send_file calls max_age with Path instead of str

[tunetheweb]

We use the following code to override the SEND_FILE_MAX_AGE_DEFAULT for certain file types:

# Set WOFF and WOFF2 caching to return 1 year as they should never change
class MyServer(Flask):
    def get_send_file_max_age(self, name):
        if name.lower().endswith('.woff') or name.lower().endswith('.woff2'):
            return 31536000
        return Flask.get_send_file_max_age(self, name)


# Initialize The Server
app = MyServer(__name__, template_folder=TEMPLATES_DIR, static_folder=STATIC_DIR)

As of the newly released Flask 2.0 this is failing with the following error:

  File "/Users/barry/almanac.httparchive.org/src/server/__init__.py", line 19, in get_send_file_max_age
    if filename.lower().endswith('.woff') or filename.lower().endswith('.woff2'):
AttributeError: 'PosixPath' object has no attribute 'lower'

So we have to change this to this to convert the name to a string:

# Set WOFF and WOFF2 caching to return 1 year as they should never change
class MyServer(Flask):
    def get_send_file_max_age(self, name):
        if str(name).lower().endswith('.woff') or str(name).lower().endswith('.woff2'):
            return 31536000
        return Flask.get_send_file_max_age(self, name)


# Initialize The Server
app = MyServer(__name__, template_folder=TEMPLATES_DIR, static_folder=STATIC_DIR)

Is this an intended behaviour change as the documentation still says this uses a string as an argument rather than a PosixPath?

Environment:

• Python version: 3.8
• Flask version: 2.0

[davidism]

You'll need to call name = os.fspath(name) first if your code only expects to be working with strings and not Path objects.

[tunetheweb]

Then should the documentation be updated to note it's now a Path object and not a string: https://flask.palletsprojects.com/en/2.0.x/api/#flask.Flask.get_send_file_max_age

Parameters: filename (str) –

[davidism]

Note that your implementation already has an issue, as get_send_file_max_age could be called with None when sending file objects instead of paths. I'll change send_file to always pass a string or None, and update the annotations too.

[tunetheweb]

Good spot on the None issue. Will update my code.

BTW I was happy to leave as Path but just wanted to check it was an intentional change. Then again I'm probably not the only one who will experience this as that code snippet is all over Stack Overflow (think that's where I got it from!) so maybe best to revert as you say.

Thanks for the quick response btw!