feat: add formFieldKey and improve validation

[manonfiZ]

Description

This PR adds real-time validation support to OnscreenKeyboardTextFormField by introducing a new formFieldKey property. This enhancement allows developers to access the form field state and implement real-time validation more effectively.

Key changes:

• Added formFieldKey parameter to OnscreenKeyboardTextFormField
• Implemented real-time validation in the example app
• Added comprehensive test coverage for the new functionality

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

How Has This Been Tested?

The changes have been verified through the following tests:

• Added test case for real-time validation using formFieldKey
• Verified validation state changes on text input
• Tested both valid and invalid input scenarios

Test Configuration:

• Package Version: 0.4.0+1
• Flutter SDK: 3.35.4
• Operating System: Linux Mint 22.2

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[albinpk]

Thanks for the PR! 🙌

I see you’re trying to validate using FormFieldState. You can achieve the same behavior by wrapping the field in a Form widget and using the form’s key to call validate() or save() for all fields. Could you confirm if that works for your use case?

[manonfiZ]

Yes it works @albinpk

The thing in my case is that I have to refactor all my entire codebase and wrap all FormField by a Form. ​😅​
I had a custom formfield on top of the flutter formfield. That what was there and to use the feature provided by your package, i have just replaced the flutter form field and then use OnscreenKeyboardTextFormField, in my custom widget.

And then the problem is that every this custom widget was used and and had a validation based on FormFieldState start crying cause this one is null.

In addition to my concern, i think it will be useful to validate single TextFormField without having to wrap with a form.

[albinpk]

Thanks for explaining your use case. I’ll merge the PR.