Redux Decorators

A ridiculously good syntax for working with Redux using decorators in ES7 / TypeScript. Currently limited to Angular 2 but could potentially be used elsewhere.

Try a live example on plunkr

Installation

npm i redux-decorators

Example Usage (Angular 2)

app.reducer.ts

import {InitialState, Reducer} from 'redux-decorators';

@InitialState({
    count: 0
})
@Reducer('add', 'remove')
export class AppReducer {
    add(state) { return { count: state.count + 1 }; }
    remove(state) { return { count: state.count - 1 }; }
}

In the above example we create a new class that will hold our action reducers. We then register two action reducers with the @Reducer('add', 'remove') decorator. Anytime an add or remove action is dispatched the corresponding method will be called on the AppReducer class, allowing the method to update the state for that particular action.

count.component.ts

import {Component} from 'angular2/core';
import {Store} from 'redux-decorators';

@Component({
    selector: 'counter',
    template: `
        <div>Count: {{count}}</div>
        <button (click)="dispatch('add')">Add</button>
        <button (click)="dispatch('remove')">Remove</button>
    `
})

@Store('count')
export class CounterComponent {}

In the above example we used the @Store() decorator to register the CounterComponent as a store observer. We also registered the count property with the store which means that any changes to the count property in the application state will be automatically pushed through to the count property of this component.

Notice also the dispatch() method in the template. This method is provided by the @Store() decorator and can be used to easily dispatch an action.

boot.ts

import {bootstrap} from 'angular2/platform/browser';
import {AppComponent} from './app.component';
import './app.reducer';

bootstrap(AppComponent);

In the above example we imported the app.reducer as a side-effect only module - that's all we need to do.

API

Decorators

@InitialState(state)

The @InitialState decorator is used for setting the initial state of the application store.

This decorator accepts a single object state that describes the initial state of the application.

@InitialState({
    count: 0
})

@Reducer([actionReducer1, actionReducer2, ...])

The Reducer() decorator is used to identify a root reducer, however it can also be used as a convenience method for setting multiple action reducers in a single call.

The @Reducer() decorator registers a new root reducer if the class you are decorating contains a reducer method.

Root Reducer

@Reducer()
class MyRootReducer implements IReducer {
    reducer(state = initialState, action) {
       ...
    }
}

In the above example, the MyRootReducer class contains a reducer method, this means that this class will be registered as the root reducer - this will overwrite the default root reducer and prevent action reducers from working out of the box.

Action Reducers
We can mark individual methods as action reducers.

class MyReducers {
    @Reducer() add(state): { return { count: state.count + 1; } }
    @Reducer() remove(state): { return { count: state.count - 1; } }
}

Alternatively we can mark multiple methods at once using @Reducer():

@Reducer('add', 'remove')
class MyReducers {
    add(state): { return { count: state.count + 1; } }
    remove(state): { return { count: state.count - 1; } }
}

@Store([stateProp1, stateProp2, ...])

The @Store() decorator is used to identify a store component. A store component is automatically subscribed to the application store and receives registered state updates when the store is updated.

@Store()
class TodoListComponent {
   ...
}

You'll also need to declare which properties are updated by the application store. You can do that by explicitly decorating each property with the @State() decorator, or you can declare these properties when you declare the @Store() decorator:

@Store('todos')
class TodoListComponent {
   ...
}

In the above example we are declaring that the todos property of the TodoListComponent should be automatically updated whenever the application store's todos property is changed.

@State()

The @State() decorator is used to identify a state property in the application store. Identifying state properties allow the property to be automatically updated when the application store's property changes.

@Store()
class TodoListComponent {
   @State() todos:Todo[] = [];
   ...
}

In the above example we are declaring that the todos property of the TodoListComponent should be automatically updated whenever the application store's todos property is changed. Please also refer to the @Store() equivalent.

License

MIT

pkamdem/redux-decorators