JSON schemas output references rather than primitive types for Unions

[syastrov]

• typical version: 2.0.28
• Python version: 3.8.1
• Operating System: macOS Catalina

Description

When trying to get the JSON schema for a TypedDict, some of the properties have a reference to a "#/definitions/NoneType" and "#/definitions/Str" (which doesn't exist) rather than using "type": "string" or "type": "null".

I assume the problem generalizes to all union types, not just Optionals.

Apparently, this only starts occurring when there are at least 3 fields that are Optionals on the type.

I have a PR forthcoming which should fix this.

What I Did

Ran the following script:

import json
from typing import TypedDict, Optional
import typic


class Foo(TypedDict):
    a: Optional[str]
    b: Optional[str]
    c: Optional[str]


print(json.dumps(typic.schema(Foo, primitive=True), indent=2))

Output

{
  "type": "object",
  "title": "Foo",
  "properties": {
    "b": {
      "title": "B",
      "anyOf": [
        {
          "type": "string"
        },
        {
          "type": "null"
        }
      ]
    },
    "c": {
      "title": "C",
      "anyOf": [
        {
          "type": "string"
        },
        {
          "type": "null"
        }
      ]
    },
    "a": {
      "title": "A",
      "anyOf": [
        {
          "$ref": "#/definitions/Str"
        },
        {
          "$ref": "#/definitions/NoneType"
        }
      ]
    }
  },
  "additionalProperties": false,
  "required": [
    "b",
    "c",
    "a"
  ],
  "definitions": {}
}

All three properties should have had the same type:

      "anyOf": [
        {
          "type": "string"
        },
        {
          "type": "null"
        }
      ]