Redux Chains

Nested reducers made easy.

This is just a small helper function that allows you to call several reducers in chain and keep the state object reference intact if the state is not modified by any of them.

Usage

In order to keep app components self-contained and nicely nested, we could use the following folder structure:

App/
|
| Sidebar/
|   |
|   | LanguageSelector/
|   |   | index.js
|   |   | actions.js
|   |   | reducers.js
|   |   | styles.css
|   |   | ...
|   |
|   | ItemList/
|   |   | index.js
|   |   | actions.js
|   |   | reducers.js
|   |   | styles.css
|   |   | ...
|   |
|   | index.js
|   | actions.js
|   | reducers.js
|   | styles.css
|   | ...
| ...

Each component contains its own set of actions and reduces the state for them.

In order to enforce a parent-child structure, parents must call their direct child reducers in order to give them the chance to reduce the state.

In this example:

App/Sidebar/actions.js

export const CLOSE_SIDEBAR = 'CLOSE_SIDEBAR';
export const OPEN_SIDEBAR = 'OPEN_SIDEBAR';

export const closeSidebar = (payload = null) => ({type: CLOSE_SIDEBAR, payload});
export const openSidebar = (payload = null) => ({type: OPEN_SIDEBAR, payload});

App/Sidebar/reducers.js

import chainReducers from "redux-chains"
import * as actions from './actions'
import itemListReducer from "./ItemList/reducers"
import languageSelectorReducer from "./LanguageSelector/reducers"

function sidebarReducer(state, action) {

    switch (action.type) {

        case actions.CLOSE_SIDEBAR:
            return {
                ...state,
                sidebarOpened: false,
            };

        case actions.OPEN_SIDEBAR:
            return {
                ...state,
                sidebarOpened: true,
            };

        default:
            return state;
    }
}

export default function reducers(state, action) {
    return chainReducers(
        sidebarReducer,
        itemListReducer,
        languageSelectorReducer,
    )(state, action);
}

In turn, each child component must call its own child reducers following the same method.