How can I validate multiple form with one request file?

I have three form and I want to validate them within one request file.How to check the form identity within the rules method.I'm confused.I wrote this but It didn't work.here is my code

 //rules method
    public function rules()
 {

   switch ($this->check())
    {
        case 'personal':
            return ['fanme'=>'required'];
            break;

        case 'career':
            return ['career'=>'required'];
            break;  

        case 'summary':
            return ['summary_info'=>'required'];
            break; 

        default:
             return [];
            break;
   }
}


//my own method
public function check()
 {
  return $this->input('form_identity');
 }
//form field
<input type="hidden" value="personal" 
 class="form-control required" 
 name="form_identity"/>

via Chebli Mohamed