我们可以在上传python-flask之前计算上传文件的大小吗 [英] can we count the upload filesize before uploading in python-flask

问题描述

我有一个简单的flask应用程序，其中我正在上传单个文件，但文件大小小于5MB
为此，我在flask-app中定义了
if request.content_length < 5.250e+6: ## setting upload limit to 5MB测试用例；但这是在上传后验证文件大小；还是我错了.
所以有什么方法可以在上传之前获取文件大小?

I have a simple flask app where i am uploading single file but with file size of less than 5MB
for that i have defined
if request.content_length < 5.250e+6: ## setting upload limit to 5MB test case in my flask-app; but this is verifying the file size after uploading it; or may be i am wrong.
so is there any way to get the file size before uploading it???

这是python 解决方案 + GAE，但我是python网络框架的新手；我对flask
知之甚少，而该解决方案是基于webapp2的，这对我和GAE来说都很复杂；那是另一个故事. 因此任何人都可以在flask中生成等效的flask或任何其他可能的方式?

Here is python solution on python+GAE, but i am new to python web framework; i know very little in flask
and this solution is based on webapp2 which is very complicated for me and also its on GAE; that is another story. so can anyone generate its flask equivalent or any other possible way to do it in flask???

推荐答案

这是AudriusKažukauskas答案的扩展版本:

This is a bit expanded version of Audrius Kažukauskas's answer:

所以有什么方法可以在上传之前获取文件大小?

so is there any way to get the file size before uploading it???

否. 根据 werkzeug的文档处理上传的文件，您不能在所有浏览器不能保证上传之前验证内容大小.仅保证request中所有数据的总内容长度在此.网络浏览器.因此，Flask/werkzeug只能在文件上传后强制执行检查.

No. As per werkzeug's documentation that Flask use to handle uploaded file, you cannot verify the content-size before uploading is NOT guaranteed by all browsers. Only the total content-length of all the data in the request is guaranteed to be there. web-browsers. Hence, Flask/werkzeug can enforce checking only after file-upload.

但是，为避免Web服务器因内存溢出而崩溃，可以并且应该限制可上传的大小.这是配置变量MAX_CONTENT_LENGTH，您可以在应用程序的配置文件中提及.

However, to avoid crashing of your web-server from memory-overflow, you can and should limit the upload-able size. Here comes the config variable MAX_CONTENT_LENGTHwhich you can mention in app's config file.

Flask doc :

from flask import Flask, Request

app = Flask(__name__)
app.config['MAX_CONTENT_LENGTH'] = 16 * 1024 * 1024  # for 16MB max-limit.

但是，对于任何严肃的应用程序，您应该考虑使用Flask-plugin Flask-Uploads 允许使用更高级的选项，例如将某些文件类型列入白名单和黑名单，基于类型的上传规则，可配置的上传目标等.

However, for any serious application, you should consider using the Flask-plugin Flask-Uploads which allows more advanced options such as white-listing and black-listing certain file-types, type-based upload rules, configurable upload destinations etc.

您可以提问 为什么我应该寻求额外的扩展 .
因为Flask是一个微框架.不是万能的框架.

You can question why should i go for the extra extension.
Because, Flask is a micro-framework. Not a do-it-all framework.

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