How to properly use yup validation schema with (React) Final Form?

yup-with-final-form.js

import * as yup from 'yup';
import { setIn } from 'final-form';

const validationSchema = yup.object({
	email: yup.string().email(),
	shipping: yup.object({
		name: yup.string(),
		phone: yup.object({
			code: yup.string().matches(/^\+\d+$/i),
			number: yup.number().max(10),
		}),
		address: yup.string(),
		zip: yup.string(),
	}),
	billing: yup.object({
		name: yup.string(),
		address: yup.string(),
		zip: yup.string(),
	}),
	items: yup.array().of(
		yup.object({
			id: yup.number(),
			price: yup.number(),
			quantity: yup.number(),
		})
	),
});

// To be passed to React Final Form
const validateFormValues = (schema) => async (values) => {
	if (typeof schema === 'function') {
		schema = schema();
	}
	try {
		await schema.validate(values, { abortEarly: false });
	} catch (err) {
		const errors = err.inner.reduce((formError, innerError) => {
			return setIn(formError, innerError.path, innerError.message);
		}, {});

		return errors;
	}
};

const validate = validateFormValues(validationSchema);

const MyForm = () => (
	<Form // from react-final-form
        onSubmit={onSubmit}
		validate={validate}
	/>
);

@manzoorwanijk The module I shared exports both a "simple function" and a hook to use inside components. You can chose to use the one that suits your needs. The hook is just a trivial wrapper that memoizes the function - so both approaches work pretty much the same for the basic scenario. If your components are uncomplicated enough, you're right: you could create the validate function outside the component closure once and re-use it.

That's not always possible, however. A hook may be needed if:

• you need to support i18n on message errors.
• you need/want to defer the creation of your yup schema to component mount.
• your yup schema depends on some data from your component state and needs to be (re-)generated off of it (e.g.: wizards, dynamic forms).

with typescript resolver

import { setIn } from "final-form";
import { AnySchema, ValidationError } from "yup";

export function yupResolver(schema: AnySchema) {
	return async (value: object) => {
		try {
			await schema.validate(value, { abortEarly: false });
		} catch (error) {
			if (error instanceof ValidationError) {
				return error.inner.reduce((errors, error: ValidationError) => {
					const path = error.path ?? "global";
					return setIn(errors, path, error.message);
				}, {});
			}

			throw error;
		}
	};
}

<Form
	onSubmit={(fields) => console.log(fields)}
	validate={yupResolver(SupplierSchema)}...

with typescript resolver

import { setIn } from "final-form";
import { AnySchema, ValidationError } from "yup";

export function yupResolver(schema: AnySchema) {
	return async (value: object) => {
		try {
			await schema.validate(value, { abortEarly: false });
		} catch (error) {
			if (error instanceof ValidationError) {
				return error.inner.reduce((errors, error: ValidationError) => {
					const path = error.path ?? "global";
					return setIn(errors, path, error.message);
				}, {});
			}

			throw error;
		}
	};
}

<Form
	onSubmit={(fields) => console.log(fields)}
	validate={yupResolver(SupplierSchema)}...

thank you