I am using this sample to implement server-side grouping:
Now I need Aggregate sum for the price in the GroupFooterTemplate. When I add aggregates, exceptions are thrown if a group footer uses the aggregate value, if not - the grid simply does not look grouped.
The issue stems from the inability of the System.Text.Json to deserialize interfaces - there are a couple of interfaces in the datasource request and data source result related to aggregates. Preliminary review indicates that perhaps some or all of them might be changed to, for example, Dictionary<string, object> from the current IDictionary<string, object>, or perhaps the framework might "learn" to deserialize interfaces.