An idea for tracking fields in GraphQL

performance_tracking_middleware.rb

# An untested idea to add performance tracking to graphql queries 
# 
# TODO: what's the best way of tracking time in the app? `Time.now.to_f`?
#
# When you define your schema, you could add this middleware: 
#
# ```
# MySchema.middleware << PerformanceTrackingMiddleware.new 
# ```
# 
# More about middlewares for the GraphQL gem: https://github.com/rmosolgo/graphql-ruby/blob/master/guides/defining_your_schema.md#middleware
#
class PerformanceTrackingMiddleware 
  def call(parent_type, parent_object, field_definition, field_args, query_context, next_middleware)
    field_name = "#{parent_type.name}.#{field_definition.name}"
    field_args_string = field_args.to_h.to_json 
    
    # Get the time _before_ resolving 
    before_time = Time.now
    
    # Resolve the field as normal: 
    resolved_object = next_middleware.call 
    
    # Get the time _after_ resolving 
    after_time = Time.now 
    
    # Push your info to whatever tracking service 
    TrackingService.track_event(
      event_name: field_name, 
      event_metadata: field_args_string, 
      duration: after_time - before_time
    )
    
    # Return the resolved object:
    resolved_object
  end
end