shape

Description:

shape

▲ Shape #
A package for building forms that can be easily reused, validated, and parsed, primarily for Flutter apps.
Table of Contents #

▲ Shape

Table of Contents
Summary
Usage
Principle
Features

Access parsed values
Automatic form error generation


Example



Summary #
This package comes in three parts:

The shape package that contains the primary classes and annotations used for creating form bodies.
The shape_generator package, which is the code generator that runs on classes annotated with @GenerateFormBody().
The shape_starter_kit package, which contains a set of generic and commonly used form fields and functions for use with the shape package.

Usage #
First, add the shape package to your project's dependencies using dart pub add or flutter pub add.
dart pub add shape
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Then, add the shape_generator and build_runner packages to your project's dev dependencies using the same CLI.
dart pub add --dev shape_generator build_runner
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Note
If these commands don't work for you, consider adding the packages manually to your pubspec.yaml file by placing the shape package under dependencies and the shape_generator and build_runner packages under dev_dependencies.

To generate a form body, in this case called ExampleFormBody;

Create an abstract class ExampleFormBody annotated with @GenerateFormBody().
Add the _$ExampleFormBodyFields mixin.
Create a single unnamed factory that returns an instance of _$ExampleFormBody containing all form fields that should be present in the form body. All parameters must be an instance of a class that extends FormField, a class provided by this package.

A full example might look like this:
import 'package:shape/shape.dart';
import 'package:shape_addons/shape_addons.dart';

part 'example_form_body.g.dart';

@GenerateFormBody()
abstract class ExampleFormBody with _$ExampleFormBodyFields {
factory ExampleFormBody({
required String? foo,
required String? bar,
}) {
return _$ExampleFormBody(
name: GenericFormField(
value: foo,
isRequired: true,
),
otherName: RangedDoubleFormField(
value: bar,
),
);
}
}

void main() {
final formBody = ExampleFormBody();
}
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Principle #
Shape works by separating form fields, bodies, validation logic and parsing logic into separate classes.
Form bodies are a collection of form fields. The flow of data going into and coming out of a form body looks as follows:
flowchart TD
classDef multipleValues fill:#f0f0f0,stroke:#000000,stroke-dasharray: 5;
classDef classInstance fill:#eeeeff,stroke:#aaaaee
classDef function fill:#d0efe6,stroke:#6cddbd

raw{{Raw String values}}:::multipleValues
fbc(Form body constructor):::function
fbi[Form body instance]:::classInstance
parsed{{Parsed values}}:::multipleValues
fei[Form errors instance]:::classInstance

raw -- "are given to" --> fbc
fbc -- "parses fields and creates" --> fbi
fbi -- "contains" --> parsed
fbi -- "when calling validate() creates" --> fei
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Features #
Access parsed values
Form bodies take in raw values and produce parsed values. Whenever a form body is constructed or copied (using copyWith), the values are automatically parsed and accessible as properties with the same name as the original field.
var formBody = TaxFormBody(vatPercentage: null);
print(formBody.vatPercentage); // null

formBody = formBody.copyWith(vatPercentage: '0.0');
print(formBody.vatPercentage); // Percent('0%')
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Automatic form error generation
When generating a form body, an adjacent [FormErrors] class is also created and accessible.
var formBody = TaxFormBody(vatPercentage: null);
print(formBody.validate()) // TaxFormErrors(vatPercentage: PercentValidationError.empty)

formBody = formBody.copyWith(vatPercentage: 'abc');
print(formBody.validate()) // TaxFormErrors(vatPercentage: PercentValidationError.invalid)

formBody = formBody.copyWith(vatPercentage: '2.0');
print(formBody.validate()) // TaxFormErrors(vatPercentage: null)
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Example #
To run the example, run build_runner in the example folder.
cd example
flutter pub run build_runner build --delete-conflicting-outputs
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A new form body will be generated based on the contents of example/lib/example_form_body.dart. After the code generator has completed, examine the contents of the file example/lib/example_form_body.g.dart.

License

For personal and professional use. You cannot resell or redistribute these repositories in their original state.

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