Undef
February 3, 2026 · View on GitHub
Undef()
Validates if the given input is undefined. By undefined we consider null or an empty string ('').
We recommend you to check Comparing empty values for more details.
v::undef()->assert('');
// Validation passes successfully
v::undef()->assert(null);
// Validation passes successfully
Other values similar to undefined values are considered defined:
v::undef()->assert([]);
// → `[]` must be undefined
v::undef()->assert(' ');
// → " " must be undefined
v::undef()->assert(0);
// → 0 must be undefined
v::undef()->assert('0');
// → "0" must be undefined
v::undef()->assert('0.0');
// → "0.0" must be undefined
v::undef()->assert(false);
// → `false` must be undefined
v::undef()->assert(['']);
// → `[""]` must be undefined
v::undef()->assert([' ']);
// → `[" "]` must be undefined
v::undef()->assert([0]);
// → `[0]` must be undefined
v::undef()->assert(['0']);
// → `["0"]` must be undefined
v::undef()->assert([false]);
// → `[false]` must be undefined
v::undef()->assert([[''], [0]]);
// → `[[""], [0]]` must be undefined
v::undef()->assert(new stdClass());
// → `stdClass {}` must be undefined
Templates
Undef::TEMPLATE_STANDARD
| Mode | Template |
|---|---|
default | {{subject}} must be undefined |
inverted | {{subject}} must be defined |
Template placeholders
| Placeholder | Description |
|---|---|
subject | The validated input or the custom validator name (if specified). |
Categorization
- Miscellaneous
Changelog
| Version | Description |
|---|---|
| 3.0.0 | Renamed to Undef and changed the behavior |
| 1.0.0 | Created as NotOptional |