Validation call according Checkbox check in Laravel 5.5 - laravel-5.5

Question

I have one checkbox and two input fields I want if I check checkbox then second (b) input box is require otherwise first (a) input field in require.
<input type="checkbox" name="try" id="try" value="on">
<input type="text" name="a" id="a">
<input type="text" name="b" id="b">
$validator = Validator::make($request->all(), [
'a' => 'nullable|required_if:try,off',
'b' => 'nullable|required_if:try,on'
]);
Try but not success. Please Help. Edit [Typo in required_if]

Answer 1

First, you need to define rule on try input like :
$this->validate($request, [
'a' => 'partialARequired',
'b' => 'partialBRequired'
]);
Then you must define your partialRequired method's definition:
class customValidation extends Validator
{
public function validatePartialARequired($attribute, $value, $parameters)
{
if(!in_array('try',$this->data) && empty($value))
{
return false;
}
return true;
}
public function validatePartialBRequired($attribute, $value, $parameters)
{
if(in_array('try',$this->data) && empty($value))
{
return false;
}
return true;
}
}