Ndtyjky

I am trying to a build a User-class function with an SQLAlchemy query inside that allows me to count the User-records on different tables (based on his id). To avoid multiple function codings, I tried to define a generic function where I receive the db.modell class as a parameter from a Jinja2 call like:

{{ current_user.count('Customer') }}

or

{{ current_user.count('Player') }}

But I end up in errors that Python does not interpret the given class_name parameter as a real Class. He complains that class_name doesn't have a function id.
Of course I could specify specific User Functions with a specific query for each class but I tried to avoid those duplicate codings.

Any ideas on how to deal with this?

class User(db.Model): 

  __tablename__='user'

  id = Column(Integer, primary_key=True)





  def count(self, class_name): 

        s = db.session()

        count = s.query(class_name).filter(class_name.id == self.id).count()

        return count



class Player(db.Model):

   __tablename__='player'

   id = Column(Integer, primary_key=True)



class Customer(db.Model):

   __tablename__='Customer'

   id = Column(Integer, primary_key=True)

Thanks in advance

Michael

It is better to pass the class itself to the function like this:

 def count(self, class_): 

    s = db.session()

    count = s.query(class_).filter(class_.id == self.id).count()

    return count

But if you have to pass a class name for some reason, you can do something like this:

 def count(self, class_name):

    class_ = {

        'player':Player,

        'customer':Customer,

    }[class_name.lower()]



    s = db.session()

    count = s.query(class_).filter(class_.id == self.id).count()

    return count

it is not very different but you can do this.

There is also another way, but I don't recommend this:

 def count(self, class_name):

    class_ = globals()[class_name]



    s = db.session()

    count = s.query(class_).filter(class_.id == self.id).count()

    return count

this way will just work if everything exists in global scope.
read about globals Here

note that:

1. Careful to not use class as a name of a variable, class is predefined. use something else like class_




2. It will raise key errorif you pass a wrong class name in second way. you can handle it with try and except.