A new way to extend core validators in Medusa v1.x

extend-validator.ts

import { registerOverriddenValidators } from '@medusajs/medusa'
import { type Constructor } from '@medusajs/types'

type DecoratorFunction = MethodDecorator | PropertyDecorator

type ExtensionDefinition = {
  [key: string]: DecoratorFunction | DecoratorFunction[]
}

function extendValidator<Base extends Constructor<any>>(
  BaseValidator: Base,
  extension: ExtensionDefinition,
): void {
  const extensionKeys = Object.keys(extension)

  class ExtendedValidator extends BaseValidator {
    constructor(...args: any[]) {
      super(...args)
      for (let i = 0; i < extensionKeys.length; i++) {
        this[extensionKeys[i]] = undefined
      }
    }
  }

  Object.defineProperty(ExtendedValidator, 'name', { value: BaseValidator.name })

  const proto = ExtendedValidator.prototype

  for (let i = 0; i < extensionKeys.length; i++) {
    const key = extensionKeys[i]
    const decorators = Array.isArray(extension[key]) ? extension[key] : [extension[key]]
    for (let j = 0; j < decorators.length; j++) {
      decorators[j](proto, key, Object.getOwnPropertyDescriptor(proto, key))
    }
  }


  registerOverriddenValidators(ExtendedValidator)
}

export { extendValidator }