如何使用Laravel 5.2中的if else条件更新表值

Question

I am adding permission values using this function in My Controller.

public function addPermission(Request $request, $id,  Permission $permission)
    {
         $this->validate($request, [
            'status'   => 'required'


        ]);

        $permission = new Permission;

        $permission->status = $request->input('status');
        $permission->project_id       = $id;
        $permission->collaborator_id =  $request->input('cid');
        $permission->save();
        return redirect()->back()->with('info','Permission has been added to your Collaborator successfully');
}

How can I write update code here using if else condition when I change permission value?