tuple types are generated as containing `unknown`

[nneonneo]

Consider the following simple model:

from pydantic import BaseModel

class Sprite(BaseModel):
    path: str | None
    crop: tuple[int, int, int, int]
    hotspot: tuple[int, int]

Running uvx --from 'pydantic-to-typescript>=2' pydantic2ts --module test.py --output test.ts produces

/* tslint:disable */
/* eslint-disable */
/**
/* This file was automatically generated from pydantic models by running pydantic2ts.
/* Do not modify it by hand - just update the pydantic models and then re-run the script
*/

export interface Sprite {
  path: string | null;
  /**
   * @minItems 4
   * @maxItems 4
   */
  crop: [unknown, unknown, unknown, unknown];
  /**
   * @minItems 2
   * @maxItems 2
   */
  hotspot: [unknown, unknown];
}

The expected behaviour is that the tuples are encoded as e.g. [number, number, number, number].

[SpectorCole]

I am experiencing this as well with my project's tuple-types

[SpectorCole]

TLDR

When a python-tuple is translated to a json-schema obj using model_json_schema(mode="serialization"), it types the values using the "prefixItems" key, which json2ts doesn't handle correctly.

Long version:

After doing some testing, it looks like pydantic is creating the json-schema tuples using the "prefixItems" key for the types, i.e.:

# models.py


from pydantic import BaseModel


from typing import Tuple

class Test(BaseModel):
    t: Tuple[str, int]

creates a schema.json of:

{
  "$defs": {
    "Test": {
      "additionalProperties": false,
      "properties": {
        "t": {
          "maxItems": 2,
          "minItems": 2,
          "prefixItems": [
            {
              "type": "string"
            },
            {
              "type": "integer"
            }
          ],
          "type": "array"
        }
      },
      "required": [
        "t"
      ],
      "title": "Test",
      "type": "object"
    }
  },
  "properties": {
    "Test": {
      "$ref": "#/$defs/Test"
    }
  },
  "required": [
    "Test"
  ],
  "title": "_Master_",
  "type": "object"
}

if i run this schema.json through json2ts (either automatically though the script in this repo, or manually using npx json-schema-to-typescript schema.json it outputs the following (bad) typescript:

export interface Test {
  /**
   * @minItems 2
   * @maxItems 2
   */
  t: [unknown, unknown];
}

If I manually edit the schema.json to use "items" instead of "prefixItems", so it becomes:

{
  "$defs": {
    "Test": {
      "additionalProperties": false,
      "properties": {
        "t": {
          "maxItems": 2,
          "minItems": 2,
          "items": [
            {
              "type": "string"
            },
            {
              "type": "integer"
            }
          ],
          "type": "array"
        }
      },
      "required": [
        "t"
      ],
      "title": "Test",
      "type": "object"
    }
  },
  "properties": {
    "Test": {
      "$ref": "#/$defs/Test"
    }
  },
  "required": [
    "Test"
  ],
  "title": "_Master_",
  "type": "object"
}

i can run npx json-schema-to-typescript schema.json to get a wanted typescript type of

export interface Test {
  /**
   * @minItems 2
   * @maxItems 2
   */
  t: [string, number];
}

My thoughts (not a representative of pydantic-2-typescript)

I would argue that this is actually a json2ts problem, as "prefixItems" is the correct value for tuples; however, because the output typescript is a correct tuple typing, to get this repo to work it may be beneficial to swap to using "items" for now, and once json2ts fixes its bug to swap back to using the (correct) "prefixItems" key. The big issue with doing the temporary swap is that this is a default output from pydantic when using Tuple, so you would have to manually go in to the generated json to swap this out (similar to whats done in _clean_json_schema)

[SpectorCole]

Good news - you can get around this if you use the patch-package method from this json2ts issue thread -- bcherny/json-schema-to-typescript#543. I manually made the changes outlined in their patch-file (important to remember to manually update the compiled .js in your dist folder) and applied it and it worked for me