unstable_coerceFormValue

The coerceFormValue function is also available as part of Conform's future export. Check it out if you want to use it with other future APIs.

A helper that enhances the schema with extra preprocessing steps to strip empty values and coerce form values to the expected type. To customize the coercion behavior, use configureCoercion from the future export.

const enhancedSchema = coerceFormValue(schema);

The following rules are applied by default:

1. If the value is an empty string / file, pass undefined to the schema
2. If the schema is z.number(), trim the value and cast it with the Number constructor
3. If the schema is z.boolean(), treat the value as true if it equals on (browser default value of a checkbox / radio button)
4. If the schema is z.date(), cast the value with the Date constructor
5. If the schema is z.bigint(), trim the value and cast it with the BigInt constructor

#Parameters

schema

The zod schema to be enhanced.

#Example

import { useForm } from '@conform-to/react';
import {
  parseWithZod,
  unstable_coerceFormValue as coerceFormValue,
} from '@conform-to/zod';
// If you are using Zod v4, update the imports:
// import { parseWithZod, unstable_coerceFormValue as coerceFormValue } from '@conform-to/zod/v4';
import { z } from 'zod';

const schema = coerceFormValue(
  z.object({
    ref: z.string(),
    date: z.date(),
    amount: z.number(),
    confirm: z.boolean(),
  }),
);

function Example() {
  const [form, fields] = useForm({
    onValidate({ formData }) {
      return parseWithZod(formData, {
        schema,
        disableAutoCoercion: true,
      });
    },
  });

  // ...
}

#Tips

Default values

coerceFormValue will always strip empty values to undefined. If you need a default value, use .transform() to define a fallback value that will be returned instead.

const schema = z.object({
  foo: z.string().optional(), // string | undefined
  bar: z
    .string()
    .optional()
    .transform((value) => value ?? ''), // string
  baz: z
    .string()
    .optional()
    .transform((value) => value ?? null), // string | null
});