React Hook Form Treating Optional Fields as Required When Using Zod Resolver

[bahag-hamidk]

I’m using React Hook Form with Zod for form validation. My schema has optional fields using .partial(), and when I manually validate the schema with safeParse(), it correctly treats the fields as optional. However, React Hook Form still considers them required and showing validation errors when they are left empty.

Key Observations:

• Zod Works Correctly
• Running safeParse() logs IsSuccess:: true, confirming that Zod allows optional fields.

Our Use Case:

• We have a bank of fields in our schema.
• We pick specific fields based on the form requirements.
• We then make some of these fields optional dynamically.

Codesandbox

Here is the schema code:

const baseSchema = z.object({
  email: z
    .string()
    .nonempty({ message: "Email is required" })
    .email({ message: "Invalid email address" }),
  password: z
    .string()
    .nonempty({ message: "Password is required" })
    .min(6, { message: "Password should be min 6 characters" }),
  first_name: z
    .string()
    .min(1, { message: "First name is required" })
    .max(34, { message: "First name can only have 34 characters " }),
  last_name: z.string().min(1, { message: "Last name is required" }),
  phone: z
    .string()
    .max(16, { message: "Phone number can only be 16 characters long" })
    .regex(/^( )*(0|\+)(\+|0?\d)([0-9]| |[-()])*$/, {
      message: "Phone number in not correct",
    }),
  street: z.string().min(1, { message: "Street is required" }),
  house_number: z.string().min(1, { message: "House number is required" }),
});
const authSchema = baseSchema
  .pick({
    email: true,
    password: true,
    first_name: true,
    last_name: true,
    phone: true,
  })
  .partial({
    // email: true,
    // password: true,
    first_name: true,
    last_name: true,
    phone: true,
  });
const data = authSchema.safeParse({
  email: "test@test.com",
  password: "123456",
});
console.log("IsSuccess::", data.success); // true

const allOptional = authSchema;

type AuthForm = z.infer<typeof allOptional>;

Here is the component code

export default function App() {
  const {
    register,
    handleSubmit,
    formState: { errors },
  } = useForm<AuthForm>({
    resolver: zodResolver(allOptional),
    mode: "onBlur",
  });

  const onSubmit: SubmitHandler<AuthForm> = useCallback(async (value) => {
    console.log(value);
  }, []);

  return (
    <form onSubmit={handleSubmit(onSubmit)} className="">
      <label>
        <span>First name</span>
        <input {...register("first_name")} />
        <span>{errors.first_name?.message}</span>
      </label>
      <label>
        <span>Last name</span>
        <input {...register("last_name")} />
        <span>{errors.last_name?.message}</span>
      </label>
      <label>
        <span>Phone</span>
        <input {...register("phone")} />
        <span>{errors.phone?.message}</span>
      </label>
      <label>
        <span>Email</span>
        <input {...register("email")} />
        <span>{errors.email?.message}</span>
      </label>
      <label>
        <span>Password</span>
        <input {...register("password")} />
        <span>{errors.password?.message}</span>
      </label>
      <button type="submit">Submit</button>
    </form>
  );
}