Ecto - Why doesn't `Jason.encode` work for interpolating in `jsonb` queries?

Okay, figured it out:

Instead of using Jason.encode, use type/2 with :map:

intern = %{"Employment Type" => "Intern"}
insert(:job, custom_fields: intern)

query =
 from j in Job,
 as: :job,
 where: fragment("custom_fields @> ?::jsonb", type(^intern, :map)),
 select: j.id

Thanks!