If I have an ObjectDataSource defined at design time, can I get a DataTable from that ObjectDataSource at runtime? I have a method that returns a DataTable that I am using for
Yes, but you need to pay attention to when that item has been bound.
If you are talking about a web page:
If you tried to access the DataSource (in your case DataTable) before the page has loaded, it will be null.
If you tried to access it after it has been bound, you'd be able to use the object.
I don't really understand your question... are you asking if the object you define in the ObjectDataSource can return a DataTable in the configured select method? Yes, I do it all the time. You can also examine the returned DataTable in the OnSelected event (it is the ReturnValue property of the event object).