fix: Display informative message when date has wrong format

[ndonkoHenri]

Description

Closes #4017

Summary by Sourcery

Improve date and time picker components by adding validation for date values and refactoring attribute handling to enhance code clarity and robustness.

Bug Fixes:

• Add validation to ensure date values are of type date, datetime, or None, raising a ValueError if not.

Enhancements:

• Refactor date and time picker components to improve attribute handling and validation.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request improves the handling of date and time inputs in the Flet library. It introduces a new utility function for datetime conversion and validation, updates the DatePicker and CupertinoDatePicker classes to use this function, and adds error handling for datetime parsing in the Control class.

File-Level Changes

Change	Details	Files
Introduce new utility function for datetime conversion and validation	Add new file with datetime_to_string function Implement has_valid_datetime_format function to check string format Add assertion to ensure valid datetime format	sdk/python/packages/flet-core/src/flet_core/utils/datetime.py
Update DatePicker class to use new datetime utility function	Modify init method to accept Union[datetime, str] for date-related parameters Replace inline datetime conversion with calls to datetime_to_string function Update type hints for setter methods	sdk/python/packages/flet-core/src/flet_core/date_picker.py
Update CupertinoDatePicker class to use new datetime utility function	Modify init method to accept Union[datetime, str] for date-related parameters Replace inline datetime conversion with calls to datetime_to_string function Update type hints for setter methods	sdk/python/packages/flet-core/src/flet_core/cupertino_date_picker.py
Add error handling for datetime parsing in Control class	Wrap DateTime.parse call in a try-except block Return null if parsing fails instead of throwing an exception	packages/flet/lib/src/models/control.dart
Minor refactoring in TimePicker class	Move comment about value_string format to a more appropriate location	sdk/python/packages/flet-core/src/flet_core/time_picker.py

---

Tips

• Trigger a new Sourcery review by commenting @sourcery-ai review on the pull request.
• Continue your discussion with Sourcery by replying directly to review comments.
• You can change your review settings at any time by accessing your dashboard:
  • Enable or disable the Sourcery-generated pull request summary or reviewer's guide;
  • Change the review language;
• You can always contact us if you have any questions or feedback.

[sourcery-ai]

Hey @ndonkoHenri - I've reviewed your changes and they look great!

Here's what I looked at during the review

• 🟡 General issues: 1 issue found
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook

_{Help me be more useful! Please click 👍 or 👎 on each comment to tell me if it was helpful.}