Zod•3mo ago

Steve - I was wondering if there is a certain w...

I was wondering if there is a certain way to further optimize the .refine. And if possible, also improve the typing of it. Basically also wondering I would be able to type TipTapTextDto['marks'] In a way that I define it to be an array of TipTapMarkDto but also it to have at least one IdentifierMarkDto, no matter the order in which the TipTapMarkDto present themselves.

import { z } from 'zod'

const SimpleMarkDto = <T extends string>(typeName: T) =>
  z.object({
    type: z.literal(typeName),
  })

const IdentifierMarkDto = z
  .object({
    type: z.literal('identifier'),
    attrs: z.object({
      identifier: z.string(),
    }),
  })
  .strict()

const BoldMarkDto = SimpleMarkDto('bold')
const ItalicMarkDto = SimpleMarkDto('italic')
const StrikeMarkDto = SimpleMarkDto('strike')
const CodeMarkDto = SimpleMarkDto('code')
const SubscriptMarkDto = SimpleMarkDto('subscript')
const SuperscriptMarkDto = SimpleMarkDto('superscript')
const UnderlineMarkDto = SimpleMarkDto('underline')

export const TipTapMarkDto = z.union([
  SuperscriptMarkDto,
  SubscriptMarkDto,
  CodeMarkDto,
  StrikeMarkDto,
  BoldMarkDto,
  ItalicMarkDto,
  UnderlineMarkDto,
  IdentifierMarkDto,
])
export type TipTapMarkDto = z.infer<typeof TipTapMarkDto>

export const TipTapTextDto = z
  .object({
    type: z.literal('text'),
    text: z.string(),
    marks: z.array(TipTapMarkDto).default([]),
  })
  .strict()
  .refine((dto) => dto.marks.some((mark) => mark.type === 'identifier'), {
    message: 'Should have an identifier',
  })
export type TipTapTextDto = z.infer<typeof TipTapTextDto>

import { z } from 'zod'

const SimpleMarkDto = <T extends string>(typeName: T) =>
  z.object({
    type: z.literal(typeName),
  })

const IdentifierMarkDto = z
  .object({
    type: z.literal('identifier'),
    attrs: z.object({
      identifier: z.string(),
    }),
  })
  .strict()

const BoldMarkDto = SimpleMarkDto('bold')
const ItalicMarkDto = SimpleMarkDto('italic')
const StrikeMarkDto = SimpleMarkDto('strike')
const CodeMarkDto = SimpleMarkDto('code')
const SubscriptMarkDto = SimpleMarkDto('subscript')
const SuperscriptMarkDto = SimpleMarkDto('superscript')
const UnderlineMarkDto = SimpleMarkDto('underline')

export const TipTapMarkDto = z.union([
  SuperscriptMarkDto,
  SubscriptMarkDto,
  CodeMarkDto,
  StrikeMarkDto,
  BoldMarkDto,
  ItalicMarkDto,
  UnderlineMarkDto,
  IdentifierMarkDto,
])
export type TipTapMarkDto = z.infer<typeof TipTapMarkDto>

export const TipTapTextDto = z
  .object({
    type: z.literal('text'),
    text: z.string(),
    marks: z.array(TipTapMarkDto).default([]),
  })
  .strict()
  .refine((dto) => dto.marks.some((mark) => mark.type === 'identifier'), {
    message: 'Should have an identifier',
  })
export type TipTapTextDto = z.infer<typeof TipTapTextDto>

Solution:

You could use something like a brand to indicate to the consumer that it has been verified to contain a certain element, but the type system still wouldn't know how to encode that information, so you'd still have to code defensively

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5 Replies

SteveOP•3mo ago

The first optimization of this is ofcourse rewriting it to this:

export const TipTapTextDto = z
  .object({
    type: z.literal('text'),
    text: z.string(),
    marks: z
      .array(TipTapMarkDto)
      .default([])
      .refine((marks) => marks.some((mark) => mark.type === 'identifier'), {
        message: 'Should have an identifier',
      }),
  })
  .strict()

export type TipTapTextDto = z.infer<typeof TipTapTextDto>

export const TipTapTextDto = z
  .object({
    type: z.literal('text'),
    text: z.string(),
    marks: z
      .array(TipTapMarkDto)
      .default([])
      .refine((marks) => marks.some((mark) => mark.type === 'identifier'), {
        message: 'Should have an identifier',
      }),
  })
  .strict()

export type TipTapTextDto = z.infer<typeof TipTapTextDto>

Scott Trinh•3mo ago

In a way that I define it to be an array of TipTapMarkDto but also it to have at least one IdentifierMarkDto, no matter the order in which the TipTapMarkDto present themselves.

No 😅 . If you don't know exactly where it is (like first, or last, or third, etc) you cannot encode that invariant in the type itself. That's basically a feature of a dependent type system and TypeScript doesn't have a real dependent type system.

Solution

Scott Trinh•3mo ago

SteveOP•3mo ago

😦 too bad

Scott Trinh•3mo ago

I guess one work around here is to use a combination of a runtime check with a branded type, and then write a function to extract the known value from the array that makes a type assertion. Or you can skip the branding and make a falliable function that will return the value if it exists or throw.

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Steve - I was wondering if there is a certain w...