Скачать или смотреть How to Fix Python FileHandler Not Logging info Messages

Learn how to resolve the issue of a Python `FileHandler` failing to log `info` messages by adjusting the logger's configuration.
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This video is based on the question https://stackoverflow.com/q/67928976/ asked by the user 'Gopi' ( https://stackoverflow.com/u/16191897/ ) and on the answer https://stackoverflow.com/a/67929046/ provided by the user 'Sven Eberth' ( https://stackoverflow.com/u/3749896/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Problem: Python FileHandler Not Logging INFO Messages

If you're working with logging in Python and you've stumbled upon a situation where your FileHandler doesn't seem to record logger.info messages, you're not alone. This is a common issue that can leave developers scratching their heads, especially when they notice that other logging levels, such as log.error, work just fine. In this guide, we’ll identify the cause of the problem and provide a clear solution to get your logging back on track.

The Scenario

Consider this common setup for logging in Python. You initialize formatters, file handlers, and stream handlers and add them to your logger as follows:

[[See Video to Reveal this Text or Code Snippet]]

When executing this code, you may notice that while the log.error messages are correctly written to your log file, the log.info messages are mysteriously absent.

What’s Going Wrong?

The issue lies in the configuration of the logger itself. While you've correctly set the logging level for both the FileHandler and StreamHandler, you still need to set the level for the main logger (log in this case). If you do not specify a logging level for your logger, it defaults to WARNING, which means it won’t capture INFO messages.

The Solution: Setting the Logger Level

Here's how to resolve this problem:

Step 1: Set the Logger's Level

Add the following line to your code to set the logger's level to DEBUG:

[[See Video to Reveal this Text or Code Snippet]]

This ensures that all messages at the DEBUG level and above (including INFO, WARNING, ERROR, and CRITICAL) will be logged. Your updated code will look like this:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Test Your Logging

Run your code again, and this time you should see INFO messages being written to both your console output and the invokeRestApi.log file.

Conclusion

By setting the logging level for your logger to DEBUG, you can successfully log all messages you wish to capture, including info messages. This simple adjustment can make a big difference in effectively monitoring your application’s behavior and troubleshooting issues.

Don’t underestimate the importance of configuring your logging setup properly; it’s a small step that can lead to significant improvements in how you manage information about your application's operation. Happy coding!