Add focus, onFocus, onBlur to SearchBar (#3417)

[chaotic-dev]

Description

Added focus method and the onFocus and onBlur events to the SearchBar control based on those from the TextField control

Fixes #3417

Test Code

# Test code for the review of this PR
import flet as ft

def main(page: ft.Page):
    page.horizontal_alignment = ft.CrossAxisAlignment.CENTER

    def close_anchor(e):
        text = f"Color {e.control.data}"
        anchor.value = text
        anchor.focus()
        anchor.update()
        # print(f"closing view from {text}")
        # anchor.close_view(text)

    anchor = ft.SearchBar(
        view_elevation=4,
        divider_color=ft.colors.AMBER,
        bar_hint_text="Search colors...",
        view_hint_text="Choose a color from the suggestions...",
        controls=[
            ft.ListTile(title=ft.Text(f"Color {i}"), on_click=close_anchor, data=i)
            for i in range(10)
        ],
    )

    page.add(
        ft.Row(
            alignment=ft.MainAxisAlignment.CENTER,
            controls=[
                ft.OutlinedButton(
                    "Open Search View",
                    on_click=lambda _: anchor.open_view(),
                ),
            ],
        ),
        anchor,
    )


ft.app(main)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• I signed the CLA.
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings

• New and existing tests pass locally with my changes
• I have made corresponding changes to the documentation (if applicable)

Screenshots (if applicable):

Additional details

Summary by Sourcery

This pull request adds new functionality to the SearchBar control by introducing a focus method and onFocus and onBlur events. These changes enhance the interactivity and usability of the SearchBar component.

• New Features:
  • Added focus method to the SearchBar control.
  • Introduced onFocus and onBlur events to the SearchBar control.

[CLAassistant]

All committers have signed the CLA.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request introduces focus management to the SearchBar control by adding a focus method and onFocus and onBlur event handlers. The changes include updates to the Python and Dart codebases to support these new features, ensuring that the SearchBar can now handle focus events and trigger corresponding actions.

File-Level Changes

Files	Changes
sdk/python/packages/flet-core/src/flet_core/search_bar.py packages/flet/lib/src/controls/search_anchor.dart	Added focus management and event handling (onFocus, onBlur) to the SearchBar control.

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[sourcery-ai]

Hey @chaotic-dev - I've reviewed your changes - here's some feedback:

Overall Comments:

• Consider adding brief documentation for the new focus-related methods and properties in the Python code to help users understand how to use these new capabilities.

Here's what I looked at during the review

• 🟡 General issues: 3 issues found
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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[sourcery-ai]

suggestion (bug_risk): Use a more unique identifier for focus events

Using the current time as an identifier could potentially lead to issues if multiple focus events occur within the same second. Consider using a more unique identifier, such as a UUID or a monotonically increasing counter.

Suggested change

	self._set_attr_json("focus", str(time.time()))
	import uuid
	self._set_attr_json("focus", str(uuid.uuid4()))

[sourcery-ai]

question: Unused state variable _focused

The _focused state variable is set but never used in the current implementation. Is it intended for future use, or can it be removed to keep the code clean?

[sourcery-ai]

suggestion: Consider adding error handling for focus/blur events

While focus/blur operations are unlikely to fail, it's good practice to handle potential errors. Consider adding try-catch blocks or at least documenting any possible exceptions that might occur during these operations.

Suggested change

	widget.backend.triggerControlEvent(
	try {
	widget.backend.triggerControlEvent(
	} catch (e) {
	// Handle the error or log it
	}