RxEffects

Reactive state and effect management with RxJS.

Overview

The library provides a way to describe business and application logic using MVC-like architecture. Core elements include actions and effects, states and stores. All of them are optionated and can be used separately. The core package is framework-agnostic and can be used in different cases: libraries, server apps, web, SPA and micro-frontends apps.

The library is inspired by MVC, RxJS, Akita, JetState and Effector.

It is recommended to use RxEffects together with Ditox.js – a dependency injection container.

Features

• Reactive state and store
• Declarative actions and effects
• Effect container
• Framework-agnostic
• Functional API
• Typescript typings

Breaking changes

Version 1.0 contains breaking changes due stabilizing API from the early stage. The previous API is available in 0.7.2 version.

Documentation is coming soon.

Packages

Package	Description	Links
@hutechtechnical/impedit-beatae-repudiandae-minima	Core elements, state and effect management	Docs, API
@hutechtechnical/impedit-beatae-repudiandae-minima-react	Tooling for React.js	Docs, API

Usage

Installation

npm install @hutechtechnical/impedit-beatae-repudiandae-minima @hutechtechnical/impedit-beatae-repudiandae-minima-react --save

Concepts

The main idea is to use the classic MVC pattern with event-based models (state stores) and reactive controllers (actions and effects). The view subscribes to model changes (state queries) of the controller and requests the controller to do some actions.

Core elements:

• State – a data model.
• Query – a getter and subscriber for data of the state.
• StateMutation – a pure function which changes the state.
• Store – a state storage, it provides methods to update and subscribe the state.
• Action – an event emitter.
• Effect – a business logic which handles the action and makes state changes and side effects.
• Controller – a controller type for effects and business logic
• Scope – a controller-like boundary for effects and business logic

Example

Below is an implementation of the pizza shop, which allows order pizza from the menu and to submit the cart. The controller orchestrate the state store and side effects. The component renders the state and reacts on user events.

1// pizzaShop.ts
2
3import {
4  Controller,
5  createAction,
6  createScope,
7  declareStateUpdates,
8  EffectState,
9  Query,
10  withStoreUpdates,
11} from '@hutechtechnical/impedit-beatae-repudiandae-minima';
12import { delay, filter, map, mapTo, of } from 'rxjs';
13
14// The state
15type CartState = Readonly<{ orders: Array<string> }>;
16
17// Declare the initial state.
18const CART_STATE: CartState = { orders: [] };
19
20// Declare updates of the state.
21const CART_STATE_UPDATES = declareStateUpdates<CartState>({
22  addPizzaToCart: (name: string) => (state) => ({
23    ...state,
24    orders: [...state.orders, name],
25  }),
26
27  removePizzaFromCart: (name: string) => (state) => ({
28    ...state,
29    orders: state.orders.filter((order) => order !== name),
30  }),
31});
32
33// Declaring the controller.
34// It should provide methods for triggering the actions,
35// and queries or observables for subscribing to data.
36export type PizzaShopController = Controller<{
37  ordersQuery: Query<Array<string>>;
38
39  addPizza: (name: string) => void;
40  removePizza: (name: string) => void;
41  submitCart: () => void;
42  submitState: EffectState<Array<string>>;
43}>;
44
45export function createPizzaShopController(): PizzaShopController {
46  // Creates the scope to track subscriptions
47  const scope = createScope();
48
49  // Creates the state store
50  const store = withStoreUpdates(
51    scope.createStore(CART_STATE),
52    CART_STATE_UPDATES,
53  );
54
55  // Creates queries for the state data
56  const ordersQuery = store.query((state) => state.orders);
57
58  // Introduces actions
59  const addPizza = createAction<string>();
60  const removePizza = createAction<string>();
61  const submitCart = createAction();
62
63  // Handle simple actions
64  scope.handle(addPizza, (order) => store.updates.addPizzaToCart(order));
65
66  scope.handle(removePizza, (name) => store.updates.removePizzaFromCart(name));
67
68  // Create a effect in a general way
69  const submitEffect = scope.createEffect<Array<string>>((orders) => {
70    // Sending an async request to a server
71    return of(orders).pipe(delay(1000), mapTo(undefined));
72  });
73
74  // Effect can handle `Observable` and `Action`. It allows to filter action events
75  // and transform data which is passed to effect's handler.
76  submitEffect.handle(
77    submitCart.event$.pipe(
78      map(() => ordersQuery.get()),
79      filter((orders) => !submitEffect.pending.get() && orders.length > 0),
80    ),
81  );
82
83  // Effect's results can be used as actions
84  scope.handle(submitEffect.done$, () => store.set(CART_STATE));
85
86  return {
87    ordersQuery,
88    addPizza,
89    removePizza,
90    submitCart,
91    submitState: submitEffect,
92    destroy: () => scope.destroy(),
93  };
94}

1// pizzaShopComponent.tsx
2
3import React, { FC, useEffect } from 'react';
4import { useConst, useObservable, useQuery } from '@hutechtechnical/impedit-beatae-repudiandae-minima-react';
5import { createPizzaShopController } from './pizzaShop';
6
7export const PizzaShopComponent: FC = () => {
8  // Creates the controller and destroy it on unmounting the component
9  const controller = useConst(() => createPizzaShopController());
10  useEffect(() => controller.destroy, [controller]);
11
12  // The same creation can be achieved by using `useController()` helper:
13  // const controller = useController(createPizzaShopController);
14
15  // Using the controller
16  const { ordersQuery, addPizza, removePizza, submitCart, submitState } =
17    controller;
18
19  // Subscribing to state data and the effect stata
20  const orders = useQuery(ordersQuery);
21  const isPending = useQuery(submitState.pending);
22  const submitError = useObservable(submitState.error$, undefined);
23
24  return (
25    <>
26      <h1>Pizza Shop</h1>
27
28      <h2>Menu</h2>
29      <ul>
30        <li>
31          Pepperoni
32          <button disabled={isPending} onClick={() => addPizza('Pepperoni')}>
33            Add
34          </button>
35        </li>
36
37        <li>
38          Margherita
39          <button disabled={isPending} onClick={() => addPizza('Margherita')}>
40            Add
41          </button>
42        </li>
43      </ul>
44
45      <h2>Cart</h2>
46      <ul>
47        {orders.map((name) => (
48          <li>
49            {name}
50            <button disabled={isPending} onClick={() => removePizza(name)}>
51              Remove
52            </button>
53          </li>
54        ))}
55      </ul>
56
57      <button disabled={isPending || orders.length === 0} onClick={submitCart}>
58        Submit
59      </button>
60
61      {submitError && <div>Failed to submit the cart</div>}
62    </>
63  );
64};

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© 2021 Mikhail Nasyrov, MIT license