Laravel "same" code different results - laravel

Question

I'm trying to guess what's different in this short code but I can't. One works an the other one returns:
Undefined property: Illuminate\Database\Eloquent\Builder::$join_books
First method, this one throws error:
public function selectBook(){
try{
BookUser::create(Input::all());
if(!BookUser::userJoinBooks()){
$user = User::eloquentUser();
$user->join_books = 1;
$user->save();
}
MyHelpers::sendSessionFlashMessages('El libro ha sido seleccionado', 'bg-success');
}
catch (Exception $e) {
$message = MyHelpers::exceptionCatch($e);
MyHelpers::sendSessionFlashMessages($message['message'], $message['css-class']);
}
return Redirect::back();
}
Two lines after this one I have the unselect method, looks like the same, but works fine:
public function unselectBook(){
try{
$book_user = BookUser::find(Input::get('id'));
$book_user->delete();
if(BookUser::userBooksCount() == 0){
$user = User::eloquentUser();
$user->join_books = 0;
$user->save();
}
MyHelpers::sendSessionFlashMessages('El libro ha sido eliminado', 'bg-success');
}
catch (Exception $e) {
$message = MyHelpers::exceptionCatch($e);
MyHelpers::sendSessionFlashMessages($message['message'], $message['css-class']);
}
return Redirect::back();
}
If I remove from SelectBook method "!BookUser::userJoinBooks()" in the if statement and use if(1) for example, it work's. I dont undestand why if I make the $user asigment after this static method it could be influence it.
This is the static method code:
public static function userJoinBooks($id = null){
$user_id = $id === null ? Sentry::getUser()->getId(): $id;
return User::where('id',$user_id)->join_books == 0 ? false : true;
}
And the other one too, may be help:
public static function userBooksCount($id = null){
$user_id = $id === null ? Sentry::getUser()->getId(): $id;
return BookUser::where('user_id',$user_id)->count();
}
And this is the eloquentUser method:
public static function eloquentUser(){
$sentry_user = Sentry::getUser();
return $user = User::findOrFail($sentry_user->id);
}
Really a can't remenber why I use this method, I soppose not to use Sentry::getUser in my code that if at some point I will use another user's library.
Thanks :)

Answer 1

The problem is this part of your code:
return User::where('id',$user_id)->join_books == 0 ? false : true;
I suppose you would want to use something like:
return User::findOrFail($user_id)->join_books == 0 ? false : true;