failsafeUpdate.ts

import {FormTransportErrors, FormTransportResponse} from 'lib/FormTransport';
import {Model} from './models/Model';

export async function failsafeUpdate<T extends Model<any, any>> (
  instance: T,
  changes: Partial<T>,
  send: (updatedInstance: T) => Promise<FormTransportResponse<T, keyof T>>,
  handleError?: (error: FormTransportErrors<keyof T>) => any
) {
  const updated = new (instance.constructor as Class<T>)().update(instance).update(changes);
  const response = await send(updated);
  if (response.error) {
    if (handleError) {
      handleError(response.error);
    }
  } else {
    instance.update(changes);
  }
  return response;
}