redux-batch-actions-enhancer

Store enhancer for redux, which allows single trigger of subscriptions after a bunch of actions.

Installation

npm install --save redux-batch-actions-enhancer

Usage

To add batch feature, simply provide enhancer as third parameter to redux, then you can use the built-in helper function createAction to generate a batch action containing all the actions given in parameters:

import { createStore } from 'redux';
import { batch, createAction } from 'redux-batch-actions-enhancer';

const store = createStore(reducer, initialState, batch().enhancer);

const actionA = { type: 'A' };
const actionB = { type: 'B' };
store.dispatch(createAction(actionA, actionB));

Notice that batch is a function returns enhancer which can be used in creating store. This might be helpful if there are more than one redux instance inside the app.

If you have any middleware, you can use the redux built-in function compose to combine these enhancers together:

import { createStore, applyMiddleare, compose } from 'redux';
import { batch, createAction } from 'redux-batch-actions-enhancer';
import createLogger from 'redux-logger';

const logger = createLogger();

const store = createStore(
    reducer,
    initialState,
    compose(batch().enhancer, applyMiddleware(logger)),
);

store.dispatch(createAction(actionA, actionB));

One thing to mention is that after enhancer, the batch actions will be decomposed and sent to middleware one by one. As a result, you should see redux-logger output actionA and actionB separately.

If your middleware also generates batch actions, you will need to add another middleware after it to decompose it:

import { createStore, applyMiddleware, compose } from 'redux';
import { batch, createAction } from 'redux-batch-actions-enhancer';
import promise from 'redux-promise';
import createLogger from 'redux-logger';

const logger = createLogger();
const { enhancer, middleware } = batch();

const store = createStore(
    reducer,
    initialState,
    compose(enhancer, applyMiddleware(promise, middleware, logger)),
);

store.dispatch(new Promise(resolve => resolve(createAction(actionA, actionB))));

In the example above, redux-promise might generate new batch action. To ensure that it will be well handled by following middleware and reducers, the built-in middleware needs to be added after. This way, redux-logger can output actionA and actionB separately.

Notice that both enhancer and middleware should be from same batch() return, otherwise they might not share the same local state and cause unintentional issues.

Reason

When using redux, I personally prefer to create many "atom" actions, each represents a specific modification of state. However, in real world, a user's action might cause a combination of many "atom" actions. If all those "atom" actions are sent one by one, it will cause reducers to change state many times and cause subscribers to be triggered multiple times. Since all these "atom" actions come from one single user action, it might be more nature if subscriptions can be triggered only once.

There are planty of implementations in the field already. However, after some research, I found none of them fulfills all my requirements. Thus, instead, this repo is created.

The main difference between this repo and many others are:

1. this one not only combines actions together, but also triggers subscription only once, just as there is only one action being dispatched.

   This will be very helpful for all subscriptions, especially those who have high computational costs.

2. this one offers enhancer instead of reconstructing reducers directly

   A good reason to start with enhancer not reducer is that it will be easier for middlewares to handle. If batch actions are only handled in reducer, middlewares can only see a bunch of actions all in one. That might add extra works for middleware as it might need to look one by one inside, to know if any of the actions in it should be dealt with.

3. this one offers optional middleware in case any existing middleware generates batch actions as well.

   It is very common for middleware such as redux-promise or redux-thunk to generate new actions. If batch actions are generated inside middleware, extra works need to be done to ensure it still works. Also, this repo makes it opt-in, so that one can choose when to use it.

4. this one only garuantees that batch action will trigger subscriptions one time, nothing more nothing less.

   Some other repo makes options to use different functions to debounce. This might provide more powerful feature, but also makes it harder to use. Simplicity is prefered here.