[typing BUG] PatchDict Type checking error

[sxoinas12]

Describe the bug

when using PatchDict I do get the below error when I perform my type checking:

Run Basedpyright type checking...........................................Failed
- hook id: basedpyright
- exit code: 1

Type "dict[Unknown, Unknown]" is already specialized

Example:

i have the below schema

from ninja import Schema, PatchDict

class UpdateTextSectionData(Schema):
    title: str
    content: str
    event_id: uuid.UUID

@text_sections_api.patch(
    "/{text_section_id}",
)
def update_text_section(
    request: WSGIRequest,
    text_section_id: uuid.UUID,
    text_section_data: PatchDict[UpdateTextSectionData], # error is being raised for this line
)

when using it in my view with PatchDict as described in your documentation I do get the above type error, which i believe it's expected since you already it have it as an annotated type here

Is there a mistake in your documentation ? I would expect this to do what it describes and make my fields optional.

Versions:

• Python version: 3.13.0
• Django version: 5.1.5
• Django-Ninja version: 1.4.1
• Pydantic version: 2.11.3

[vitalik]

@sxoinas12 could you share what do you use for typechecing (exact version and command you are running to type check it ? )

[sxoinas12]

@vitalik Thanks for coming back to this .

I am using "basedpyright>=1.28.1", and the command to test this is simply basedpyright
Our settings are the below

[tool.pyright]
pythonPlatform = "Linux"
reportUnsupportedDunderAll  = "none"
typeCheckingMode            = "standard"    # "off", "basic", "standard", "strict"

simply by running basedpyright you can reproduce -> error: Type "dict[Unknown, Unknown]" is already specialized

[Ige-kun]

This is also reproducible with the upstream pyright using its latest version (1.1.400) with the configuration
typeCheckingMode = "standard" (the default).

[vitalik]

@Ige-kun @sxoinas12 - can you check if placing this before you code will work ?

from typing import TYPE_CHECKING, Generic, Any, TypeVar

if TYPE_CHECKING:
    T = TypeVar('T')
    class PatchDict(dict[Any, Any], Generic[T]):
        pass

[khurramshahzad456]

I tried above code and start getting an other type error

[sxoinas12]

Hi @vitalik. Thanks for coming back. I tried your suggested solution.

here is the full snippet and the error

from typing import TYPE_CHECKING, Generic, Any, TypeVar
from ninja import Schema, PatchDict

if TYPE_CHECKING:
    T = TypeVar("T")

    class PatchDict(dict[Any, Any], Generic[T]):
        pass

class UpdateTextSectionData(Schema):
    title: str
    content: str
    event_id: uuid.UUID


@text_sections_router.patch(
    "events/{event_id}/text-sections/{text_section_id}",
    response={204: SuccessHullAPIResponse, 403: FailureHullAPIResponse},
)
def update_event_text_section(
    request: WSGIRequest,
    event_id: uuid.UUID,
    text_section_id: uuid.UUID,
    text_section_payload: PatchDict[UpdateTextSectionData],
) -> tuple[int, HullAPIResponse]:

Error

/Users/konstantinosschoinas/work.nosync/hull/backend/src/text_sections/update_text_section/views.py
  /Users/konstantinosschoinas/work.nosync/hull/backend/src/text_sections/update_text_section/views.py:22:27 - error: Type "PatchDict" is not assignable to declared type "type[PatchDict[T@PatchDict]]"
    Type "Annotated" is not assignable to type "type[PatchDict[T@PatchDict]]" (reportAssignmentType)
  /Users/konstantinosschoinas/work.nosync/hull/backend/src/text_sections/update_text_section/views.py:61:36 - error: Cannot access attribute "dict" for class "PatchDict[UpdateTextSectionData]"
    Attribute "dict" is unknown (reportAttributeAccessIssue)
2 errors, 0 warnings, 0 notes

Notice the later error comes because i try to do **text_section_payload.dict later in the code.

[nikatlas]

@vitalik

I think the issue is that you annotate the PatchDict as a dictionary.
The PatchDict is actually a descriptor that returns a dictionary based on a Schema so it is more like a Generic of dict (type of PatchDict[ ANY_SCHEMA ] -> dict ).

I tried this and works with pyright.

type PatchDict[T: Schema] = Annotated[dict, "<PatchDict>"]

It does look incomplete to me though or not the proper way to type this descriptor. Ideally the PatchDictUtil class should be typed such that the custom if TYPE_CHECKING is not needed. But I know that typing descriptors is not easy.

If I find something more precise I will let you know. Let me know if you know how this typing can be achieved in a more complete way.

Note: This may only work on python 3.12 as generics types where introduced then.

[nikatlas]

@vitalik I just realised your snippet above is equivalent to my snippet provided above and backwards compatible to older versions.

The issue mentioned by the other guys is because the type definition is declared twice both inside the library and then they try to overwrite it.

I edited the library internally and it works like a charm.

Could we merge your fix and make a release?

[vitalik]

@nikatlas @sxoinas12 @khurramshahzad456 - can you check against this branch ? https://github.com/vitalik/django-ninja/tree/1441-patch-dict-type-check

[sxoinas12]

I tested it with

uv pip install git+https://github.com/vitalik/django-ninja.git@4f0bbbc61f5d9bd4100c9965a020edce4f93bf9e

(.venv) konstantinosschoinas@Konstantinoss-MacBook-Pro backend % basedpyright
0 errors, 0 warnings, 0 notes

[sxoinas12]

Fixed with this one Thank you