location.ts

import { LocationBaseMixin } from './generated/location_base.ts';

type Constructor<T = {}> = new (...args: any[]) => T;

interface ILocation {
  isAddressInCalifornia: () => boolean;
}

export function LocationMixin<T extends Constructor>(BaseClass: T) {
  return class LocationMixin extends LocationBaseMixin(BaseClass) implements ILocation {
    isAddressInCalifornia() {
      return this.state === 'CA';
    }
  }
}

location_base.ts

import { Data, Viewer, Ent } from '@snowtop/ent';
import { Country, convertNullableCountry } from '../types';

type Constructor<T = {}> = new (...args: any[]) => T;

export function isLocation(ent: unknown): ent is ILocation {
  const o = ent as ILocation;
  return (o.isLocation && o.isLocation()) ?? false;
}

interface ILocation extends Ent {
  isLocation(): boolean;
  address: string | null;
  address2: string | null;
  city: string | null;
  state: string | null;
  postalCode: string | null;
  country: Country | null;
}

function extractFromArgs<TViewer extends Viewer, TData extends Data>(
  args: any[],
): { viewer: TViewer; data: TData } {
  if (args.length !== 2) {
    throw new Error('args should be length 2');
  }
  return {
    viewer: args[0],
    data: args[1],
  };
}

export function LocationBaseMixin<T extends Constructor>(BaseClass: T) {
  return class LocationBaseMixin extends BaseClass {
    readonly address: string | null;
    readonly address2: string | null;
    readonly city: string | null;
    readonly state: string | null;
    readonly postalCode: string | null;
    readonly country: Country | null;
    constructor(...args: any[]) {
      super(...args);
      const { data } = extractFromArgs(args);
      this.address = data.address;
      this.address2 = data.address_2;
      this.city = data.city;
      this.state = data.state;
      this.postalCode = data.postal_code;
      this.country = convertNullableCountry(data.country);
    }

    isLocation() {
      return true;
    }
  };
}

The base class is generated while the second class is only generated the first time. It’s the same logic as normal ents. This lets you add custom methods to the pattern that won’t be overwritten if re-generated.

got it