Invalid enum names not properly handled (e.g.: "mro")

[DavideWalder]

Describe the bug
Enum member names can't be mro, since this clashes with the method resolution order method.

To Reproduce

Example schema:

{
  "type": "array",
  "items": {
    "type": "object",
    "properties": {
      "enum_with_invalid_value": {
        "type": "string",
        "enum": ["mro"]
      }
    }
  }
}

Used commandline:

datamodel-codegen  --input schema.json  --input-file-type jsonschema --output model.py
python -c "import model" # ValueError: Invalid enum member name: mro

Expected behavior
The name should be adapted. According to PEP-8, the preferred solution is to suffix with an underscore ("mro_" instead of "mro"). Since this is only the enum name it should not have any impact on parsing.

Version:

• OS: MacOS
• Python version: 3.10.4
• datamodel-code-generator version: 0.13.1

[koxudaxi]

@DavideWalder
I have released the new version as 0.13.5
Thank you very much!!

[DavideWalder]

@koxudaxi
I'm testing with 0.17.0 and the issue is still there (same for 0.14.0)

[koxudaxi]

@DavideWalder
I tested your example on my machine.
The result looks good.

$ datamodel-codegen  --input schema.json  --input-file-type jsonschema --output model.py
$ python -c "import model"
$ echo $?                 
0
$ datamodel-codegen --version                                                         
0.17.0

model.py

# generated by datamodel-codegen:
#   filename:  schema.json
#   timestamp: 2023-01-31T13:13:09+00:00

from __future__ import annotations

from enum import Enum
from typing import List, Optional

from pydantic import BaseModel


class EnumWithInvalidValue(Enum):
    mro_ = 'mro'


class ModelItem(BaseModel):
    enum_with_invalid_value: Optional[EnumWithInvalidValue] = None


class Model(BaseModel):
    __root__: List[ModelItem]

Have you tried the other input or the same one?

[DavideWalder]

Found the issue:

input:

openapi: 3.0.3
components:
  schemas:
    TheEnum:
      type: string
      enum:
        - MRO
        - mro

output:

# generated by datamodel-codegen:
#   filename:  datasync.yaml
#   timestamp: 2023-01-31T13:27:19+00:00

from __future__ import annotations

from enum import Enum


class TheEnum(Enum):
    mro = 'MRO'
    mro_ = 'mro'

The underscore is suffixed only when the enum value is lowercase

[koxudaxi]

Thank you for explaining the problem.
I will soon change the result to the one below.

class TheEnum(Enum):
    mro_ = 'MRO'
    mro_1 = 'mro'

[DavideWalder]

Also, this brings up the question of what to do when two entries differ by casing like NAME and name. Probably a clearer solution would be to maintain the casing, as:

class TheEnum(Enum):
    MRO_ = 'MRO'
    mro_ = 'mro'

This would also avoid the issue where changing the order from

openapi: 3.0.3
components:
  schemas:
    TheEnum:
      type: string
      enum:
        - MRO
        - mro

openapi: 3.0.3
components:
  schemas:
    TheEnum:
      type: string
      enum:
        - mro
        - MRO

would change the enum names.

I see that keeping the casing would be a non-backward compatible change though

[koxudaxi]

@DavideWalder
Good point.
I want to avoid changing current behavior.
I reccomend to use --snake-case-field or --capitalise-enum-members

without options

class InvalidEnum(Enum):
    MRO = 'MRO'
    mro_ = 'mro'

--snake-case-field

class InvalidEnum(Enum):
   mro_1 = 'MRO'
   mro_ = 'mro'

--capitalise-enum-members

class InvalidEnum(Enum):
    MRO = 'MRO'
    MRO_ = 'mro'

https://github.com/koxudaxi/datamodel-code-generator/pull/1069/files#diff-440ee6529a7880f5b3f955ee7186af0b603ba307adc6991ea004642878e55182R15-R16

[koxudaxi]

@DavideWalder
I have released the fix version 0.17.1
Thank you very much!!