A Cron expression validator is created in Laravel 5.3. Laravel provides a versatile and extendable Validation class. Introducing new validations is done by registering a validation function with the extend method on the Validation facade. A Cron expression validator is created by utilising a cron-expression parser.
The cron-expression parser used here is the fantastic
cron-expression Composer package
by Michael Dowling.
First, require the Composer package.
composer require mtdowling/cron-expression
Second, extend the
Validator-_class with a cron_expression validation method in the boot method of an appropriate Service Provider (e.g. _AppServiceProvider.php
). Don’t forget to
import
the class:
use Cron\CronExpression;
Then modify the _boot
_function.
* Bootstrap any application services.
* @return void
public function boot()
Validator::extend('cron_expression', function ($attribute, $value, $parameters, $validator) {
return CronExpression::isValidExpression( $value );
It is also possible to put this in a separate package (and separate Service Provider).
Finally, add the translation to the appropriate language files (e.g.
/resources/lang/en/validation.php
):
'cron_expression' => 'The :attribute field contains no valid CRON expression.',
Use the validator like any other validation rule.
$this->validate($request, [
'recurrence' => 'required|cron_expression',
'name' => 'required',
Done already! I enjoy the ease of implementing a new validation rule in Laravel.
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