Simple reducer for `redux-promise-middleware`

Usage no npm install needed!

<script type="module">
  import reduxPromiseReducer from '';



Provides an action creator and reducer that easily integrates with redux-promise-middleware.


npm install redux-promise-reducer --save


1. Setup the redux-promise-middleware

Setup your store with the middleware to make sure it handles the actions you'll create for resolving promises.

2. Create the reducer that will handle all the actions created by the middleware.

You can either use the default reducing functions for the PENDING, FULFILLED and REJECTED actions (see below for details):

import { promiseReducer } from 'redux-promise-reducer';
const myreducer = promiseReducer();

or you can customize how your reducer calculated the next state for each update in the promise state:

const myreducer = promiseReducer({
    // here we choose not to change the default reducer for PENDING
    fulfilledReducer: () => 'ok', 
    rejectedReducer: () => 'awww man!'

3. Make sure your store uses your new reducer

Here we use redux.combineReducers to make sure all your promises reside under a specific property (data in this case) in your state:

import { combineReducers } from 'redux'
const rootReducer = combineReducers({
  data: promiseReducer,
  ... // other reducers heres
// create the store using `rootReducer`

4. Dispatch actions using the supplied action creator

The action creator createPromiseAction creates actions that will be handled by redux-promise-middleware. The middleware will immediately invoke a PENDING action; it will also make sure that the promise embedded in the action is either FULFILLED or REJECTED, and will invoke new actions when that happens. These new actions will then be reduced by the reducer we created earlier.

Every action created by this creator get prefixed with RPR. Also, the reducer only handles actions that have this prefix (along with some other requirements, like terminating with either PENDING|FULFILLED|REJECTED). This currently hard-coded.

Some examples:

  • create an action with type RPR_RESOLVE_PROPNAME (the action name is being inferred from the property name - note it adds RESOLVE_ to it). Data will be stored in the state under a property named propname
import { createPromiseAction } from 'redux-promise-reducer';
const promise = Promise.resolve('ok');
const action = createPromiseAction({parameter: 'propname', promise});
  • you can specify the action name instead. This creates an action with type RPR_JUST_DO_IT
const promise = Promise.resolve('ok');
const action = createPromiseAction({parameter: 'propname', actionName: 'JUST_DO_IT', promise});

Also note the action names are always in caps.

The default reducing functions

You create your reducer by invoking promiseReducer. This functions accepts an object, which holds functions that define how your state is modified in each state of the promise:

    // function that will determine the next state when a PENDING action is dispatched by the middleware
    pendingReducer: (state, action) => ...  
    fulfilledReducer: (state, action) => ...  
    rejectedReducer: (state, action) => ...  

You can however omit the whole object, or at least some of its parameters. In that case the default reducing functions will be used, which will produce the following states (note that propname is the name of the property that was specified when creating the action with createPromiseAction:

For the PENDING state:

propname: {
    pending: true,
    error: false,
    ready: false

For the FULFILLED state:

propname: {
    pending: false,
    error: false,
    ready: true,
    data: ... // result of the promise

For the REJECTED state:

propname: {
    pending: true,
    error: true,
    ready: false