Search code examples
pythondictionarypeeweeclass-variables

Using python class variables as dict key is good practice?

I wonder if i use class variables as keys in a dictionary can it be considered as good practice? For example, this is object model in peewee.

class Abc:
    name = CharField()
    age = IntegerField()

then i declare a configuration dict for it like this

conf = {Abc.name: Config(listable=False, format_on_edit=True), Abc.age: Config()}

I don't want to use string like name, age as dict keys because i'm afraid of mistyping, and want to make sure that Object/ Model field is valid.

I see Sqlalchemy or Peewee are using condition like where(Abc.name=='abc') or filter(User.age == 25) , not where('name', 'abc') like many other orms from Go or PHP since they don't have class variables.

It's quite good for prevent mistyping. I've tried hash(Abc.name) and it works then class variables are immutable for using as dict keys or not?

Solution

  • You may safely use them. Peewee replaces the field instances you declare as model attributes with special Descriptor objects (which then expose the underlying field instance, which is hashable).

    For instance, when performing an insert or update, you can specify the data using the fields as keys:

    User.insert({User.username: 'charlie'}).execute()