Error codes

LIVR returns error codes, not messages. Codes are stable across implementations, so you can map them to messages in any language of your interface.

Shape of errors

Errors have the same shape as the data. Every invalid field gets its error code, nested objects get nested errors, and lists get a list of errors with null for valid elements:

{
    name: 'REQUIRED',
    address: { zip: 'NOT_POSITIVE_INTEGER' },
    tags: [null, 'TOO_LONG']
}

An alias can replace the errors of its rules with a single custom code, see Rules aliasing.

All error codes

Code	Meaning	Returned by
REQUIRED	The value is missing, null or an empty string	required
CANNOT_BE_EMPTY	The value is an empty string, or the list is empty	not_empty, not_empty_list
FORMAT_ERROR	The value has a wrong type: an object or a list where a primitive value is expected, or vice versa	Almost every rule, see below
NOT_ALLOWED_VALUE	The value is not one of the allowed values	eq, one_of
TOO_LONG	The string is too long	max_length, length_between, length_equal
TOO_SHORT	The string is too short	min_length, length_between, length_equal
WRONG_FORMAT	The string does not match the regular expression	like
NOT_INTEGER	The value is not an integer	integer
NOT_POSITIVE_INTEGER	The value is not an integer greater than zero	positive_integer
NOT_DECIMAL	The value is not a number	decimal
NOT_POSITIVE_DECIMAL	The value is not a number greater than zero	positive_decimal
NOT_NUMBER	The value is not a number	max_number, min_number, number_between
TOO_HIGH	The number is too high	max_number, number_between
TOO_LOW	The number is too low	min_number, number_between
WRONG_EMAIL	The value is not an email	email
WRONG_URL	The value is not an http or https URL	url
WRONG_DATE	The value is not an ISO 8601 date	iso_date
FIELDS_NOT_EQUAL	The value differs from the value of another field	equal_to_field

FORMAT_ERROR

FORMAT_ERROR means that the value has a type the rule cannot handle:

• string, numeric and special rules return it for objects and lists;
• any_object and nested_object return it for anything that is not an object;
• not_empty_list, list_of, list_of_objects and list_of_different_objects return it for anything that is not a list (or a list of objects);
• variable_object and list_of_different_objects also return it when the selector field is missing or has an unknown value.

Modifiers never return errors. All rules except required, not_empty and not_empty_list skip empty values (missing, null or ""), so for them an empty value never causes FORMAT_ERROR.