... field by calling .for with the grouping arguments to get a loader instance, then call .load on that instance with the key to load. Although this library doesn't have a dependency on active record, the examples directory has record and association loaders for active record which handles edge cases like type-casting ids. GraphQL::Batch::Loader#load returns a Promise using the promise.rb gem to provide a promise-based API, so you can transform the query results using .then.