GitLocker: The Coding Marketplace

Description:

over react

OverReact #
A library for building statically-typed React UI components using Dart.
This library also exposes OverReact Redux, which has its own documentation.

Migration Guides
Using OverReact

Running tests in your project

OverReact Component Unit Test Examples

Anatomy of an OverReact component

UiFactory
UiProps
UiState
UiComponent2

Fluent-style component consumption
DOM components and props
Component Formatting
Building custom components

Component Boilerplates
Component Best Practices

Contributing

Migration Guides #
Null safety #
over_react 5.0.0 introduces support for null safety.
Now, you can declare non-nullable required props, using the late keyword. See the docs null safety and required props for more information.
To migrate components to null safety, see our null safety migration guide.
More Migration Guides #

New component boilerplate: How to update to the mixin-based (mixin MyProps on UiProps {}) over_react component declaration syntax.
UiComponent2: How to move off the deprecated UiComponent base class and onto UiComponent2.
BuiltRedux to Redux: How to transition to OverReact Redux from BuiltRedux.
Flux to Redux: A guide to how to transition from w_flux to OverReact Redux. This guide also introduces a new architecture, Influx, that can be used for incremental refactors.
Dart2 Migration: Documentation on the Dart 2 builder updates and how to transition componentry to Dart 2.

Using OverReact #

Prerequisites

Familiarize yourself with React JS
Since OverReact is built atop React JS, we strongly encourage you to gain familiarity with it by reading some React JS tutorials first.

Familiarize yourself with Dart Web applications
If you have never built a Web application in Dart, we strongly encourage you to gain familiarity with the core terminology, tools and boilerplate necessary to serve an application locally using Dart. Dart has fantastic documentation and tutorials to get you started.

Add the over_react package as a dependency in your pubspec.yaml.
dependencies:
over_react: ^4.0.0
copied to clipboard

Enable the OverReact Analyzer Plugin (beta), which has many lints and assists to make authoring OverReact components easier!

Include the native JavaScript react and react_dom libraries in your app’s index.html file,
and add an HTML element with a unique identifier where you’ll mount your OverReact UI component(s).
<html>
<head>

</head>
<body>
<div id="react_mount_point">
// OverReact component render() output will show up here.
</div>

<script src="packages/react/react.js"></script>
<script src="packages/react/react_dom.js"></script>


<script type="application/javascript" defer src="index.dart.js"></script>
</body>
</html>
copied to clipboard

Note: When serving your application in production, use packages/react/react_with_react_dom_prod.js
file instead of the un-minified react.js / react_dom.js files shown in the example above.

Import the over_react and react_dom libraries into index.dart. Then build some components and mount / render a React tree within the HTML element you created in the previous step by calling react_dom.render() within the main() entrypoint of your Dart application.

Be sure to namespace the react_dom.dart import as react_dom to avoid collisions with UiComponent.render
when creating custom components.

import 'dart:html';
import 'package:over_react/react_dom.dart' as react_dom;
import 'package:over_react/over_react.dart';

// Example of where the `Foo` component might be exported from
import 'package:your_package_name/foo.dart';

main() {
// Mount / render your component/application.
react_dom.render(
Foo()(),
querySelector('#react_mount_point'),
);
}
copied to clipboard

Run webdev serve in the root of your Dart project.

Note: If you're not using the latest component boilerplate, you'll have to restart your analysis server in your IDE for the built types to resolve properly after the build completes. Unfortunately, this is a known limitation in the analysis server at this time.
Migrate your components to the latest component boilerplate to never worry about this again!

Running unit tests in your project #
When running unit tests on code that uses the over_react builder (or any code that imports over_react),
you must run your tests using the build_runner package.

Warning: Do not run tests via pub run build_runner test in a package while another instance of build_runner
(e.g. pub run build_runner serve) is running in that same package. This workflow is unsupported by build_runner

Run tests using the build_runner package, and specify the platform to be a browser platform. Example:
$ pub run build_runner test -- -p chrome test/your_test_file.dart
copied to clipboard

OverReact Component Unit Test Examples
Below are links to a UI component from our example "Todo App", and its analogous tests that we've written for components we use in . We utilize the utilities found in our over_react_test library.

TodoListItem

Component Definition
Component Unit Tests
"Connected" OverReact Redux Unit Tests

Anatomy of an OverReact component #

If you are not familiar with React JS
Since OverReact is built atop React JS, we strongly encourage you to gain
familiarity with it by reading this React JS tutorial first.

The over_react library functions as an additional "layer" atop the Dart react package
which handles the underlying JS interop that wraps around React JS.
The library strives to maintain a 1:1 relationship with the React JS component class and API.
To do that, an OverReact component is comprised of four core pieces that are each wired up
via our builder.

UiFactory
UiProps
component, either a:

function component uiFunction
class component UiComponent2 (and optionally a UiState)

UiFactory #
UiFactory is a function that returns a new instance of a component's UiProps class.
// Class component
UiFactory<FooProps> Foo = castUiFactory(_$Foo);

// Function component
UiFactory<FooProps> Foo = uiFunction((props) { /*...*/ }, _$FooConfig);
copied to clipboard

This factory is the entry-point to consuming any OverReact component.
The UiProps instance it returns can be used as a component builder,
or as a typed view into an existing props map.
castUiFactory is necessary to prevent implicit cast analysis warnings before code generation has been run.

UiProps #
UiProps is a Map class that adds statically-typed getters and setters for each React component prop.
It can also be invoked as a function, serving as a builder for its analogous component.
mixin FooProps on UiProps {
// ... the props for your component go here
String? bar;
bool? baz;
List<int>? bizzles;
}
copied to clipboard

Note: The builder generates a class with getters and setters overriding the fields you declare in your mixin, but you don't need to worry about that generated class. To use props from another mixin, simply mix it in! See "With other mixins" below for more information.

With other mixins
To compose props mixin classes, create a class alias that uses UiProps as the base and mix in multiple props mixins. The generated props implementation will then use it as the base class and implement the generated version of those props mixins.
UiFactory<FooProps> Foo = castUiFactory(_$Foo); // ignore: undefined_identifier

mixin FooPropsMixin on UiProps {
String? bar;
bool? baz;
List<int>? bizzles;
}

class FooProps = UiProps with FooPropsMixin, BarPropsMixin;

class FooComponent extends UiComponent2<FooProps> {
// ...
}
copied to clipboard
Composition
The use-case for composing multiple props mixins into a single component props class is typically a component that renders another component, and therefore needs to expose the prop interface of that child component which will get forwarded via addUnconsumedProps.
Check out an example of props mixin component composition here

UiProps as a Map

Warning
Directly reading late required props on arbitrary maps is unsafe.
See the docs on Unsafe Required Prop Reads
for more information and for instructions on how to read these props safely.

UiFactory<FooProps> Foo = castUiFactory(_$Foo); // ignore: undefined_identifier

mixin FooProps on UiProps {
String? color;
}

class FooComponent extends UiComponent2<FooProps> {
// ...
}

void bar() {
FooProps props = Foo();

props.color = '#66cc00';

print(props.color); // #66cc00
print(props); // {FooProps.color: #66cc00}
}

/// You can also use the factory to create a UiProps instance
/// backed by an existing Map.
void baz() {
Map existingMap = {'FooProps.color': '#0094ff'};

FooProps props = Foo(existingMap);

print(props.color); // #0094ff
}
copied to clipboard

UiProps as a builder
UiFactory<FooProps> Foo = castUiFactory(_$Foo); // ignore: undefined_identifier

mixin FooProps on UiProps {
String? color;
}

class FooComponent extends UiComponent2<FooProps> {
ReactElement bar() {
// Create a UiProps instance to serve as a builder
FooProps builder = Foo();

// Set some prop values
builder
..id = 'the_best_foo'
..color = '#ee2724';

// Invoke as a function with the desired children
// to return a new instance of the component.
return builder('child1', 'child2');
}

/// Even better... do it inline! (a.k.a fluent)
ReactElement baz() {
return (Foo()
..id = 'the_best_foo'
..color = 'red'
)(
'child1',
'child2'
);
}
}
copied to clipboard

See fluent-style component consumption for more examples on builder usage.

UiState #
UiState is a Map class (just like UiProps) that adds statically-typed getters and setters
for each React component state property in a class component.
mixin FooState on UiState {
// ...
}
copied to clipboard

UiState is optional, and won’t be used for every component. Check out the UiStatefulComponent boilerplate for more information.

Note: The builder will make the concrete getters and setters available from the mixin fields you author in a generated class. To mix state classes together, the mixin class should be used rather than the generated props class. See "With other mixins" above for more information.

UiComponent2 (class-based components) #

For guidance on updating to UiComponent2 from UiComponent, check out the UiComponent2 Migration Guide.

UiComponent2 is a subclass of react.Component2, containing lifecycle methods and rendering logic for components.
class FooComponent extends UiComponent2<FooProps> {
// ...
}
copied to clipboard

This class provides statically-typed props via UiProps, as well as utilities for prop forwarding and CSS class merging.
The UiStatefulComponent2 flavor augments UiComponent2 behavior with statically-typed state via UiState.

uiFunction (function components) #
uiFunction lets you declare a function component.
In JavaScript, function components are just plain functions, but in over_react this wrapper is needed to perform JS interop and wire up the typed props class.
mixin FooProps on UiProps {
bool? isDisabled;
List? items;
}

UiFactory<FooProps> Foo = uiFunction((props) {
// Set default props using null-aware operators.
final isDisabled = props.isDisabled ?? false;
final items = props.items ?? [];

// Return the rendered component contents here.
return Fragment()(
Dom.div()(items),
(Dom.button()..disabled = isDisabled)('Click me!'),
);
}, _$FooConfig); // The generated props config will match the factory name.

usageExample() => (Foo()..items = ['bar'])();
copied to clipboard

Accessing and manipulating props / state within UiComponent2

Within the UiComponent2 class, props and state are not just Maps.
They are instances of UiProps and UiState, which means you don’t need String keys to access them!
newProps() and newState() are also exposed to conveniently create empty instances of UiProps and UiState as needed.
typedPropsFactory() and typedStateFactory() are also exposed to conveniently create typed props / state objects out of any provided backing map.

UiFactory<FooProps> Foo = castUiFactory(_$Foo); // ignore: undefined_identifier

mixin FooProps on UiProps {
late String color;
Function()? onDidActivate;
Function()? onDidDeactivate;
}
mixin FooState on UiState {
late bool isActive;
}

class FooComponent extends UiStatefulComponent2<FooProps, FooState> {
@override
Map get defaultProps => (newProps()
..color = '#66cc00'
);

@override
Map get initialState => (newState()
..isActive = false
);

@override
void componentDidUpdate(Map prevProps, Map prevState, [dynamic snapshot]) {
var tPrevState = typedStateFactory(prevState);
var tPrevProps = typedPropsFactory(prevProps);

if (state.isActive && !tPrevState.isActive) {
props.onDidActivate?.call();
} else if (!state.isActive && tPrevState.isActive) {
props.onDidDeactivate?.call();
}
}

@override
dynamic render() {
return (Dom.div()
..modifyProps(addUnconsumedDomProps)
..style = {
...newStyleFromProps(props),
'color': props.color,
'fontWeight': state.isActive ? 'bold' : 'normal',
}
)(
(Dom.button()..onClick = _handleButtonClick)('Toggle'),
props.children,
);
}

void _handleButtonClick(SyntheticMouseEvent event) {
setState(newState()
..isActive = !state.isActive
);
}
}
copied to clipboard

Fluent-style component consumption #

The OverReact analyzer plugin has many lints and assists to make authoring OverReact components easier!

In OverReact, components are consumed by invoking a UiFactory to return a new UiProps builder, which is then modified and invoked to build a ReactElement.
This is done to make "fluent-style" component consumption possible, so that the OverReact consumer experience is very similar to the React JS / "vanilla" react-dart
experience.
To demonstrate the similarities, the example below shows a render method for JS, JSX, react-dart, and over_react that will have the exact same HTML markup result.

React JS:
render() {
return React.createElement('div', {className: 'container'},
React.createElement('h1', null, 'Click the button!'),
React.createElement('button', {
id: 'main_button',
onClick: _handleClick
}, 'Click me')
);
}
copied to clipboard

React JS (JSX):
render() {
return <div className="container">
<h1>Click the button!</h1>
<button
id="main_button"
onClick={_handleClick}
>Click me</button>
</div>;
}
copied to clipboard

Vanilla react-dart:
render() {
return react.div({'className': 'container'},
react.h1({}, 'Click the button!'),
react.button({
'id': 'main_button',
'onClick': _handleClick
}, 'Click me')
);
}
copied to clipboard

OverReact:
render() {
return (Dom.div()..className = 'container')(
Dom.h1()('Click the button!'),
(Dom.button()
..id = 'main_button'
..onClick = _handleClick
)('Click me')
);
}
copied to clipboard
Let’s break down the OverReact fluent-style shown above
render() {
// Create a builder for a <div>,
// add a CSS class name by cascading a typed setter,
// and invoke the builder with the HTML DOM <h1> and <button> children.
return (Dom.div()..className = 'container')(

// Create a builder for an <h1> and invoke it with children.
// No need for wrapping parentheses, since no props are added.
Dom.h1()('Click the button!'),

// Create a builder for a <button>,
(Dom.button()
// add a ubiquitous DOM prop exposed on all components,
// which Dom.button() forwards to its rendered DOM,
..id = 'main_button'
// add another prop,
..onClick = _handleClick
// and finally invoke the builder with children.
)('Click me')
);
}
copied to clipboard

DOM components and props #
All react-dart DOM components (react.div, react.a, etc.) have a
corresponding Dom method (Dom.div(), Dom.a(), etc.) in OverReact.
ReactElement renderLink() {
return (Dom.a()
..id = 'home_link'
..href = '/home'
)('Home');
}

ReactElement renderResizeHandle() {
return (Dom.div()
..className = 'resize-handle'
..onMouseDown = _startDrag
)();
}
copied to clipboard

OverReact DOM components return a new DomProps builder, which can be used
to render them via our fluent interface
as shown in the examples above.

DomProps has statically-typed getters and setters for all HTML attribute props.

The domProps() function is also available to create a new typed Map or a typed view into an existing Map. Useful for manipulating DOM props and adding DOM props to components that don’t forward them directly, or to access a DOM prop from a plain map in a lifecycle method as shown below.
@override
void componentDidUpdate(Map prevProps, Map prevState, [dynamic snapshot]) {
// Say you want to compare the previous / current value of `DomProps.title` here...
final titleChanged = domProps(prevProps).title != props.title;
}
copied to clipboard

Component Formatting #

A note on dart_style:
Currently, dart_style (dartfmt) decreases the readability of components
built using OverReact's fluent-style.
See https://github.com/dart-lang/dart_style/issues/549 for more info.
We're exploring some different ideas to improve automated formatting, but for the time being, we do not recommend using dart_style with OverReact.
However, if you do choose to use dart_style, you can greatly improve its output by using trailing commas in children argument lists:

dart_style formatting:

return (Button()
..id = 'flip'
..skin =
ButtonSkin.vanilla)((Dom.span()
..className = 'flip-container')((Dom.span()..className = 'flipper')(
(Dom.span()
..className =
'front-side')((Icon()..glyph = IconGlyph.CHEVRON_DOUBLE_RIGHT)()),
(Dom.span()
..className =
'back-side')((Icon()..glyph = IconGlyph.CHEVRON_DOUBLE_LEFT)()))));
copied to clipboard

dart_style formatting, when trailing commas are used:

return (Button()
..id = 'flip'
..skin = ButtonSkin.vanilla)(
(Dom.span()..className = 'flip-container')(
(Dom.span()..className = 'flipper')(
(Dom.span()..className = 'front-side')(
(Icon()..glyph = IconGlyph.CHEVRON_DOUBLE_RIGHT)(),
),
(Dom.span()..className = 'back-side')(
(Icon()..glyph = IconGlyph.CHEVRON_DOUBLE_LEFT)(),
),
),
),
);
copied to clipboard

Guidelines #
To help ensure your OverReact code is readable and consistent, we've arrived at the following formatting rules.

ALWAYS place the closing builder parent on a new line.
Good:
(Button()
..skin = ButtonSkin.SUCCESS
..isDisabled = true
)('Submit')
copied to clipboard
Bad:
(Button()
..skin = ButtonSkin.SUCCESS
..isDisabled = true)('Submit')
copied to clipboard

ALWAYS pass component children on a new line with trailing commas and 2 space indentation.
Good:
Dom.div()(
Dom.span()('nested component'),
)
copied to clipboard
Dom.div()(
Dom.span()('nested component A'),
Dom.span()('nested component B'),
)
copied to clipboard
Bad:
// Children are not on a new line; in most cases,
// this makes it difficult to quickly determine nesting.
Dom.div()(Dom.span()('nested component'), Dom.span()('nested component'))
copied to clipboard
// With nested hierarchies, continuation indents can quickly result
// in a "pyramid of Doom"
Dom.div()(
Dom.ul()(
Dom.li()(
Dom.a()('A link!')
)
)
)
copied to clipboard
// Omitting trailing commas makes it a pain to rearrange lines
Dom.div()(
Dom.span()('nested component A'),
Dom.span()('nested component B')
)
Dom.div()(
Dom.span()('nested component B') // ugh, need to add a comma here...
Dom.span()('nested component A'),
)
copied to clipboard

AVOID passing children within lists; lists should only be used when the number/order of the children are dynamic.
Good:
Dom.div()(
Dom.span()('nested component'),
Dom.span()('nested component'),
)
copied to clipboard
var children = [
Dom.div()('List of Items:'),
]..addAll(props.items.map(renderItem));

return Dom.div()(children)
copied to clipboard
Bad:
Dom.div()([
(Dom.span()..key = 'span1')('nested component'),
(Dom.span()..key = 'span2')('nested component'),
])
copied to clipboard

AVOID specifying more than one cascading prop setter on the same line.
Good:
(Dom.div()
..id = 'my_div'
..className = 'my-class'
)()
copied to clipboard
Bad:
(Dom.div()..id = 'my_div'..className = 'my-class')()
copied to clipboard

Building custom components #
Now that we’ve gone over how to use the over_react package in your project,
the anatomy of a component and the DOM components
that you get for free from OverReact, you're ready to start building your own custom React UI components.

Start with one of the component boilerplate templates below
(Or, use OverReact's code snippets for WebStorm/IntelliJ and VsCode).

Component (props only)
Stateful Component (props + state)

Fill in your props and rendering/lifecycle logic.

Consume your component with the fluent interface.

Run the app you’ve set up to consume over_react
$ webdev serve
copied to clipboard
That’s it! Code will be automatically generated on the fly by the builder!

Check out some custom component demos to get a feel for what’s possible!

Component Boilerplate Templates #

WebStorm/IntelliJ and VsCode Snippets

Component Boilerplate
import 'package:over_react/over_react.dart';
part 'foo_component.over_react.g.dart';

UiFactory<FooProps> Foo = castUiFactory(_$Foo); // ignore: undefined_identifier

mixin FooProps on UiProps {
// Props go here, declared as fields:
late bool isDisabled;
late Iterable<String> items;
}

class FooComponent extends UiComponent2<FooProps> {
@override
Map get defaultProps => (newProps()
// Cascade default props here
..isDisabled = false
..items = []
);

@override
dynamic render() {
// Return the rendered component contents here.
// The `props` variable is typed; no need for string keys!
}
}
copied to clipboard

Stateful Component Boilerplate
import 'package:over_react/over_react.dart';
part 'foo_component.over_react.g.dart';

UiFactory<BarProps> Bar = castUiFactory(_$Bar); // ignore: undefined_identifier

mixin BarProps on UiProps {
// Props go here, declared as fields:
late bool isDisabled;
late Iterable<String> items;
}

mixin BarState on UiState {
// State goes here, declared as fields:
late bool isShown;
}

class BarComponent extends UiStatefulComponent2<BarProps, BarState> {
@override
Map get defaultProps => (newProps()
// Cascade default props here
..isDisabled = false
..items = []
);

@override
Map get initialState => (newState()
// Cascade initial state here
..isShown = true
);

@override
dynamic render() {
// Return the rendered component contents here.
// The `props` variable is typed; no need for string keys!
}
}
copied to clipboard

Function Component Boilerplate
import 'package:over_react/over_react.dart';
part 'foo_component.over_react.g.dart';

UiFactory<FooProps> Foo = uiFunction(
(props) {
// Set default props using null-aware operators.
final isDisabled = props.isDisabled ?? false;
final items = props.items ?? [];

// Return the rendered component contents here.
// The `props` variable is typed; no need for string keys!
return Fragment()(
Dom.div()(items),
(Dom.button()..disabled = isDisabled)('Click me!'),
);
},
// The generated props config will match the factory name.
_$FooConfig, // ignore: undefined_identifier
);

mixin FooProps on UiProps {
// Props go here, declared as fields:
bool? isDisabled;
Iterable<String>? items;
}
copied to clipboard

Component Best Practices #

ALWAYS write informative comments for your component factories.
Include what the component relates to, relies on, or if it extends
another component.
Good:
/// Use the `DropdownButton` component to render a button
/// that controls the visibility of a child [DropdownMenu].
///
/// * Related to [Button].
/// * Extends [DropdownTrigger].
/// * Similar to [SplitButton].
///
/// See: <https://link-to-any-relevant-documentation>.
UiFactory<DropdownButtonProps> DropdownButton = castUiFactory(_$DropdownButton); // ignore: undefined_identifier
copied to clipboard
Bad:
/// Component Factory for a dropdown button component.
UiFactory<DropdownButtonProps> DropdownButton = castUiFactory(_$DropdownButton); // ignore: undefined_identifier
copied to clipboard

ALWAYS set a default / initial value for boolean props / state fields,
and document that value in a comment.
Why? Without default prop values for bool fields, they could be
null - which is extremely confusing and can lead to a lot of
unnecessary null-checking in your business logic.
Good:
mixin DropdownButtonProps on UiProps {
/// Whether the [DropdownButton] appears disabled.
///
/// Default: `false`
bool isDisabled;

/// Whether the [DropdownButton]'s child [DropdownMenu] is open
/// when the component is first mounted.
///
/// Determines the initial value of [DropdownButtonState.isOpen].
///
/// Default: `false`
bool initiallyOpen;
}

mixin DropdownButtonState on UiState {
/// Whether the [DropdownButton]'s child [DropdownMenu] is open.
///
/// Initial: [DropdownButtonProps.initiallyOpen]
bool isOpen;
}

DropdownButtonComponent
extends UiStatefulComponent2<DropdownButtonProps, DropdownButtonState> {
@override
Map get defaultProps => (newProps()
..isDisabled = false
..initiallyOpen = false
);

@override
Map get initialState => (newState()
..isOpen = props.initiallyOpen
);
}
copied to clipboard
Bad:
mixin DropdownButtonProps on UiProps {
bool isDisabled;
bool initiallyOpen;
}

mixin DropdownButtonState on UiState {
bool isOpen;
}

DropdownButtonComponent
extends UiStatefulComponent2<DropdownButtonProps, DropdownButtonState> {
// Confusing stuff is gonna happen in here with
// bool props that could be null.
}
copied to clipboard

AVOID adding props or state fields that don't have
an informative comment.
Good:
mixin DropdownButtonProps on UiProps {
/// Whether the [DropdownButton] appears disabled.
///
/// Default: `false`
bool isDisabled;

/// Whether the [DropdownButton]'s child [DropdownMenu] is open
/// when the component is first mounted.
///
/// Determines the initial value of [DropdownButtonState.isOpen].
///
/// Default: `false`
bool initiallyOpen;
}

mixin DropdownButtonState on UiState {
/// Whether the [DropdownButton]'s child [DropdownMenu] is open.
///
/// Initial: [DropdownButtonProps.initiallyOpen]
bool isOpen;
}
copied to clipboard
Bad:
mixin DropdownButtonProps on UiProps {
bool isDisabled;
bool initiallyOpen;
}

mixin DropdownButtonState on UiState {
bool isOpen;
}
copied to clipboard

Ignore Ungenerated Warnings Project-Wide
To avoid having to add // ignore: uri_has_not_been_generated to each
component library on the part/import that references generated code,
ignore this warning globally within analysis_options.yaml:
analyzer:
errors:
uri_has_not_been_generated: ignore
copied to clipboard
Alternatively, include workiva_analysis_options
which ignores this warning by default.

Contributing #
Yes please! (Please read our contributor guidelines first)

Versioning #
The over_react library adheres to Semantic Versioning:

Any API changes that are not backwards compatible will bump the major version (and reset the minor / patch).
Any new functionality that is added in a backwards-compatible manner will bump the minor version
(and reset the patch).
Any backwards-compatible bug fixes that are added will bump the patch version.