CODEWITHSUNDEEP
pythonlinuxflask
joe
joe

Reputation: 729

Serving changing files with Flask

I currently am using Flask to serve up a visual programming environment. I would like the users to be able to load the code currently in the system if they come back later. I have tried using:

return redirect(url_for('static', filename='rawxml.txt'))
return redirect(send_from_directory('static', 'rawxml.txt'))

However, both will never serve the modified version of the file, and instead what seems to be a cached version of the file. How can I serve a file that gets rewritten often with the new content.

Note: rawxml.txt is stored in the "static" directory, but it is a sym link to where the actual XML is (I have tried a hard link as well).

Upvotes: 4

Views: 1601

Answers (2)

Paulo Scardine
Paulo Scardine

Reputation: 77349

Untested:

url = url_for('static', filename='rawxml.txt', t=time.time())
return redirect(url)

If the content is not that dynamic, you can rewrite it to use an MD5 hash of the file - this way you will only invalidate the cache when the file changes. The answer from tbicr looks like a good example of this.

[update]

At the jQuery side, do something like:

$('#some_selector').load('{{ url }}#'+new Date().valueOf());

Upvotes: 1

tbicr
tbicr

Reputation: 26080

I have next implementation for static files:

hash_cache = {}

@app.url_defaults
def add_hash_for_static_files(endpoint, values):
    '''Add content hash argument for url to make url unique.
    It's have sense for updates to avoid caches.
    '''
    if endpoint != 'static':
        return
    filename = values['filename']
    if filename in hash_cache:
        values['hash'] = hash_cache[filename]
        return
    filepath = safe_join(app.static_folder, filename)
    if os.path.isfile(filepath):
        with open(filepath, 'rb') as static_file:
            filehash = get_hash(static_file.read(), 8)
            values['hash'] = hash_cache[filename] = filehash

It just add hash argument to urls which generated with url_for.

Upvotes: 5

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