flex_form 0.0.1

Flex Form streamlines development forms of all complexities.

Overview

Form development typically involves duplication of code at many levels from managing user interactions with a form to handling the loading and submission of the form's data. And depending on the complexity of a form and the number of forms required by an application, the effort to develop and maintain the forms can grow quickly.

This is why FlexForm was born, and it attempts to achieve these goals:

1. ❌ Consolidating all essential form interaction logic and making it available for free to developers.
2. ❌ Streamlining the development of forms by making it highly configurable and extensible.
3. ❌ Supporting all types of form inputs while leaving it up to developers to provide the UI for their forms.
4. ❌ Enabling extension of form's custom validation while providing APIs and hooks for better control of form custom functionalities.

Features

1. ❌ Flexibility - FlexForm supports form development with all popular input types including text, single-select, multi-select and toggle.
2. ❌ Configurable - FlexForm provides field configurations which can be used to configure how form fields function during runtime. E.g. allowEmpty, minChars, maxChars, regexList, etc.
3. ❌ Extensible - FlexForm enables forms with any level of complexity from a simple Login form to forms with any number of fields.
4. ❌ Customization - FlexForm enables easy and flexible integration of custom validation logic based on a form's business domain requirements.
5. ❌ UI-independent - FlexForm does not dictate how forms should look and feel. Instead, it takes care all of the basic form input interaction and provides update of the form's state which be used by application at runtime to build for form.
6. ❌ Modular - FlexForm's architecture enables developers to build form components that provide specific functionalities for the form based on the application's domain requirements. These components can be developed and tested independently of FlexForm.

Getting started

FlexForm's architecture is based on the BLoC design pattern. Specifically, FlexForm depends on bloc and flutter_bloc, which are very popular packages that implement BLoC and which provides a very good state management solution for Flutter applications.

FlexForm supports all platforms and there's no additional setup required to get started.

To get started, simply add a dependency to flex_form in your Flutter application's pubspec.yaml file and you're good to go. Well, you'll still need to read a bit to learn how to use FormFlex.

But don't worry, we will continue improving it and making it easier to use.

Usage

Architecture

The following components make up a Flex Form:

1. FormBloc - A base class which extends the Bloc class and provides all of the functionalities for a form. It requires a FormValidationProvider<FormDataEntity> and a FormInputDataMapper which are needed by the extended FormBloc.
2. FormValidationProvider - An interface defining validation functionalities used by the base FormBloc to validate a form.
3. FormDataProvider - An optional component for loading and submitting a form. This is useful for forms that need to load data from or submit data to remote APIs.
4. FormInputDataMapper - An interface defining functionalities for mapping between a form's "presentation" data (i.e. Map<FormFieldId, dynamic>) and the form's data model (i.e. FormDataEntity).
5. FormDataEntity - A base Equatable class to be extended by a form to represent a form's data.
6. FormFieldConfig - Defines a set of configurations for a form field which is used by FormBloc to handle specific events triggered by the form field. (E.g. OnChange, etc.)
7. InputViewModel - A Union class including classes that define the data for a form field based on the type of that field. (e.g. FormFieldConfig.text, FormFieldConfig.singleSelect, FormFieldConfig.multipleSelect, and FormFieldConfig.toggledValue)
8. FormVM - Contains the data for the whole form during the form's life cycle.
9. FormComponent - A Flutter widget which is used to wrap around the form UI to be built. FormComponent allows forms to specify either a FormDataBuilder or a FormInputBuilder. Use the FormDataBuilder when building forms with custom UI and use FormInputBuilder to build a form with the set of TextInputs returned by the builder.
10. validateField - A utility function for validating a form field's value against its FormFieldConfig.
11. getValidationMessage - A utility function for getting the validation message for an invalid FormFieldValidation.

How to Implement a Form

1. Extend the FormDataEntity class to define the data for the form and override the Equatable's props getter. This is required by the FormValidationProvider to check if the form is valid as form's inputs change.
2. Optionally extend the FormValidationProvider base class to provide custom implementations for the isDirty, isValid, validate and validateUponSubmission APIs.
3. Implements the FormInputDataMapper interface to provide mapping functionalities between the form's input map and the form's FormDataEntity.
4. Extends FormBloc and provides a constructor which crates an instance of a FormBloc with an initial FormBlocState, a Map<FormFieldId, FormFieldConfig> inputConfigMap, an instance of the extended InputDataMapper class, an optional FormValidationProvider and an optional FormDataProvider.

To FormFlex in action, check out the form_with_data_builder.dart and form_with_text_input_builder.dart examples located in the /demo folder. These examples demonstrate how to build a form with the FormInputBuilder and FormDataBuilder builders.

Example of a form built with a TextInputBuilder

    FormComponent(
      bloc: _changePasswordFormBloc,
      textInputBuilder: ({
        required textInputs,
        required context,
        buttonText,
        canSubmit,
        cancelButtonText,
        onSubmit,
      }) {
        return Column(
          mainAxisAlignment: MainAxisAlignment.start,
          children: [
            Text(
              _changePasswordFormBloc.state.data.title!,
              style: Theme.of(context).textTheme.titleLarge,
            ),
            const SizedBox(height: 25),
            ...textInputs,
            const SizedBox(
              height: 35,
            ),
            TextButton(
              onPressed: canSubmit == true ? () {} : null,
              style: TextButton.styleFrom(
                backgroundColor: Theme.of(context).colorScheme.primary,
                foregroundColor:
                    Theme.of(context).textTheme.titleLarge!.color,
              ),
              child: Text(buttonText!),
            )
          ],
        );
      },
    )

Example of a form built with a DataBuilder

    FormComponent(
      bloc: _changePasswordFormBloc,
      dataBuilder: (
          {
          required inputMap,
          required context,
          buttonText,
          canSubmit,
          cancelButtonText,
          focusNodeMap,
          isLoading,
          isSubmitting,
          onChangeCallbackMap,
          onSubmit,
          textControllerMap}) {
        final oldPasswordViewModel =
            inputMap[FormFieldId.fd0] as TextInputViewModel;
        final newPasswordViewModel =
            inputMap[FormFieldId.fd1] as TextInputViewModel;
        final confirmNewPasswordViewModel =
            inputMap[FormFieldId.fd2] as TextInputViewModel;

        obscurityInputMap ??= <FormFieldId, bool>{
          FormFieldId.fd0: oldPasswordViewModel.isInputObscured,
          FormFieldId.fd1: newPasswordViewModel.isInputObscured,
          FormFieldId.fd2: confirmNewPasswordViewModel.isInputObscured,
        };
        return Column(
          mainAxisAlignment: MainAxisAlignment.start,
          children: [
            Text(
              _changePasswordFormBloc.state.data.title!,
              style: Theme.of(context).textTheme.titleLarge,
            ),
            const SizedBox(height: 25),
            ...inputMap.keys.map(
              (fieldId) => Column(
                children: [
                  const SizedBox(height: 10),
                  StatefulBuilder(
                    builder: (context, setState) {
                      return TextInput(
                        theme: theme.textInputTheme,
                        viewModel:
                            (inputMap[fieldId] as TextInputViewModel)
                                .copyWith(
                                    isInputObscured:
                                        obscurityInputMap![fieldId]!),
                        focusNode: focusNodeMap![fieldId]!,
                        controller: textControllerMap![fieldId],
                        onChange: onChangeCallbackMap![fieldId]!,
                        suffixIcon: IconButton(
                          onPressed: () => setState(() =>
                              obscurityInputMap![fieldId] =
                                  !obscurityInputMap![fieldId]!),
                          icon: const Icon(Icons.visibility),
                        ),
                      );
                    },
                  ),
                ],
              ),
            ),
            const SizedBox(
              height: 35,
            ),
            TextButton(
              onPressed: canSubmit == true ? () {} : null,
              style: TextButton.styleFrom(
                backgroundColor: Theme.of(context).colorScheme.primary,
                foregroundColor:
                    Theme.of(context).textTheme.titleLarge!.color,
              ),
              child: Text(buttonText!),
            )
          ],
        );
      },
    )

Additional information

1. To run the live demo of the examples, configure melos and use it to run the demo package by running melos build:form-demo to build the package, then running flutter run -t demo/lib/main.dart -d chrome (or melos run:demo) to run the demo Flutter app.

[flex_form_demo.png]

View Live Demo

2. For more details about how the FlexForm works, refer to this Medium [TBD] article.

Developers

How to build FormFlex

1. Run the following command to do a clean build of all of the packages (i.e. flex_form and flex_form_demo) in the project.

melos clean-build:form

2. Optionally the following commands to build each package separately.

melos build:form

melos build:form-demo

3. Lint the project before opening a PR by running

melos analyze

How test form changes

1. Run the existing to view a demo of different form examples

melos run:demo

2. Add new examples by creating a new feature folder under the /demo/features folder.

How to contribute

Contribution from the community is welcomed. Please feel free to open a PR.

TODOs

1. ✅ Convert FormValidationProvider into a base class.
2. ❌ Add documentation and tutorials
3. ❌ Add code generation and other tools to improve development workflow
4. ❌ Add Tests