Best practices

Recursive mappers

Sometimes, mapper has to call itself (category containing child categories). Such mappers should import itself from IoC and use this imported value to call itself recursively.

Example

// mappers/ToCategory.ts

import ToCategory from '#ioc/mappers/ToCategory'

export default (data: any) => ({
  id: data.id as string,
  name: data.name as string,
  children: data.children.map(ToCategory),
})

WARNING

Types of recursive mappers can't be inferred by TypeScript. Either, the recursive fields have to be typed as any or explicit interface has to be used.

Typing extensions

Extensions can be typed easily with two generic types.

Example

// composables/useProduct.ext.ts

interface Extension<Ext = Record<string, never>> {
  <T extends (...arg: any) => any>(useProduct: T): (...arg: any) => ReturnType<T> & Ext
}

interface Message {
  message: string
}

const useProduct: Extension<Message> =
  (useProduct) =>
  (...args) => {
    const product = useProduct(...args)

    product.message = 'Hello, World!'

    return product
  }