Hub Flow

Hub Flow is a pattern for managing state in React.js applications. It steals the great principles from Flux & Redux (one-way data flow), but leaves out the ceremonious complexity. Hub Flow comes with built in immutability, which means a huge performance boost and an end to accidental state mutation bugs. Hub Flow is powered by Freezer.js

npm install --save hub-flow

Getting Started

hub.ts

import createHub, { Hub } from "hub-flow";
import { DBUser, Counter } from "models";
 
// Describe the Shape of your App State
export interface AppState {
  counter: { count: number };
  // Store the server responses on App state
  // And transform the data via the Model (see below)
  // Basically, store serializable stuff on app state so
  // caching works properly
  users: DBUser[];
}
 
// Setup the default AppState
// Unless you specify, the app state will be loaded
// from cache if possible
const DEFAULT_STATE: AppState = {
  users: [],
  counter: new Counter(),
};
 
// Create the HUB
let hub = createHub(DEFAULT_STATE);
 
export default hub;

Once you setup a hub, you want to create a Model for the various slices/layers of your application state. In the Model you can

create methods that update AppState
Setup specific listeners so that your component only re-renders when it needs to.
Transform data / setup computed values
Setup relationships with other layers of the application (optionally)

counter.models.ts

import hub from "global/hub";
import { Model } from "hub-flow";
 
export class Counter extends Model<Counter> {
  getDependencies() {
    return [hub.state.counter];
  }
 
  get count() {
    return hub.state.counter.count;
  }
  increment() {
    hub.state.counter.set({ count: hub.state.counter.count + 1 });
  }
  decrement() {
    hub.state.counter.set({ count: hub.state.counter.count - 1 });
  }
  reset() {
    hub.state.counter.set({ count: 0 });
  }
}

Then use it in a React component by leveraging useModel.

import React from "react";
import { Counter } from "models";
import { useModel } from "hub-flow";
 
export function CounterDisplay() {
  console.log("CounterDisplay -> CounterDisplay");
  const counter = useModel(Counter);
  return <div>Counter: {counter.count}</div>;
}
 
export function CounterButtons() {
  console.log("CounterButtons -> CounterButtons");
  const counter = useModel(Counter);
  return (
    <div>
      <button onClick={counter.reset}>Reset</button>
      <button onClick={counter.decrement}>-1</button>
      <button onClick={counter.increment}>+1</button>
    </div>
  );
}

Under the covers, useModel hook:

Wraps your Model's contstructor witha React.useMemo so that you don't get a new instance of your model with each render
Additional params will be passed to your Model's constructor
Wires up to the listeners that you defined in your Model so that React renders any time that listener receives and update event.

useModel(Counter) => new Counter();
// Additional params will be passed to your Model's constructor
useModel(User, 3) => new User(3);