Yup validation check if not empty - yup

Question

const validationSchema = Yup.object().shape({
newPassword: Yup.string().min(8, 'Password must be at least 8 characters');
});
I want to validation check only if newPassword field is not empty.
How could I do?

Answer 1

There are different approach on solving this problem.
Using test
const validationSchema = Yup.object().shape({
newPassword: Yup.string().test(
'empty-check',
'Password must be at least 8 characters',
password => password.length == 0
});
Using when
const validationSchema = Yup.object().shape({
newPassword: Yup.string().when('newPassword',{
is:(password) => password.length > 0
then: Yup.string().min(8, 'Password must be at least 8 characters');
});

Answer 2

Alternative using test:
const validationSchema = Yup.object().shape({
newPassword: Yup.string().test(
'empty-or-8-characters-check',
'Password must be at least 8 characters',
password => !password || password.length >= 8,
),
});

Answer 3

Alternative using trim()
const validationSchema = Yup.object().shape({
newPassword: Yup.string().trim().required("Password must be at least 8 characters"),
});

Answer 4

There is a way of using .when() and not generating a cyclic dependency like the accepted answer, .shape() accepts an exhaustive list of dependencies as last argument, that resolves the cyclic conflict, the secret is using the same key twice https://github.com/jquense/yup/issues/176#issuecomment-369925782
const validationSchema = Yup.object().shape({
newPassword: Yup.string().test(
'empty-or-8-characters-check',
'Password must be at least 8 characters',
password => !password || password.length >= 8,
),
}, [["newPassword","newPassword"]]);

Answer 5

The way I solved this for myself was to first add .nullable() and then .transform() empty string into a null.
const validationSchema = Yup.object().shape({
newPassword: Yup
.string()
.nullable()
.transform((v, o) => (o === '' ? null : v))
.min(8, 'Password must be at least 8 characters')
});

Answer 6

The simplest way is:
const validationSchema = Yup.object().shape({
newPassword: Yup
.string()
.matches(/^\w{8}/, "Password must be at least 8 characters")
});

Answer 7

Alternative that won't allow 8 empty characters.
const notEmpty = Yup.string()
.ensure() // Transforms undefined and null values to an empty string.
.test('Only Empty?', 'Cannot be only empty characters', (value) => {
const isValid = value.split(' ').join('').length !== 0;
return isValid;
});
const validationSchema = Yup.object({
newPassword: notEmpty.min(8, 'Password must be at least 8 characters');
});

Answer 8

I used the Yup function nullable() so it is only validated with the next functions if it not null:
kmBegin: Yup.number().nullable().positive().integer(),
parcelTotal: Yup.number().positive().integer(),
timeBegin: Yup.date(),
timeEnd: Yup.date().nullable(),