Fix unexpected behavior on TextField showing error when errorText is empty

[andersou]

Description

When the page is refreshed, the input field is incorrectly marked as an error if errorText is set previosly. This happens because _set_attr_internal prevents the errorText attribute from being set to None, resulting in it being set as an empty string, which causes the error border to appear.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• [x ] I signed the CLA.
• [ x] My code follows the style guidelines of this project
• [ x] I have performed a self-review of my own code
• [x ] I have commented my code, particularly in hard-to-understand areas
• [ x] My changes generate no new warnings
• [x ] New and existing tests pass locally with my changes
• [ x] I have made corresponding changes to the documentation (if applicable)

Screenshots (if applicable):

after page refresh:

Summary by Sourcery

Fix the input field error display issue by setting errorText to null when it is empty, preventing unnecessary error borders.

Bug Fixes:

• Fix the issue where an input field is incorrectly marked as an error when the errorText is empty by ensuring the errorText attribute is set to null instead of an empty string.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request fixes a bug in the input field error display. The main change is in the buildInputDecoration function, where the errorText property is now set to null when it's an empty string, preventing the error border from appearing unnecessarily after a page refresh.

File-Level Changes

Change	Details	Files
Modified error text handling in input field decoration	Changed errorText assignment to use a ternary operator Set errorText to null when the attribute string is empty Maintained original behavior when errorText is not empty	packages/flet/lib/src/utils/form_field.dart

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[sourcery-ai]

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

Overall Comments:

• Consider adding a unit test to verify this behavior and prevent future regressions.
• It might be helpful to add a brief comment explaining the rationale behind this change for future maintainers.

Here's what I looked at during the review

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

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[FeodorFitsner]

Could you include a simple repro code/app to validate the fix?

[andersou]

@FeodorFitsner

import flet as ft

import logging

logging.basicConfig(level=logging.DEBUG)


def main(page: ft.Page):
    txt = ft.TextField(label="Endereço de IP")

    def validate(e):
        if not txt.value:
            txt.error_text = "Campo obrigatório"
        else:
            txt.error_text = None
        txt.update()

    btn = ft.ElevatedButton("Enviar", on_click=validate)
    page.add(txt)
    page.add(btn)


ft.app(target=main)

run the app with flet run --web
click in the button, the validation will appears
insert any text in the textfield, and click the button, error text will disappear
when refresh this page, the inputtext will have an error border