To skip the extra processing for large arrays, we can add another check for params.bulk before running .map:

const payload = Array.isArray(_data) ? _data : [_data]
const results = (params.bulk ? [] : payload).map((value) => {
  const id = (value as any)[this.id] || this._uId++
  const current = _.extend({}, value, { [this.id]: id })

  return _select((this.store[id] = current), params, this.id)
})

return params.bulk ? [] : Array.isArray(_data) ? results : results[0]

It looks like we also need to address the scenario where we create a single record and also pass params.bulk:

const david = await service.create(
  {
    name: 'David',
    age: 3,
    created: true
  }, 
  { bulk: true }
)

We don't want to return an empty array for the above scenario since that breaks the request-to-response plurality mapping of the service interface. So we probably ought to throw an error:

if (!Array.isArray(_data) && params.bulk) {
  throw new BadRequest()
}

Maybe we can update allowMulti to accept context.id and have a centralized place to throw an error whenever params.bulk === true and

• For create: data is an object
• For patch and remove: context.id is null