init

app/ValidationRules/CronRule.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace App\ValidationRules;
+
+use Cron\CronExpression;
+use Illuminate\Contracts\Validation\Rule;
+
+class CronRule implements Rule
+{
+    public function passes($attribute, $value): bool
+    {
+        return CronExpression::isValidExpression($value);
+    }
+
+    public function message(): string
+    {
+        return __('Invalid frequency');
+    }
+}