collectionFetchRelated not working per the guide instructions

[nghamilton]

Following the instructions in the guide, posts :: [Include "comments" Post] <- query @Post |> fetch >>= collectionFetchRelated #comments fails to compile: Couldn't match type ‘Id' "comments"’ with ‘QueryBuilder Comment’

Is the filter on the related models incorrectly using the related model's #id instead of the foreign key field?

This was my workaround:
posts <- mapM (fetchRelated #comments) =<< query @Post |> findManyBy #id postId

[nkpart]

I think the problem is the targetForeignKey line. That requires that the parent model (second argument to collectionFetchRelated) being targeted is a Post' (Id' "comments"), while the result of the first fetch is Post' (QueryBuilder Comment).

FYI This is still a problem today on master