Recursion of Category in Category creates pydantic error

[torogi94]

If hinting to Category with Category , this error occurs:
Exception has occurred: NameError
name 'Category' is not defined

If hinting to Category with "Category" (like you usually do in Python), this error occurs:
Exception has occurred: TypeError
issubclass() arg 1 must be a class

[JR-1991]

Self-Referencing annotations can be handled quite nice with Pedantic (see doc). Whenever you want to reference the self-class in an annotation, simply pass it as a string and it works. Here is an overexagurated example:

import pydantic
import enum
import typing
import json

class CategoryType(pydantic.BaseModel):
    """Recursion is possible when the type is given as a string"""
    
    foo: str
    bar: str
    category: typing.Optional['CategoryType'] = None

# Create recursion objects
category = CategoryType(foo="foo", bar="bar")
top_category = CategoryType(foo="top_foo", bar="top_bar")
toptop_category = CategoryType(foo="toptop_foo", bar="toptop_bar")

# Get them together
category.category = top_category
category.category.category = toptop_category

JSON

{
   "foo": "foo",
   "bar": "bar",
   "category": {
      "foo": "top_foo",
      "bar": "top_bar",
      "category": {
         "foo": "toptop_foo",
         "bar": "toptop_bar",
         "category": null
      }
   }
}

This is by far one of the best libraries I've ever used. Many kudos!