What we should do when the file gets so long - flutter

Question

when I'm done with a page I can extract widget as I can for more readable, But this makes the file longer, So I find a solution I can use "part and part of " I can take extract widgets inside part of (E.g login_view_part.dart), this solves the problem, But I have read opinions about the non-use/bad-use of part and part of.
1- this is a good solution for problems like this? If not what should we
do?
2- we should use part and part of? anywhere. (except code generation)
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:second_hand/core/constants/navigation/navigation_constants.dart';
import 'package:second_hand/core/extensions/context_extension.dart';
import 'package:second_hand/core/init/navigation/navigation_service.dart';
import 'package:second_hand/core/init/notifier/product_notifer.dart';
import 'package:second_hand/view/_product/_widgets/textformfield/custom_text_form_field.dart';
import 'package:second_hand/view/app/addproduct/include_some_details/viewmodel/include_some_details_view_model.dart';
enum ProductState {
verybad(name: 'Very Bad'),
bad(name: 'Bad'),
normal(name: 'Normal'),
good(name: 'Good'),
verygood(name: 'Very Good');
const ProductState({required this.name});
final String name;
}
class IncludeSomeDetailsView extends StatefulWidget {
const IncludeSomeDetailsView({super.key});
#override
State<IncludeSomeDetailsView> createState() => IncludeSomeDetailsViewState();
}
class IncludeSomeDetailsViewState extends IncludeSomeDetailsViewModel {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Include some details'),
),
body: Form(
key: formKey,
child: Padding(
padding: context.paddingAllMedium,
child: Column(
children: [
TitleTextFormField(titleController: titleController),
DescriptionTextFormField(describeController: describeController),
DropdownButton<ProductState>(
value: valueProductState,
items: ProductState.values
.map<DropdownMenuItem<ProductState>>(
(value) => DropdownMenuItem<ProductState>(
value: value,
child: Text(value.name),
),
)
.toList(),
onChanged: (productState) {
setState(
() {
stateController.text = productState!.name;
valueProductState = productState;
},
);
},
),
const Spacer(),
NextButton(
formKey: formKey,
titleController: titleController,
stateController: stateController,
describeController: describeController),
],
),
),
),
);
}
}
class TitleTextFormField extends StatelessWidget {
const TitleTextFormField({
Key? key,
required this.titleController,
}) : super(key: key);
final TextEditingController titleController;
#override
Widget build(BuildContext context) {
return Padding(
padding: context.paddingOnlyTopSmall,
child: CustomTextFormField(
controller: titleController,
labelText: 'title',
prefix: const Icon(Icons.title_outlined),
),
);
}
}
class DescriptionTextFormField extends StatelessWidget {
const DescriptionTextFormField({
Key? key,
required this.describeController,
}) : super(key: key);
final TextEditingController describeController;
#override
Widget build(BuildContext context) {
return Padding(
padding: context.paddingOnlyTopSmall,
child: CustomTextFormField(
controller: describeController,
labelText: 'description',
prefix: const Icon(Icons.description),
),
);
}
}
class NextButton extends StatelessWidget {
const NextButton({
Key? key,
required this.formKey,
required this.titleController,
required this.stateController,
required this.describeController,
}) : super(key: key);
final GlobalKey<FormState> formKey;
final TextEditingController titleController;
final TextEditingController stateController;
final TextEditingController describeController;
#override
Widget build(BuildContext context) {
return ElevatedButton(
onPressed: () {
if (formKey.currentState!.validate()) {
context.read<ProductNotifier>().setProduct(
title: titleController.text,
state: stateController.text,
description: describeController.text,
);
NavigationService.instance.navigateToPage(path: NavigationConstants.UPLOAD_PHOTOS);
}
},
child: const Text(
'Next',
),
);
}
}