Solving CSS Cache Problems in FLASK web framework on Windows Platform

css_cache_buster_original.py

'''
flask.org suggests to use snipets of cache buster as below
http://flask.pocoo.org/snippets/40/
'''

@app.context_processor
def override_url_for():
    return dict(url_for=dated_url_for)

def dated_url_for(endpoint, **values):
    if endpoint == 'static':
        filename = values.get('filename', None)
        if filename:
            file_path = os.path.join(app.root_path,
                                     endpoint, filename)
            values['q'] = int(os.stat(file_path).st_mtime)
    return url_for(endpoint, **values)
  
  '''
  but problem happens line 16 --> os.stat(file_path).st_mtime
  it returns wrong file_path mixed with '/' and '\' like this and causing problem
  ....Flask\static\css/flask.css?q=1280549780 
  '''

css_caching01_windows.py

'''
while HTML has CSS ref as below.
funtion gives override on path+filename like, css/flask.css?q=7831243, the numbers were randomly given.
  <link rel="stylesheet" href="{{ url_for('static', filename='css/flask.css') }}">
'''
import os, random

@app.context_processor
def override_url_for():
    # app.logger.debug(dict(url_for=dated_url_for))
    return dict(url_for=dated_url_for)

def dated_url_for(endpoint, **values):           # double stars = dict_type
    if endpoint == 'static' :
        filename = values.get('filename', None)  # None = default values if it's missing.
        if filename and filename[0:3] == 'css':
            file_path = os.path.join(app.root_path, endpoint, filename)
            values['q'] = int(random.randint(0,10000000))
    app.logger.debug(values)
    return url_for(endpoint, **values)
  

sof_solution_qna.py

'''
Stackoverflow Q&A saids Error's a matter of flatform,windows
https://stackoverflow.com/questions/237079/how-to-get-file-creation-modification-date-times-in-python
'''

import os
import platform

def creation_date(path_to_file):
    """
    Try to get the date that a file was created, falling back to when it was
    last modified if that isn't possible.
    See http://stackoverflow.com/a/39501288/1709587 for explanation.
    """
    if platform.system() == 'Windows':
        return os.path.getctime(path_to_file)
    else:
        stat = os.stat(path_to_file)
        try:
            return stat.st_birthtime
        except AttributeError:
            # We're probably on Linux. No easy way to get creation dates here,
            # so we'll settle for when its content was last modified.
            return stat.st_mtime

Logging would be...

--------------------------------------------------------------------------------
DEBUG in flask_app [flask_app.py:19]:
{'filename': 'css/flask.css', 'q': 668776}
--------------------------------------------------------------------------------
127.0.0.1 - - [28/Jun/2017 15:31:59] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [28/Jun/2017 15:31:59] "GET /css/flask.css?q=668776 HTTP/1.1" 200 -
127.0.0.1 - - [28/Jun/2017 15:32:00] "GET /imgs/0_angry_tig.jpg HTTP/1.1" 200 -