fastapi/fastapi/datastructures.py

from typing import (
    Any,
    BinaryIO,
    Callable,
    Dict,
    Iterable,
    Optional,
    Type,
    TypeVar,
    cast,
)

from fastapi._compat import (
    PYDANTIC_V2,
    CoreSchema,
    GetJsonSchemaHandler,
    JsonSchemaValue,
    with_info_plain_validator_function,
)
from starlette.datastructures import URL as URL  # noqa: F401
from starlette.datastructures import Address as Address  # noqa: F401
from starlette.datastructures import FormData as FormData  # noqa: F401
from starlette.datastructures import Headers as Headers  # noqa: F401
from starlette.datastructures import QueryParams as QueryParams  # noqa: F401
from starlette.datastructures import State as State  # noqa: F401
from starlette.datastructures import UploadFile as StarletteUploadFile
from typing_extensions import Annotated, Doc  # type: ignore [attr-defined]


class UploadFile(StarletteUploadFile):
    """
    A file uploaded in a request.

    Define it as a *path operation function* (or dependency) parameter.

    If you are using a regular `def` function, you can use the `upload_file.file`
    attribute to access the raw standard Python file (blocking, not async), useful and
    needed for non-async code.

    Read more about it in the
    [FastAPI docs for Request Files](https://fastapi.tiangolo.com/tutorial/request-files/).

    ## Example

    ```python
    from typing import Annotated

    from fastapi import FastAPI, File, UploadFile

    app = FastAPI()


    @app.post("/files/")
    async def create_file(file: Annotated[bytes, File()]):
        return {"file_size": len(file)}


    @app.post("/uploadfile/")
    async def create_upload_file(file: UploadFile):
        return {"filename": file.filename}
    ```
    """

    file: Annotated[
        BinaryIO,
        Doc("The standard Python file object (non-async)."),
    ]
    filename: Annotated[Optional[str], Doc("The original file name.")]
    size: Annotated[Optional[int], Doc("The size of the file in bytes.")]
    headers: Annotated[Headers, Doc("The headers of the request.")]
    content_type: Annotated[
        Optional[str], Doc("The content type of the request, from the headers.")
    ]

    async def write(
        self,
        data: Annotated[
            bytes,
            Doc(
                """
                The bytes to write to the file.
                """
            ),
        ],
    ) -> None:
        """
        Write some bytes to the file.

        You normally wouldn't use this from a file you read in a request.

        To be awaitable, compatible with async, this is run in threadpool.
        """
        return await super().write(data)

    async def read(
        self,
        size: Annotated[
            int,
            Doc(
                """
                The number of bytes to read from the file.
                """
            ),
        ] = -1,
    ) -> bytes:
        """
        Read some bytes from the file.

        To be awaitable, compatible with async, this is run in threadpool.
        """
        return await super().read(size)

    async def seek(
        self,
        offset: Annotated[
            int,
            Doc(
                """
                The position in bytes to seek to in the file.
                """
            ),
        ],
    ) -> None:
        """
        Move to a position in the file.

        Any next read or write will be done from that position.

        To be awaitable, compatible with async, this is run in threadpool.
        """
        return await super().seek(offset)

    async def close(self) -> None:
        """
        Close the file.

        To be awaitable, compatible with async, this is run in threadpool.
        """
        return await super().close()

    @classmethod
    def __get_validators__(cls: Type["UploadFile"]) -> Iterable[Callable[..., Any]]:
        yield cls.validate

    @classmethod
    def validate(cls: Type["UploadFile"], v: Any) -> Any:
        if not isinstance(v, StarletteUploadFile):
            raise ValueError(f"Expected UploadFile, received: {type(v)}")
        return v

    @classmethod
    def _validate(cls, __input_value: Any, _: Any) -> "UploadFile":
        if not isinstance(__input_value, StarletteUploadFile):
            raise ValueError(f"Expected UploadFile, received: {type(__input_value)}")
        return cast(UploadFile, __input_value)

    if not PYDANTIC_V2:

        @classmethod
        def __modify_schema__(cls, field_schema: Dict[str, Any]) -> None:
            field_schema.update({"type": "string", "format": "binary"})

    @classmethod
    def __get_pydantic_json_schema__(
        cls, core_schema: CoreSchema, handler: GetJsonSchemaHandler
    ) -> JsonSchemaValue:
        return {"type": "string", "format": "binary"}

    @classmethod
    def __get_pydantic_core_schema__(
        cls, source: Type[Any], handler: Callable[[Any], CoreSchema]
    ) -> CoreSchema:
        return with_info_plain_validator_function(cls._validate)


class DefaultPlaceholder:
    """
    You shouldn't use this class directly.

    It's used internally to recognize when a default value has been overwritten, even
    if the overridden default value was truthy.
    """

    def __init__(self, value: Any):
        self.value = value

    def __bool__(self) -> bool:
        return bool(self.value)

    def __eq__(self, o: object) -> bool:
        return isinstance(o, DefaultPlaceholder) and o.value == self.value


DefaultType = TypeVar("DefaultType")


def Default(value: DefaultType) -> DefaultType:
    """
    You shouldn't use this function directly.

    It's used internally to recognize when a default value has been overwritten, even
    if the overridden default value was truthy.
    """
    return DefaultPlaceholder(value)  # type: ignore