How to query by missing relationship in GraphQL?

Question

Is it possible in GraphQL to query for records missing a certain relationship?

Eg

Type Foo
  - id
Type Bar
  - id
  - foo_id

How can I search for Foo which don't have any Bar associated?

Answer 1

I think I found the answer.

query FooMissingBar {
  foo(where: { _not: { bar: {} } }) {
    id
  }
}