demo_schema.rb

class DemoSchema < GraphQL::Schema
  mutation(Types::MutationType)
  query(Types::QueryType)

  # Union and Interface Resolution
  def self.resolve_type(abstract_type, obj, ctx)
    case obj
    when Product
      Types::ProductType
    else
      raise("Unexpected object: #{obj}")
    end
  end

  # Relay-style Object Identification:

  # Return a string UUID for `object`
  def self.id_from_object(object, type_definition, query_ctx)
    # Here's a simple implementation which:
    # - joins the type name & object.id
    # - encodes it with base64:
    GraphQL::Schema::UniqueWithinType.encode(type_definition.name, object.id)
  end

  # Given a string UUID, find the object
  def self.object_from_id(id, query_ctx)
    # Decode the UUIDs generated above:
    type_name, item_id = GraphQL::Schema::UniqueWithinType.decode(id)

    # Then, based on `type_name` and `id`
    # find an object in your application
    Object.const_get(type_name).find(item_id)
  end
end