datamodel-code-generator

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Describe the bug When converting JsonSchema, if a field is defined as not required and with a null type, the converter creates a default None value for this field To Reproduce

Example schema:

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "definitions": {
    "a": {
      "type": "object",
      "required": [
        "b"
      ],
      "properties": {
        "c": {
          "title": "c",
          "type": [
            "string",
            "null"
          ]
        },
        "b": {
          "title": "b",
          "type": [
            "string",
            "null"
          ]
        }
      },
      "additionalProperties": false
    }
  },
  "$ref": "#/definitions/a"
}

python
# generated by datamodel-codegen:
#   filename:  request_schema.json
#   timestamp: 2022-05-22T13:39:44+00:00

from __future__ import annotations

from typing import Optional

from pydantic import BaseModel, Extra, Field


class A(BaseModel):
    class Config:
        extra = Extra.forbid

    c: Optional[Optional[str]] = Field(None, title='c')
    b: Optional[str] = Field(..., title='b')


class Model(BaseModel):
    __root__: A

Used commandline:

$ datamodel-codegen --input <above json schema> --output <python file>

Expected behavior

python 

# generated by datamodel-codegen:
#   filename:  request_schema.json
#   timestamp: 2022-05-22T13:39:44+00:00

from __future__ import annotations

from typing import Optional

from pydantic import BaseModel, Extra, Field


class A(BaseModel):
    class Config:
        extra = Extra.forbid

    c: Optional[Optional[str]] = Field(..., title='c')
    b: Optional[str] = Field(..., title='b')


class Model(BaseModel):
    __root__: A

Version:

• OS: macos
• Python version: 3.8.6
• datamodel-code-generator version: datamodel-code-generator==0.12.0

Additional context Ive tried also with --strip-default-none, and the output is the same.

@alonbeilis I'm sorry for my late reply.

    c: Optional[Optional[str]] = Field(..., title='c')

I think the field is required in Pydantic. But, you defined the field as not required in your schema 🤔

I'm encountering a similar problem: A field i set to nullable in the schema:

...
"forretningshændelse": {
	"description": "EAID_1CE948DD_FC3D_4638_8913_A2D35A00F64D",
	"type": ["string", "null"]
},
...

But the resulting generated code is:

...
    forretningshændelse: Optional[Optional[str]] = Field(
        None, description='EAID_1CE948DD_FC3D_4638_8913_A2D35A00F64D'
    )
...

Expected output:

...
    forretningshændelse: Optional[str] = Field(
        None, description='EAID_1CE948DD_FC3D_4638_8913_A2D35A00F64D'
    )
...

Why is it wrapped twice as Optional? :thinking:

I solved it manually by substituting ["string", "null"] for "string".

@nymann I'm sorry for my too-late reply.
I have released the PR as 0.15.0 Thank you very much!!