Docs are incorrect regarding UploadFile

[holyoaks]

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Example Code

from fastapi import UploadFile

file_name = 'test.png'
file_path = 'test.png'

with open(file_path, "rb") as f:
    file=UploadFile(
        filename=file_name, file=f.read(), content_type="image/png"
    )
)

Description

1. Docs here specify UploadFile has a content_type attribute, which it used to
2. Running the code above with any file throws TypeError: UploadFile.__init__() got an unexpected keyword argument 'content_type'
3. Actual Starlette code (datastructures.py) does not expect content_type:

def __init__(
        self,
        file: typing.BinaryIO,
        *,
        size: typing.Optional[int] = None,
        filename: typing.Optional[str] = None,
        headers: "typing.Optional[Headers]" = None,
    )

Docs need to be updated to accurately reflect changes to Starlette

Operating System

Linux

Operating System Details

No response

FastAPI Version

0.100.0

Python Version

3.11

Additional Context

No response

[mateoradman]

Hi @holyoaks,

I believe what is stated in the docs is absolutely correct. That is, an instance of an UploadFile indeed has a content_type attribute. Having an attribute does not imply that UploadFile accepts content_type in the __init__ method.

Looking into the signature of the UploadFile class one can see that a content_type is a property method. This means that this attribute content_type is calculate on the fly every time you access some_file.content_type attribute.

class UploadFile:
    """
    An uploaded file included as part of the request data.
    """

    def __init__(
        self,
        file: typing.BinaryIO,
        *,
        size: typing.Optional[int] = None,
        filename: typing.Optional[str] = None,
        headers: "typing.Optional[Headers]" = None,
    ) -> None:
        self.filename = filename
        self.file = file
        self.size = size
        self.headers = headers or Headers()

    @property
    def content_type(self) -> typing.Optional[str]:
        return self.headers.get("content-type", None)

[holyoaks]

Hmm, fair enough. It was an unexpected change, as previously the Starlette code did accept content_type.