Currently, RadGridView does not support data loading on demand when expanding the parent row of a hierarchy level.
As a workaround, you can load the data by using one IList of objects for each level: in your
case the master level
contains Orders IList and child level must
contain OrderItems for all Orders in one IList object. The relation between hierarchy levels is
a necessary condition.
This scenario works for bound and unbound mode. You can view the RadGridView hierarchy example in our QSF for more details.
We are planning to extend this functionality and support on demand loading of data, together with automatic hierarchy generation based on bound hierarchy object.
I hope this was helpful. If you have additional questions, please contact us.
the Telerik team
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