Bug Fixes and Enhancements: Rating Validation, Duplicate Check, and Error Messages

[laurabuenemann]

Hello Pybrary Team,

Great job on this project :) It looks very professional and well-structured with short methods and even a logo!
I find the feature allowing books to be sorted by column headers in the Tkinter table very practical.

I have a few suggestions for improvement:

1. Rating Validation:

• Issue: The README specifies ratings between 1 and 5, but currently, any number can be entered, including negatives and excessively high values.
• Suggestion: Restrict the rating input to integers between 1 and 5 to maintain consistency.

2. Duplicate Entry Check:

• Issue: Duplicate books with identical details can be added.
• Suggestion: Implement a check to prevent duplicate entries and display an alert message if a duplicate is detected. Of course, you may not want to prevent duplicates if the library is used by several people.

3. User-Friendly Error Messages:

• Issue: Error messages for invalid entries are "only" printed in the terminal.
• Suggestion: Display these error messages in a Toplevel window to make them immediately visible to the user.

Good luck with the completion of your project.