Using custom with a predefined schema?

[subvertallchris]

Hello! I'm exploring a migration from Zod to Valibot and stuck on what I assume is a simple issue.

In Zod, I can take a schema, fooSchema, and use refine later on to add additional logic, perhaps in a form that has some unique quality that shouldn't be shared in the base schema definition. Valibot's equivalent seems to be custom, but I can only use this in a pipeline when defining the original schema. I'm looking for something like this:

const fooSchema = v.object({ foo: v.string([v.toTrimmed(), v.email()]) });

// This does not work, what is the correct equivalent?
const extendedFoo = v.object(fooSchema, v.custom(({ foo }) => {
  // some additional logic here
});

Thank you for your help!

[fabian-hiller]

This is already possible, but I am aware that it is a bit cumbersome. That's why we're currently changing that part of the API in #502.

Check the code out in our playground

import * as v from 'valibot';

const FooSchema = v.object({ foo: v.string([v.toTrimmed(), v.email()]) });

const ExtendedFoo = v.object(FooSchema.entries, [
  v.custom(({ foo }) => foo.includes('@gmail'), 'Error: Not a Gmail!')
]);

[fabian-hiller]

In the future, you can write the following:

import * as v from 'valibot';

const FooSchema = v.object({ foo: v.pipe(v.string(), v.toTrimmed(), v.email()) });

const ExtendedFoo = v.pipe(
  FooSchema,
  v.check(({ foo }) => foo.includes('@gmail'), 'Error: Not a Gmail!')
);

[subvertallchris]

This is great! The current syntax isn’t terrible but the new syntax is quite exciting and will be a very significant improvement. Thank you so much for the quick reply and all your work!