* 🔧 Update sponsors: add Greptile. PR [#14429](https://github.com/fastapi/fastapi/pull/14429) by [@tiangolo](https://github.com/tiangolo).
* 👥 Update FastAPI GitHub topic repositories. PR [#14426](https://github.com/fastapi/fastapi/pull/14426) by [@tiangolo](https://github.com/tiangolo).
* ⬆ Bump markdown-include-variants from 0.0.6 to 0.0.7. PR [#14423](https://github.com/fastapi/fastapi/pull/14423) by [@YuriiMotov](https://github.com/YuriiMotov).

    in another `APIRouter` (ultimately included in the app).

    Read more about it in the
    [FastAPI docs for Bigger Applications - Multiple Files](https://fastapi.tiangolo.com/tutorial/bigger-applications/).

    ## Example

    ```python
    from fastapi import APIRouter, FastAPI

    app = FastAPI()
    router = APIRouter()

from typing import Annotated

import pytest
from fastapi import FastAPI, Query
from fastapi.exceptions import FastAPIDeprecationWarning
from fastapi.testclient import TestClient

from .utils import needs_py310


def get_client():
    app = FastAPI()
    with pytest.warns(FastAPIDeprecationWarning):

        @app.get("/items/")
        async def read_items(
            q: Annotated[str | None, Query(regex="^fixedquery$")] = None,

from typing import Union

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel, ConfigDict


class FooBaseModel(BaseModel):
    model_config = ConfigDict(extra="forbid")


class Foo(FooBaseModel):
    pass


app = FastAPI()


@app.post("/")
async def post(
    foo: Union[Foo, None] = None,
):
    return foo


client = TestClient(app)

from typing import Any

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel, ConfigDict


def test_read_with_orm_mode() -> None:
    class PersonBase(BaseModel):
        name: str
        lastname: str

    class Person(PersonBase):
        @property
        def full_name(self) -> str:
            return f"{self.name} {self.lastname}"

    skip_module_if_py_gte_314()

from fastapi import FastAPI
from fastapi.exceptions import PydanticV1NotSupportedError

with warnings.catch_warnings():
    warnings.simplefilter("ignore", UserWarning)
    from pydantic.v1 import BaseModel


def test_raises_pydantic_v1_model_in_endpoint_param() -> None:
    class ParamModelV1(BaseModel):
        name: str

    app = FastAPI()

    Optional,
    Union,
)
from weakref import WeakKeyDictionary

import fastapi
from fastapi._compat import (
    BaseConfig,
    ModelField,
    PydanticSchemaGenerationError,
    Undefined,
    UndefinedType,
    Validator,
    annotation_is_pydantic_v1,
)
from fastapi.datastructures import DefaultPlaceholder, DefaultType
from fastapi.exceptions import FastAPIDeprecationWarning, PydanticV1NotSupportedError

from datetime import datetime, timezone

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel


def test_pydanticv2():
    from pydantic import field_serializer

    class ModelWithDatetimeField(BaseModel):
        dt_field: datetime

        @field_serializer("dt_field")
        def serialize_datetime(self, dt_field: datetime):

from fastapi import FastAPI, UploadFile
from fastapi._compat import (
    Undefined,
    is_uploadfile_sequence_annotation,
)
from fastapi._compat.shared import is_bytes_sequence_annotation
from fastapi.testclient import TestClient
from pydantic import BaseModel, ConfigDict
from pydantic.fields import FieldInfo

from .utils import needs_py310


def test_model_field_default_required():
    from fastapi._compat import v2

from typing import Optional, Union

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: Optional[str] = None


class ExtendedItem(Item):
    age: int


@app.post("/items/")
def save_union_different_body(item: Union[ExtendedItem, Item]):
    return {"item": item}


client = TestClient(app)