Sorting on names (rather than IDs) of fields that are linked into main record

Consider a compound record such as the Item record returned from mod-inventory. The underlying record in inventory-storage has a materialTypeID field; and the compound record adds a {{materialType]} sub-record corresponding to that ID by consulting the material-types data.

That works fine for retrieval: the client can pick out materialType.name to display.

And it works OK for filtering, too: having retrieved the IDs-to-names mapping, the UI uses this to offer filtering where the MT names are displayed, but the query that gets generated when the filter is selected uses the corresponding ID.

But it fails for sorting: there is no way to way to instruct the back-end to sort a list of records by the name of the material-type. materialTypeID exists because it's in the underlying record in mod-inventory, but materialTypeName does not; materialType.name exists in the retrieval record, but not the underlying one used for database operations.

This issue will apply to many "controlled-vocabulary" fields, not just material-type. For example, location and patron-group.