So, okay i tried a lot of rules from validation docs but all give me same error saying
Array to string conversion
Here is how I add
Update: You are now able to use the Rule class instead of imploding values yourself as described in the correct answer. Simply do:
['someProperty' => ['required', Rule::in(['needed', 'stuff'])]];
As mentioned in the 'validating arrays' section in the documentation: https://laravel.com/docs/5.6/validation#validating-arrays