Category.

I want to loop through all the items, but only print the Parent Category
once, regardless of how many child items are in it.

So my perfect output would look something like:

Category A
Item 1
Item 2
Item 3

Category B
Item 1

Category C
Item 1
Item 2


Can I use the ItemTemplate to produce this type of output?

I know that I can easily get this type of output
Category A
Item 1

Category A
Item 2

Category A
Item 3

Category B
Item 1

Category B
Item 2

Category C
Item 1
...

It does not appear that I can embed ASP code within the ItemTemplate tags?
If I try, then it says that I have not declared the Container object, which
holds the Item and Category values.

Am I missing something easy here?