class GraphQL::Schema::Directive::Transform

}
username @transform(by: “upcase”)
viewer {
@example Transforming strings
end
directive(GraphQL::Schema::Directive::Transform)
class MySchema < GraphQL::Schema
@example Installing the directive
it’s applied by calling a method with that name.
and if the named transform is whitelisted and applies to the return value,
This directive takes the return value of the tagged part of the query,
An example directive to show how you might interact with the runtime.

def self.resolve(object, arguments, context)

Implement the Directive API 
def self.resolve(object, arguments, context)
  path = context.namespace(:interpreter)[:current_path]
  return_value = yield
  transform_name = arguments[:by]
  if TRANSFORMS.include?(transform_name) && return_value.respond_to?(transform_name)
    return_value = return_value.public_send(transform_name)
    response = context.namespace(:interpreter)[:runtime].final_result
    *keys, last = path
    keys.each do |key|
      if response && (response = response[key])
        next
      else
        break
      end
    end
    if response
      response[last] = return_value
    end
    nil
  end
end