Filtering across relationships

[lastmjs]

See here: aerogear/graphback#1343

[danielrearden]

What would the API for filtering by relationships look like? It'd be easy enough to nest the Inputs:

input NoteFilter {
  id: IDInput
  title: StringInput
  ...
  and: [NoteFilter]
  or: [NoteFilter]
  not: NoteFilter
  comments: CommentFilter
}

The issue is that for one-to-many and many-to-many relationships, there's actually two different filters you might want to apply
-- 1) at least one of the related records satisfies the filter; or

2. all of the related records satisfy the filter.

Prisma solves this by providing explicit operators to this effect.

Hasura takes a different approach and effectively puts it on the consumer to craft the appropriate query using the existing operators (see here).

I'm partial to the latter, if only because it simplifies implementation, but I can see how the former can make for a clearer API. If the spec adopts the latter approach, we should make sure to document it thoroughly.