No .partial(), .deepPartial(), .merge() and others after using .refine() on ZodObject

The refine method on a ZodObject instance returns a ZodEffects instance which lacks any of the object methods. It broke some code after migrating to v3. I don’t know the reasons behind this change, I guess it’s to support chaining multiple refine and transform calls, but maybe there’s a way to keep the original methods. It should also benefit another schema types’ methods.

[scotttrinh]

I’ve already considered and tried the solution you suggested, but the derived userDataSchema (and others that are not included in the sample code) is used in a lot of places (within other intersections for ex.) and is very prone to error having to remember (or other devs having to guess) to add the refinement every time.

Yeah, I think the only way to avoid that is to use naming conventions and comments like:

// Note: this schema is unchecked for business logic refinement
export const unsafeCredentialDataSchema = z.object({
  // ...
});

export const credentialDataSchema = unsafeCredentialDataSchema.refine(usZipcodeRefinement);

[scotttrinh]

@kevlugli

Your example demonstrates the difficulty of a general solution. refine assumes that the input type is not-partial, so you would get runtime errors when trying to access undefined fields in your refinement function. Take this example given your schemas:

credentialEditionDataSchema.parse({
  firstName: "Scott",
  lastName: "Trinh",
  zipCode: "100001",
  birthday: new Date(2030, 0, 1),
});

In your particular refinement’s case, you’re testing data.countryId === "US" so you don’t fall into a runtime error, but imagine you wanted to normalize the string first like data.countryId.toUppercase() === "US", the compiler would not be able to tell you that it’s invalid since the type of data is not partial.

I know it’s annoying to have to respecify refinements, but I think if you end up transforming a type that you also need to refine, you’ll want to maybe share refinements that are defensive and applicable to all of the possible input values.

const usZipcodeRefinement = (data: { countryId?: string; zipCode?: string | null }) => {
  const isUs = data.countryId === 'US';
  const isEmpty = data.zipCode === undefined || data.zipCode === null;

  return !((isUs && isEmpty) || (!isUs && !isEmpty));
};

Then you can export an unrefined version that you can call .partial().refine(usZipcodeRefinement) on and a refined version that you can use on it’s own.