from typing import Annotated

from fastapi import FastAPI, File, UploadFile
from fastapi.responses import HTMLResponse

app = FastAPI()


@app.post("/files/")
async def create_files(files: Annotated[list[bytes], File()]):
    return {"file_sizes": [len(file) for file in files]}


@app.post("/uploadfiles/")
async def create_upload_files(files: list[UploadFile]):
    return {"filenames": [file.filename for file in files]}

Aber es gibt viele Fälle, in denen Sie davon profitieren, `UploadFile` zu verwenden.

## Datei-Parameter mit `UploadFile`

Definieren Sie einen Datei-Parameter mit dem Typ `UploadFile`:

=== "Python 3.9+"

    ```Python hl_lines="14"
    {!> ../../../docs_src/request_files/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

import pytest
from fastapi import FastAPI, File, Form, UploadFile
from fastapi.dependencies.utils import (
    multipart_incorrect_install_error,
    multipart_not_installed_error,
)


def test_incorrect_multipart_installed_form(monkeypatch):
    monkeypatch.delattr("multipart.multipart.parse_options_header", raising=False)
    with pytest.raises(RuntimeError, match=multipart_incorrect_install_error):
        app = FastAPI()

        @app.post("/")

from typing import Annotated

from fastapi import FastAPI, File, UploadFile

app = FastAPI()


@app.post("/files/")
async def create_file(file: Annotated[bytes | None, File()] = None):
    if not file:
        return {"message": "No file sent"}
    else:
        return {"file_size": len(file)}


@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile | None = None):
    if not file:

    app = FastAPI()

    testing_file_store: List[UploadFile] = []

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

    client = TestClient(app)
    with path.open("rb") as file:
        response = client.post("/uploadfile/", files={"file": file})
    assert response.status_code == 200, response.text

    response = client.post("/files/")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "No file sent"}


def test_post_uploadfile_no_body():
    response = client.post("/uploadfile/")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "No upload file sent"}


def test_post_file(tmp_path):
    path = tmp_path / "test.txt"

from fastapi import FastAPI, File, UploadFile
from fastapi.responses import HTMLResponse

app = FastAPI()


@app.post("/files/")
async def create_files(
    files: list[bytes] = File(description="Multiple files as bytes"),
):
    return {"file_sizes": [len(file) for file in files]}


@app.post("/uploadfiles/")
async def create_upload_files(
    files: list[UploadFile] = File(description="Multiple files as UploadFile"),
):

文件作为「表单数据」上传。

如果把*路径操作函数*参数的类型声明为 `bytes`，**FastAPI** 将以 `bytes` 形式读取和接收文件内容。

这种方式把文件的所有内容都存储在内存里，适用于小型文件。

不过，很多情况下，`UploadFile` 更好用。

## 含 `UploadFile` 的文件参数

定义文件参数时使用 `UploadFile`：

```Python hl_lines="12"
{!../../../docs_src/request_files/tutorial001.py!}
```

`UploadFile` 与 `bytes` 相比有更多优势：

* 使用 `spooled` 文件：
    * 存储在内存的文件超出最大上限时，FastAPI 会把文件存入磁盘；
* 这种方式更适于处理图像、视频、二进制文件等大型文件，好处是不会占用所有内存；

    # For coverage
    # TODO: in theory this would allow declaring types that could be lists of UploadFile
    # and other types, but I'm not even sure it's a good idea to support it as a first
    # class "feature"

from fastapi import FastAPI, File, UploadFile

app = FastAPI()


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


@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile):