Zod, compare two input fields

[Fred638]

Body

How can one compare the values of two input fields using Zod? Similar to password and confirm password, but the opposite, meaning that the values cannot be the same?

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[Fred638]

Thanks! Exactly what I was looking for. Doesn't fieldB need a custom zod error message when form is submitted?

[Fred638]

Why was the comment removed? What was off-topic? It helped me, but I had a follow up question. Something not according to the guidelines? You people are too fast with "cleaning up".

[tmilost]

Click on the button on the right side, 'Show comment,' to see the comment that was marked as off-topic.

[tmilost]

To compare the values of two input fields using Zod—ensuring the values are not the same (e.g., password and another field should differ)—you can use Zod’s .refine() or .superRefine() for cross-field validation. Here is an example:

import { z } from "zod";

const schema = z.object({
  password: z.string(),
  otherField: z.string(),
}).refine(
  (data) => data.password !== data.otherField,
  {
    message: "The values cannot be the same.",
    path: ["otherField"], // Error will appear on otherField
  }
);

Usage Example:

const result = schema.safeParse({
  password: "mySecret",
  otherField: "mySecret",
});

console.log(result.success); // false
console.log(result.error?.issues); // Shows the custom error

Explanation:

• .refine() takes a function that receives all the fields, so you can compare password and otherField.
• If the function returns false, Zod will throw the provided message.

Tip:

• Use .superRefine() if you need to show an error on both fields or want more advanced logic.