CakePHP - Validation

Often while making websites we need to validate certain things before processing data further. CakePHP provides validation package to build validators that can validate data with ease.

Validation Methods

CakePHP provides various validation methods in the Validation Class. Some of the most popular of them are listed below.

Syntax	Add (string $field, array|string $name, array|Cake\Validation\ValidationRule $rule [] )
Parameters	The name of the field from which the rule will be added. The alias for a single rule or multiple rules array. The rule to add
Returns	$this
Description	Adds a new rule to a field's rule set. If second argument is an array, then rules list for the field will be replaced with second argument and third argument will be ignored.

Syntax	allowEmpty (string $field, boolean|string|callable $when true, string|null $message null)
Parameters	The name of the field. Indicates when the field is allowed to be empty. Valid values are true (always), 'create', 'update'. If a callable is passed, then the field will be left empty only when the callback returns true. The message to show if the field is not.
Returns	$this
Description	Allows a field to be empty.

Syntax	alphanumeric (string $field, string|null $message null, string|callable|null $when null)
Parameters	The field you want to apply the rule to. The error message when the rule fails. Either 'create' or 'update' or a callable that returns true when the validation rule should be applied.
Returns	$this
Description	Add an alphanumeric rule to a field.

Syntax	creditCard (string $field, string $type 'all', string|null $message null, string|callable|null $when null)
Parameters	The field you want to apply the rule to. The type of cards you want to allow. Defaults to 'all'. You can also supply an array of accepted card types, for example, ['mastercard', 'visa', 'amex']. The error message when the rule fails. Either 'create' or 'update' or a callable that returns true when the validation rule should be applied.
Returns	$this
Description	Add a credit card rule to a field.

Syntax	Email (string $field, boolean $checkMX false, string|null $message null, string|callable|null $when null)
Parameters	The field you want to apply the rule to. Whether or not to check the MX records. The error message when the rule fails. Either 'create' or 'update' or a callable that returns true when the validation rule should be applied.
Returns	$this
Description	Add an email validation rule to a field.

Syntax	maxLength (string $field, integer $max, string|null $message null, string|callable|null $when null)
Parameters	The field you want to apply the rule to. The maximum length allowed. The error message when the rule fails. Either 'create' or 'update' or a callable that returns true when the validation rule should be applied.
Returns	$this
Description	Add a string length validation rule to a field.

Syntax	minLength (string $field, integer $min, string|null $message null, string|callable|null $when null)
Parameters	The field you want to apply the rule to. The maximum length allowed. The error message when the rule fails. Either 'create' or 'update' or a callable that returns true when the validation rule should be applied.
Returns	$this
Description	Add a string length validation rule to a field.

Syntax	notBlank (string $field, string|null $message null, string|callable|null $when null)
Parameters	The field you want to apply the rule to. The error message when the rule fails. Either 'create' or 'update' or a callable that returns true when the validation rule should be applied.
Returns	$this
Description	Add a notBlank rule to a field.