I have a custom target type

MyTarget

and a custom

FieldSet

type named

MyFieldSet

. Using

FieldSetsPerTargetRequest

and

FieldSetsPerTarget

to convert a list of

MyTarget

to

MyFieldSet

returns an empty collection, but using

MyFieldSet.is_applicable

and

MyFieldSet.create

works just fine. Is this expected?

Have you registered your FieldSet properly? Pants uses union memberships to find your field sets of a particular kind, so you need

UnionRule(Base, Member)

present in the rule graph for it to work. https://www.pantsbuild.org/2.21/docs/writing-plugins/the-rules-api/union-rules-advanced https://github.com/pantsbuild/pants/blob/71749c04c7cf3cd9c22aea3e99fded57d5f41ebc/src/python/pants/engine/internals/graph.py#L1747-L1759

That's probably the issue. Thank you!