Structural equality helpers (as in io-ts)

[tchak]

One feature I really miss from io-ts is the ability to generate structural equality helpers from schema. Is it something zod might consider in the future?

[JacobWeisenburger]

It might help your question get answered if you were to add some code examples of what you are referring to or maybe a few links that further explain what you mean.

[tchak]

You right. I should have provided an example. I would love for zod schemas to provide an equality function:

const User = z.object({ firstName: z.string(), lastName: z.string() });
const user = { firstName: 'Paul', lastName: 'Chavard' };

User.eq(user, { firstName: 'Paul', lastName: 'Chavard' }); // => true
User.eq(user,  { firstName: 'Jacob', lastName: 'Weisenburger' }); // => false

const users = [{ firstName: 'Jacob', lastName: 'Weisenburger' }, { firstName: 'Paul', lastName: 'Chavard' }];

users.sort(User.ord) // => [{ firstName: 'Paul', lastName: 'Chavard' }, { firstName: 'Jacob', lastName: 'Weisenburger' }]

[scotttrinh]

Oh, that's pretty nice, actually. Nothing planned for that as far as I know, but would be happy to help guide and merge a PR to add something like ZodType.eq and/or ZodType.ord! As far as I know, you'll need to use some other deep-equality checker for now.

[JacobWeisenburger]

You can kinda do this already

const User = z.object({ firstName: z.string(), lastName: z.string() });
const user = { firstName: 'Paul', lastName: 'Chavard' };

User.eq(user, { firstName: 'Paul', lastName: 'Chavard' }); // => true
User.eq(user,  { firstName: 'Jacob', lastName: 'Weisenburger' }); // => false

This would work

const paulChavardSchema = z.object( { firstName: z.literal( 'Paul' ), lastName: z.literal( 'Chavard' ) } )
paulChavardSchema.safeParse( { firstName: 'Paul', lastName: 'Chavard' } ).success // => true
paulChavardSchema.safeParse( { firstName: 'Jacob', lastName: 'Weisenburger' } ).success // => false

---

As far as this part, I'm not sure how sorting is related to structural equality. Please explain.

const users = [{ firstName: 'Jacob', lastName: 'Weisenburger' }, { firstName: 'Paul', lastName: 'Chavard' }];

users.sort(User.ord) // => [{ firstName: 'Paul', lastName: 'Chavard' }, { firstName: 'Jacob', lastName: 'Weisenburger' }]