Please how do I solve this problem?

See more:

PHP

Laravel

public function register_new_member(Request $request)
{

$user =new User;
$sponsor=User::where('username',$request['sponsor']);
$user->username=$request['username'];
$user->fName=$request['fName'];
$user->lName=$request['lName'];
$user->gender=$request['gender'];
$user->mobile_number=$request['phone'];
$user->join_date=date('Y-m-d');
if($this->check_under_user($sponsor->id)==false){
session(['status'=>'fail_admin']);
session(['message'=>'Can not register new member! You exceeded system depth']);
return view('pages.admin.registration.register');
}
else{
$value=$this->check_under_user($sponsor->id);
$user->upline_id=$value["upline_id"];
$user->sameline_no=$value["sameline_no"];
$user->level_no=$value["level_no"];
$user->path=User::where('id',$value["upline_id"])->first()->path.$value["sameline_no"];
$user->email=$request['email'];
$user->country=$request['country'];
$user->state=$request['state'];
$user->address=$request['address'];
$user->zip_code=$request['zipcode'];
$user->city=$request['city'];
$user->password=bcrypt($request['password']);

$user->save();

return view('pages.admin.genealogy.matrix');
}
}

What I have tried:

it is giving me this error:

Undefined property: Illuminate\Database\Eloquent\Builder::$id

I have tried using get() and first() but it's still showing me error:

Trying to get property 'id' of non-object