Exception: A Parser can not resolve classes when using `$ref` if references are nested

Describe the bug Parser can not resolve classes when using $ref if the path is nested even though the reference is a valid json pointer.

File "c:\users\sonali.ingale\appdata\local\programs\python\python39\lib\site-packages\datamodel_code_generator\__main__.py", line 281, in main
    generate(
  File "c:\users\sonali.ingale\appdata\local\programs\python\python39\lib\site-packages\datamodel_code_generator\__init__.py", line 259, in generate
    results = parser.parse()
  File "c:\users\sonali.ingale\appdata\local\programs\python\python39\lib\site-packages\datamodel_code_generator\parser\base.py", line 332, in parse
    _, sorted_data_models, require_update_action_models = sort_data_models(
  File "c:\users\sonali.ingale\appdata\local\programs\python\python39\lib\site-packages\datamodel_code_generator\parser\base.py", line 110, in sort_data_models
    return sort_data_models(
  File "c:\users\sonali.ingale\appdata\local\programs\python\python39\lib\site-packages\datamodel_code_generator\parser\base.py", line 110, in sort_data_models
    return sort_data_models(
  File "c:\users\sonali.ingale\appdata\local\programs\python\python39\lib\site-packages\datamodel_code_generator\parser\base.py", line 110, in sort_data_models
    return sort_data_models(
  [Previous line repeated 97 more times]
  File "c:\users\sonali.ingale\appdata\local\programs\python\python39\lib\site-packages\datamodel_code_generator\parser\base.py", line 158, in sort_data_models
    raise Exception(f'A Parser can not resolve classes: {unresolved_classes}.')
Exception: A Parser can not resolve classes: [class: Person references: {'Dog', 'Cat'}]

To Reproduce

Example schema:

{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "title": "Person",
    "type": "object",
    "properties": {
        "name": {
            "title": "name",
            "type": "string"
        },
        "pet": {
            "title": "pet",
            "type": "object",
            "oneOf": [
                {
                    "$ref": "#/definitions/Pets/Cat"
                },
                {
                    "$ref": "#/definitions/Pets/Dog"
                }
            ]
        }
    },
    "definitions": {
        "Pets": {
            "Cat": {
                "title": "Cat",
                "type": "object",
                "required": [
                    "pet_type",
                    "hunts",
                    "age"
                ],
                "properties": {
                    "pet_type": {
                        "enum": [
                            "Cat"
                        ]
                    },
                    "hunts": {
                        "type": "boolean"
                    },
                    "age": {
                        "type": "string"
                    }
                }
            },
            "Dog": {
                "title": "Dog",
                "type": "object",
                "required": [
                    "pet_type",
                    "bark",
                    "breed"
                ],
                "properties": {
                    "pet_type": {
                        "enum": [
                            "Dog"
                        ]
                    },
                    "bark": {
                        "type": "boolean"
                    },
                    "breed": {
                        "type": "string"
                    }
                }
            }
        }
    },
    "additionalProperties": false
}

Used commandline:

$ datamodel-codegen --input pets.json --input-file-type=jsonschema --output pets.py

Expected behavior I was expecting following things which is working when I do not encapsulate “Cat” and “Dogs” inside “Pet”.

• Create the classes “Cat” and “Dog”
• Add “pet” attribute with Union of “Cat” and “Dog”

Version:

• windows
• Python version: 3.9.0
• datamodel-code-generator version:0.6.18

Additional context I tried to pull the code and run this example but I am getting the same error. I have few large schemas which are encapsulating references for readability. After editing the schema according to datamodel-code-generator, it works wonderfully 👍 . Thanks for this module.

[MikeZaharov]

@koxudaxi I’ve just tested and it works correctly. Thank you) This library is awesome!)

[koxudaxi]

@sonali686 I fixed it!! And I have released a new version as 0.6.22.