Requiring data_mapper pulls in unnecessary dependencies. All that's truly needed is dm-core and dm-aggregates (which is already required).
Use dm-core instead of data_mapper to detect DataMapper
This adds no extra value, some apps may already require the rest of data_mapper, so lets just leave it until the next major release.
We plan to refactor to gems.
The reason for this change is that one gem I require conflicts with dm-serializer, which data_mapper pulls in automatically. Changing this to requiring dm-core allows me to use kaminari.
@jlukas can you show us your code, or a reproducible example?
The conflict is documented here: