Simple example of a field result being returned as a GraphQL type

schema.ex

mutation do
  field :create_foo, :create_foo_result do
    resolve fn _, _ ->
      # Return an :ok w/ a :create_foo_result
      # containing a `foo` and/or `errors`
    end
  end
end

@desc "The result of creating a Foo"
object :create_foo_result do
  field :foo, :foo
  field :errors, list_of(:input_error)
end

@desc "An error encountered trying to persist input"
object :input_error do
  field :key, non_null(:string)
  field :message, non_null(:string)
end