Self-referencing Python object MongoDB Schema
What am I trying to achieve?
The program I am trying to create handles data describing categories of grocery products, like: Milk, Beef, Corn, Local Fruits and such. I plan on storing this data in a MongoDB instance, therefore creating a schema would be nice.
The reason for my problem is that categories have subcategories (Dairy: Milk, Cheese, Yogurt; Meat: Beef, Pork; etc.), resulting in recursive objects.
Python Alone
I've looked up on StackOverflow how one should approach such structures in Python.
class Category():
def _init_(self, name, amount, subcategories = ()):
self.name = name
self.amount = amount
for subcategory in subcategories:
assert isinstance(subcategory, Category)
self.subcategories = subcategories
This seems about right...
The Schema part
...But only until I try to tie it into a schema:
class Category(mongoengine.EmbeddedDocument):
def _init_(self, name, amount, subcategories = ()):
self.name = name
self.amount = amount
for subcategory in subcategories:
assert isinstance(subcategory, Category)
self.subcategories = subcategories
name = mongoengine.StringField(required=True)
amount = mongoengine.FloatField(required=True)
subcategories = mongoengine.EmbeddedDocumentListField(Category, default=None)
meta = {
'db_alias': 'core',
'collection': 'category',
'indexes': [
'name',
'amount',
'subcategories',
],
'ordering': ['-name']
}
Running this code results in an error:
subbcategories = mongoengine.EmbeddedDocumentListField(Category, default=None) NameError: name 'Category' is not defined
I tried referencing the parent category, instead of embedding child categories:
parent_category = mongoengine.ObjectIdField(Category, default=None)
But I still get exactly the same error message:
parent_category = mongoengine.ObjectIdField(Category, default=None)NameError: name 'Category' is not defined
The Question itself
How should I define a schema for a recursive object like this? Is it possible?
