# KeyExists - `KeyExists(string|int $key)` Validates if the given key exists in an array. ```php v::keyExists('name')->assert(['name' => 'The Respect Panda']); // Validation passes successfully v::keyExists('name')->assert(['email' => 'therespectpanda@gmail.com']); // → `.name` must be present v::keyExists(0)->assert(['a', 'b', 'c']); // Validation passes successfully v::keyExists(4)->assert(['a', 'b', 'c']); // → `.4` must be present v::keyExists('username')->assert(new ArrayObject(['username' => 'therespectpanda'])); // Validation passes successfully v::keyExists(5)->assert(new ArrayObject(['a', 'b', 'c'])); // → `.5` must be present ``` ## Notes - To validate an array against a given validator if the key exists, use [KeyOptional](KeyOptional.md) instead. - To validate an array against a given validator requiring the key to exist, use [Key](Key.md) instead. ## Templates ### `KeyExists::TEMPLATE_STANDARD` | Mode | Template | | ---------: | :------------------------------ | | `default` | {{subject}} must be present | | `inverted` | {{subject}} must not be present | ## Template placeholders | Placeholder | Description | | ----------- | ---------------------------------------------------------------- | | `subject` | The validated input or the custom validator name (if specified). | ## Caveats `KeyExists` defines the given `$key` as the path, and because it is a standalone validator without children, it's not possible to display a fully custom name with it. When no custom name is set, the path is displayed as `{{name}}`. When a custom name is set, the validation engine prepends the path to the custom name: ```php v::keyExists('foo')->assert([]); // → `.foo` must be present v::named('Custom name', v::keyExists('foo'))->assert([]); // → `.foo` (<- Custom name) must be present ``` If you want to display only a custom name while checking if a key exists, use [Key](Key.md) with [AlwaysValid](AlwaysValid.md): ```php v::key('foo', v::named('Custom name', v::alwaysValid()))->assert([]); // → Custom name must be present ``` ## Categorization - Arrays - Structures ## Changelog | Version | Description | | ------: | :------------------------- | | 3.0.0 | Created from [Key](Key.md) | ## See Also - [AlwaysValid](AlwaysValid.md) - [ArrayType](ArrayType.md) - [ArrayVal](ArrayVal.md) - [Each](Each.md) - [Key](Key.md) - [KeyOptional](KeyOptional.md) - [Property](Property.md) - [PropertyExists](PropertyExists.md) - [PropertyOptional](PropertyOptional.md)