MissingFieldHandlers.js

const missingHandlerByRefConcreteTypeField: MissingFieldHandler = {
  kind: 'linked',
  handle(field, _, argValues) {
    try {
      const argsString =
        field.args && field.args.length
          ? `{${field.args.map(a => `"${a.name}":"${argValues[a.name]}"`).join(',')}}`
          : null;

      const idValue = [field.concreteType, argsString].filter(v => !!v).join(':');
      return base64.encode(idValue);
    } catch (e) {
      // it wasn't be possible to transform the field ref
    }
  },
};