60 lines
2.2 KiB
Python
60 lines
2.2 KiB
Python
# Inspired by https://github.com/ChrisTM/Flask-CacheBust
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# Uses query strings so CSS font files are found without having to resort to absolute URLs
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import hashlib
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import os
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def init_cache_busting(app):
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"""
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Configure `app` to so that `url_for` adds a unique query string to URLs generated
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for the `'static'` endpoint.
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This allows setting long cache expiration values on static resources
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because whenever the resource changes, so does its URL.
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"""
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static_folder = os.path.join(app.static_folder, '') # path to the static file folder, with trailing slash
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hash_table = {} # map of file hashes
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app.logger.debug('Computing cache-busting values...')
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# compute file hashes
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for dirpath, __, filenames in os.walk(static_folder):
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for filename in filenames:
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# compute version component
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rooted_filename = os.path.join(dirpath, filename)
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with open(rooted_filename, 'rb') as f:
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file_hash = hashlib.md5(f.read()).hexdigest()[:7]
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# save version to tables
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file_path = rooted_filename.replace(static_folder, "")
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file_path = file_path.replace("\\", "/") # Convert Windows path to web path
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hash_table[file_path] = file_hash
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app.logger.debug('Finished computing cache-busting values')
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def bust_filename(filename):
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return hash_table.get(filename, "")
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def unbust_filename(filename):
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return filename.split("?", 1)[0]
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@app.url_defaults
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def reverse_to_cache_busted_url(endpoint, values):
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"""
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Make `url_for` produce busted filenames when using the 'static' endpoint.
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"""
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if endpoint == "static":
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file_hash = bust_filename(values["filename"])
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if file_hash:
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values["q"] = file_hash
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def debusting_static_view(filename):
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"""
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Serve a request for a static file having a busted name.
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"""
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return original_static_view(filename=unbust_filename(filename))
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# Replace the default static file view with our debusting view.
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original_static_view = app.view_functions["static"]
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app.view_functions["static"] = debusting_static_view
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