Help with circular schemas

[wadjoh]

Hi there! I'm looking into using Valibot for objects that have internal circular relations, but I'm running into issues and hoping I could get some guidance.

For example:
An object will have a User type object, an Auth type object, and a relation object that links them together. The User and Auth objects will hold a reference to the relation object.

const user = {
  firstName: 'joe',
  $relations: {
    // will be assigned farther down
    UserToAuth: undefined
  }
}

const auth = {
  email: 'joe@example.com',
  password: '1234',
  $relations: {
    // will be assigned farther down
    UserToAuth: undefined
  }
}

const userToAuthRelation = {
  from: user,
  to: auth
}

user.$relations.UserToAuth = userToAuthRelation
auth.$relations.UserToAuth = userToAuthRelation

I tried implementing Valibot schemas to validate these objects using lazy:

const UserSchema = v.object({
  firstName: v.string(),
  $relations: v.object({
    UserToCredentials: v.lazy(() => UserToAuthRelationSchema)
  })
})

const AuthSchema = v.object({
  email: v.pipe(v.string(), v.email()),
  password: v.pipe(v.string(), v.minLength(8)),
  $relations: v.object({
    UserToCredentials: v.lazy(() => UserToAuthRelationSchema)
  })
})

type TUserToAuthRelationSchema = {
  from: v.InferOutput<typeof UserSchema>
  to: v.InferOutput<typeof AuthSchema>
}
const UserToAuthRelationSchema: v.GenericSchema<
  TUserToAuthRelationSchema
> = v.pipe(
  v.object({
    from: v.lazy(() => UserSchema),
    to: v.lazy(() => AuthSchema),
  }),
  v.check((input) => !!input && typeof input === 'object')
)

I was able to get the TS types working as expected, but when I call safeParse with this schema and an input object, I get Error: Maximum call stack size exceeded.

I'm wondering if there's something I am doing wrong or if Valibot is not the right solution for this?

I've created a repro example in a few places for convenience:

• Valibot Playground
• Repo
• Stackblitz (linked to repo above)

[fabian-hiller]

I think the main problem is that your data contains a circular reference, which leads to a parse execution that never ends. lazy is intended for recursive schemas like binary trees that end at some point. I think we could technically solve this problem by memorizing what lazy does, but the main question for me is whether this is outside the scope of Valibot. Maybe you should validate the data before it is mapped to be circular.

[wadjoh]

Oh, memoization didn't actually cross my mind. I'll give that a try!

Also, is there a way to stop Valibot from recursing into the objects? I tried using v.check on all those schemas thinking it wouldn't try traversing the objects, but I was still getting the same error.

the main question for me is whether this is outside the scope of Valibot

Yup, that was my thought as well. No problem if it's considered outside of Valibot's scope -- that'd make sense to me.

[fabian-hiller]

No, there is currently no way to stop this. You can try to write your own lazy schema that remembers and breaks circular references.

Here is our code: https://github.com/fabian-hiller/valibot/blob/main/library/src/schemas/lazy/lazy.ts