Mongoose post init hook in typescript

Nutrient.ts

// @ts-ignore
nutrientSchema.post('init', async function(this: NutrientInstance) {
  // noinspection JSDeprecatedSymbols
  if (!this.displayUnitCode && this.displayUnitId) {
    const unit = await NutrientUnitModel.findById(this.displayUnitId);
    if (unit) {
      this.displayUnitCode = unit.code;
      await this.save();
    }
  }
});