Hi Alex,

In your private ticket we discussed a possible solution similar to the one listed here: Filter a Grid Column that is a List.

Generally speaking, the requested feature is valid but it will not cover your use case. The main reason is that you are targeting a column that contains a collection of items. By design, the Grid will render the built-in filter editors only for the column whose FIeld parameters use primitive types.

The Grid will not render a filter menu or an editor in the filter row for the column that contains the list of items. This means that if you need to enable the filtering for this column, you will have to use a Filter Template.

Once the Filter Template is used, the Grid no longer handles the filtering. In this case, it is up to the application to perform the filtering logic. This gives you full flexibility to control how the filtering will happen, so I am not certain what will be the purpose of passing a Function to the FilterDescriptor. Moreover, the FilterDescriptor only supports primitive types for its MemberType field.

Another key point in this scenario is that there is no built-in provision in .NET to filter a collection based on the contents of another collection. Thus, you will need to build a custom filtering logic anyway.

Having the above in mind, I will keep the request to track the interest for the ability to pass a custom Function to the FilterDescriptor. However, for your scenario, the filtering has to be handled with a custom approach as per the linked example.

Regards,
Nadezhda Tacheva
Progress Telerik