Retrieving the queried fields from a GraphQL operation request (when using `graphql-ruby` gem)

lib__graphql__utils.rb

module Graphql
  class Utils
    CONTEXT_CLASS = GraphQL::Query::Context
    FIELD_CLASS = GraphQL::Language::Nodes::Field
    FRAGMENT_CLASS = GraphQL::Language::Nodes::FragmentSpread

    # Given a GraphQL context (literally, the +context+ method from inside any GraphQL field
    # method), this method will return all the fields requested in the operation request.
    # So, considering the following query example:
    #
    #   query pipelinesWithStagesForSelect {
    #     pipelines {
    #       id
    #       name
    #       stages {
    #         id
    #         name
    #         order
    #         color
    #       }
    #     }
    #   }
    #
    # This method will return the following array:
    #
    #   [
    #     "pipelines.id",
    #     "pipelines.name",
    #     "pipelines.stages.id",
    #     "pipelines.stages.name",
    #     "pipelines.stages.order",
    #     "pipelines.stages.color"
    #   ]
    #
    def self.query_fields(object, fields_path = [], context = object)
      collection_from(object, context).flat_map do |field|

        next unless field?(field) || fragment?(field)
        next if field.name == '__typename'

        children = collection_from(field, context).presence
        field_name = field.name.underscore
        next_path = fields_path + (fragment?(field) ? [] : [field_name])

        children && query_fields(field, next_path, context) || next_path.join('.')
      end.compact
    end

    class << self
      private

      def context?(object) = object.is_a?(CONTEXT_CLASS)
      def field?(object) = object.is_a?(FIELD_CLASS)
      def fragment?(object) = object.is_a?(FRAGMENT_CLASS)

      def collection_from(object, context)
        return object.children if field?(object)
        return context.query.fragments[object.name].children if fragment?(object)

        object.query.selected_operation.children if context?(object)
      end
    end
  end
end

pipeline_query_type.rb

module Types
  module Queries
    module PipelineQueryType
      include Base

      def pipelines
        fields = Graphql::Utils.query_fields(context)
        Pipelines::List.call(firm: current_firm, queried_fields: fields).pipelines
      end
    end
  end
end