将文件上传到 Flask 时出现 Bad Request 400答案

【问题标题】：Bad Request 400 when uploading file to Flask将文件上传到 Flask 时出现 Bad Request 400
【发布时间】：2022-11-29 23:47:53
【问题描述】：

我有一个如下所示的 Flask 服务器：

import flask, os, werkzeug.utils

UPLOAD_FOLDER = "files/"
ALLOWED_EXTENSIONS = {"txt"}

def isFileAllowed(file):
    return str("." in file and file.rsplit(".", 1)[1].lower() in ALLOWED_EXTENSIONS)

app = flask.Flask(__name__)
app.config["UPLOAD_DIR"] = UPLOAD_FOLDER

@app.route("/log_receiver", methods = ["POST", "GET"])
def log_receiver():
    if flask.request.method == "POST":
        file = flask.request.files["file"]
        if file and isFileAllowed(file):
            filename = werkzeug.utils.secure_filename(file)
            file.save(os.path.join(app.config["UPLOAD_DIR"], filename))
            return "Sucessfully uploaded"
        return "File couldn't be uploaded"            
    return "404, not found"
        

if __name__ == '__main__':
    app.run()

我做了一个测试上传器，也是用 Python 编写的，它看起来像这样：

import requests

def log_uploader():
    with open("log.txt", "rb") as log:
        r = requests.post("http://localhost:5000/log_receiver", files={"log.txt": log})
        print(r.text)

if __name__ == '__main__':
    log_uploader()

问题是，每当我运行它时，都会收到 404 错误。

我尝试删除flask.request.files 中的 ["file"]，这会删除 400 错误，但会带来 500 错误并显示以下日志：

[2022-11-29 16:05:46,547] ERROR in app: Exception on /log_receiver [POST]
Traceback (most recent call last):
  File "/home/day/.local/lib/python3.9/site-packages/flask/app.py", line 2525, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/day/.local/lib/python3.9/site-packages/flask/app.py", line 1822, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/day/.local/lib/python3.9/site-packages/flask/app.py", line 1820, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/day/.local/lib/python3.9/site-packages/flask/app.py", line 1796, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args)
  File "/home/day/Desktop/Coding/Quickraft/Server-side/APIs/main.py", line 17, in log_receiver
    filename = werkzeug.utils.secure_filename(file)
  File "/home/day/.local/lib/python3.9/site-packages/werkzeug/utils.py", line 221, in secure_filename
    filename = unicodedata.normalize("NFKD", filename)
TypeError: normalize() argument 2 must be str, not ImmutableMultiDict
127.0.0.1 - - [29/Nov/2022 16:05:46] "POST /log_receiver HTTP/1.1" 500 -

我该如何解决这个问题？提前致谢，
戴蒙斯。

【问题讨论】：

标签： python file flask

【解决方案1】：

再次看到烧瓶documentationrequest.files

files 中的每个值都是一个 Werkzeug FileStorage 对象

它不仅仅是文件名，还远不止于此。错误消息告诉您一些事情：secure_filename() 需要一个字符串，但您向它传递的不是字符串。

再次查看文件上传的烧瓶文档：https://flask.palletsprojects.com/en/2.2.x/patterns/fileuploads/

【讨论】：

谢谢！它按预期工作，我现在可以上传文件了。