How to get objects of a class with a function inside the class?-CodePudding

I have a database class that stores the objects in database.py:

class Database(dict):
    def get_objects_by_object_type(self, object_type):
        # get a list of objects based on object type


db = Database()

and then I have these two classes in models.py:

class IdentifiableObject(object):
    def __init__(self, object_id):
        self.object_id = object_id
        self.object_type = self.__class__.__name__.lower()

    @classmethod
    def get_object_type(cls):
        return f"{cls.__name__.lower()}"


class Ingredient(IdentifiableObject):
    def __init__(self, object_id, unsuitable_diets=[]):
        super(Ingredient, self).__init__(object_id=object_id)
        self.unsuitable_diets = unsuitable_diets

How can I get objects by type: for example, if I pass an object of type ingredient it should get all ingredients and return it.

# Ingredient.get_object_type() is equal to 'ingredient'


ingredients = db.get_objects_by_object_type(object_type=Ingredient.get_object_type())

CodePudding user response：

I assume this snippet will work for you. Leave comments if I misunderstand your question.

class IdentifiableObject(object):
    def __init__(self, object_id):
        self.object_id = object_id
        self.object_type = self.__class__.__name__.lower()

    @classmethod
    def get_object_type(cls):
        return f"{cls.__name__.lower()}"


class Ingredient(IdentifiableObject):
    def __init__(self, object_id, unsuitable_diets):  # don't use mutable value as default argument value.
        super(Ingredient, self).__init__(object_id=object_id)
        if unsuitable_diets is None:
            unsuitable_diets = []
        self.unsuitable_diets = unsuitable_diets


class Database(dict):
    def get_objects_by_object_type(self, object_type):
        return [values for values in self.values() if values.get_object_type() == object_type]


if __name__ == '__main__':
    db = Database({
        "1": IdentifiableObject(1),
        "2": Ingredient(2),
        "3": Ingredient(3),
    })
    ingredients = db.get_objects_by_object_type(Ingredient.get_object_type())
    identifiable_objects = db.get_objects_by_object_type(IdentifiableObject.get_object_type())
    print(ingredients)
    print(identifiable_objects)

Outputs:

[<__main__.Ingredient object at 0x10a933880>, <__main__.Ingredient object at 0x10a933820>]
[<__main__.IdentifiableObject object at 0x10a9338e0>]

CodePudding user response：

This is one way to identify objects by type:

class MyClass:
    pass

some_objects = [5, "string", MyClass()]

for o in some_objects:
    if type(o) == MyClass:
        print("Found item of MyClass")