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Datagrid bound to CollectionBase class doesn't use Enumerator!


I'm trying to write a PageableCollection class which implements paging for
me so I don't need to rely on the paging provided by the DataGrid as that
generates huge viewstate when bound to a collection with a lot of items.

The code below works fine when I use foreach to iterate over it but when I
bind the Datagrid to an instance of this class I get the whole collection
displayed in the grid! Does the Datagrid not use GetEnumerator to obtain an
enumerator? I've also tried overriding the indexer and count properties of
the collection with no success.

Is the DataGrid doing something cheesy with Reflection in the case of being
bound to a class derived from CollectionBase to get directly at the
InnerList inside the collection?

Anybody got any idea what is going on here?

Code follows:

public class PageableCollection : CollectionBase
private bool fAllowPaging;
private int fPageSize;
private int fCurrentPage;

public int CurrentPage
get { return fCurrentPage; }
set { fCurrentPage = value; }

public bool AllowPaging
get { return fAllowPaging; }
set { fAllowPaging = value; }

public int PageSize
get { return fPageSize; }
set { fPageSize = value; }

public int PageCount
return ((Count % fPageSize) == 0) ? (Count / fPageSize) : ((Count /
fPageSize) + 1);

public PageableCollection()
fAllowPaging = false;
fPageSize = 20;
fCurrentPage = 1;

public new IEnumerator GetEnumerator()
if (!fAllowPaging)
return base.GetEnumerator();
int index = ((fPageSize * fCurrentPage) - fPageSize);
int count = fPageSize;

if ((count + index) > Count)
count = Count - index;

return InnerList.GetEnumerator(index, count);
Nov 15 '05 #1
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