Theo's Typesafe Cult•2y ago

Proper way to declare with Zod

hi guys, Noob question: Is it better to: A) create types and then check them with zod? or B) better to create Zod objects and then infer types from them? I think i would prefer to do A since it appears cleaner to me, but i also dont see them doing it like this in the docs, so i wonder why?

//A - Types first
type AThing = { thing: string };
const A: AThing = { thing: "A" };
const ASchema = z.infer(AThing);
const AisValid = !!ASchema.parse(A);

//B - Zod first
const BSchema = z.object({ thing: z.string() });
type BThing = z.infer<typeof B>
const B: BThing = { thing: "B" };
const BisValid = !!BSchema.parse(B)

//A - Types first
type AThing = { thing: string };
const A: AThing = { thing: "A" };
const ASchema = z.infer(AThing);
const AisValid = !!ASchema.parse(A);

//B - Zod first
const BSchema = z.object({ thing: z.string() });
type BThing = z.infer<typeof B>
const B: BThing = { thing: "B" };
const BisValid = !!BSchema.parse(B)

2 Replies

Vincent Udén•2y ago

Zod schemas can include a lot more information than you'd be able to provide with just one example of an object.

const schema = z.object({
  thing: z.string().email().min(5),
  otherThing: z.string().nullish(),
})

const schema = z.object({
  thing: z.string().email().min(5),
  otherThing: z.string().nullish(),
})

For example this declares that thing must match an email regex and be at least 5 chars long. While otherThing must be a string | null | undefined

fotoflo•2y ago

Thank you! Agreed - the draw back is harder to incrementally adopt but this will be better

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Proper way to declare with Zod