如何限制Python Fastapi Post请求上传文件大小？

Question

我正在创建一个fastapi python应用程序，其中用户上传要处理的文件。我不希望该文件超过大小x（在字节中）。

在邮政请求将文件存储在内存中之前，如何限制文件上传大小？

我正在使用Uivcorn进行测试，但我希望可以使用Google Cloud Platform（GCP）部署此代码。我不确定是否可以在Python代码端或服务器配置侧进行此操作。

代码段：

from fastapi import (
     FastAPI, 
     Path, 
     File, 
     UploadFile, 
) 

app = FastAPI()

@app.post("/")
async def root(file: UploadFile  = File(...)):
     text = await file.read()
     text = text.decode("utf-8")
     return len(text)

Answer 1

我找到了一个Python库，可以通过Fastapi中间件来照顾这一点。如果上传文件太大，它将抛出413 HTTP错误； “错误：请求实体太大”

from starlette_validation_uploadfile import ValidateUploadFileMiddleware

 from fastapi import (
      FastAPI, 
      Path, 
      File, 
      UploadFile, 
 ) 


app = FastAPI()

#add this after FastAPI app is declared 
app.add_middleware(
        ValidateUploadFileMiddleware,
        app_path="/",
        max_size=1048576, #1Mbyte
        file_type=["text/plain"]
)


 @app.post("/")
 async def root(file: UploadFile  = File(...)):
      #...do something with the file
      return {"status: upload successful"}

Answer 2

它通常通过Web服务器（例如Nginx或Apache）控制，但是如果要在服务器端控制，则可以使用此代码：

from fastapi import (
    FastAPI,
    Path,
    File,
    UploadFile,
)

app = FastAPI()

@app.post("/")
async def root(file: UploadFile = File(...)):
    if len(await file.read()) >= 8388608:
        return {"Your file is more than 8MB"}

Answer 3

您可以使用中间件。我使用了此一个，它的用法很不错

（我更改了原始代码a位）：

middleware.py：

from typing import Optional
from fastapi import HTTPException

class ContentSizeLimitMiddleware:
    """Content size limiting middleware for ASGI applications

    Args:
      app (ASGI application): ASGI application
      max_content_size (optional): the maximum content size allowed in bytes, None for no limit
    """

    def __init__(
        self,
        app,
        max_content_size: Optional[int] = None,
    ):
        self.app = app
        self.max_content_size = max_content_size

    def receive_wrapper(self, receive):
        received = 0

        async def inner():
            nonlocal received
            message = await receive()
            if message["type"] != "http.request" or self.max_content_size is None:
                return message
            body_len = len(message.get("body", b""))
            received += body_len

            if received > self.max_content_size:
                raise HTTPException(detail="File is too big", status_code=413)

            return message

        return inner

    async def __call__(self, scope, receive, send) -> None:
        if scope["type"] != "http":
            await self.app(scope, receive, send)
            return

        wrapper = self.receive_wrapper(receive)
        await self.app(scope, wrapper, send)

main.py：

app.add_middleware(ContentSizeLimitMiddleware, max_content_size=5 * 1024 * 1024) # 5MB

此解决方案仅读取文件的必要部分，并拒绝请求

以此starlette视图为例：

@app.route("/documents/upload", methods=["POST"])
def upload_document(request):
    data = await request.body()
    if len(data) > Config.MAX_FILE_SIZE:
        return api_400(
            f"This file exceeds the maximum file size we support at this time ({Config.MAX_FILE_SIZE})",
            code=MAX_FILE_SIZE_EXCEEDED,
        )
    ...

如果最大文件大小为5MB，并且上传的文件为50MB，则此实现在拒绝请求之前，将整个50MB读取到内存中。

Answer 4

我正在使用fastapi。我在端点中用用过uploadfile。

@app.route("/documents/upload")
def upload_document(file: UploadFile = File(...),
    custom_fields_mapping: str = Form(None)):
    try:
        if file.size > 500*1024: 
           return {"success": True, "message": "BOD processing started in the background."}