Required Optional (nullable) fields exported as non-nullable with Python 3.10

[danelkay93]

From Python 3.10 onwards Type | None is supposed to be preferred over Optional[Type]

pydantic's documentation gives a Python 3.10+ code example for a Required field which is also "Optional" (can receive None as a value).

Versions

• Python 3.10.4
• pydantic 1.10.2
• pydantic-to-typescript 1.0.10:
• json-schema-to-typescript 1.2.2 (note: "strictNullChecks": true is set in the library's tsconfig.json)

To Reproduce

1. Define the following pydantic model:

from pydantic import BaseModel, Field

class ExampleItem(BaseModel):
    nullable: str | None
    optional: Optional[str]
    required_nullable: str | None = ...
    required_nullable_alternate: str | None = Field(...)

2. Export ExampleItem with pydantic2js and receive the result:

export interface ExampleItem{
  nullable?: string;
  optional?: string;
  required_nullable: string;
  required_nullable_alternate: string;
}

Expected Result:

export interface ExampleItem{
  nullable?: string;
  optional?: string;
  required_nullable: string | null;
  required_nullable_alternate: string | null;
}

Notes:

Wouldn't tsconfig with strictNullChecks enabled require nullable notation for a Required Optional pydantic field, considering it could contain None?

I'm not well-versed in TypeScript, but from what I understand, it's acceptable to have | null type annotations (if somewhat unusual), and in this case, it would make Python's responses much clearer for those handling them in TypeScript.

Please correct me if I'm mistaken, as my knowledge of TypeScript might be lacking.

Thanks for the amazing work on the package, it's incredibly useful!

[danelkay93]

This seems to be an unresolved issue in pydantic with BaseModel.schema_json and the JSON Schema specification it supports. There are multiple workarounds mentioned in the issue I linked