required_if

Makes the field required when other fields have the given values.

Error code: REQUIRED

Live example · edit rules or inputOpen in playground

rules

{
    type: ['required', { one_of: ['person', 'company', 'ngo'] }],
    vat: { required_if: { type: ['company', 'ngo'] } }
}

{
    type: ['required', { one_of: ['person', 'company', 'ngo'] }],
    vat: { required_if: { type: ['company', 'ngo'] } }
}

input

{
    type: 'company'
}

{
    type: 'company'
}

Invaliderrors

{
  "vat": "REQUIRED"
}

{
    type:    ['required', { one_of: ['person', 'company', 'ngo'] }],
    company: { required_if: { type: 'company' } },
    vat:     { required_if: { type: ['company', 'ngo'] } },
    zip:     { required_if: { 'address/country': 'UA' } }
}

The argument is an object with at least one entry. Each key is a reference to another field, each value is a primitive value other than null, or a non-empty list of such values.

An entry matches when the referenced value is a primitive value, is not empty, and equals the given value or one of the listed values. Values are compared as strings.
When all entries match, the field is required: an empty value gives REQUIRED. Otherwise the rule passes.
The output is the value unchanged.

The referenced value is the input, before the rules of that field. So { subscribe: true } matches true and "true", but not "1" or "on" that a form sends for a checkbox, and { type: 'company' } does not match "Company" even if type has to_lc. For checkboxes use when with boolean in the condition:

{ email: ['email', { when: ['subscribe', ['boolean', { eq: true }], 'required'] }] }

'' as a value, alone or in a list, is a schema error, because an empty referenced value never matches. So is an empty list []: it never matches either.

required_if ​

required_if