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README.md

Redux Easy Async

Redux Easy Async makes handling asynchronous actions, such as API requests, simple, reliable, and powerful.

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Table of Contents

Overview

Redux is fantastic tool for managing application state but since actions, by their very nature, are synchronous, asynchronous requests (such as to APIs) can be more challenging. Standard approaches involve a lot of boilerplate, reinventing the wheel, and opportunity for error. For more info see: Motivation

Redux Easy Async provides a simple yet powerful approach for creating and tracking asynchronous actions. Features:

  • Create asynchronous actions (including associated constants for start, success, and fail) with a single call.
  • Create reducer(s) that automatically track the status of asynchronous actions, i.e. pending, completed. No more dispatching loading actions or storing isFetching state.
  • Optional configuration to parse API responses pre-reducer, conditionally make requests, prevent multiple requests, and more.
  • Makes all your dreams come true and turns you into the person you always wanted to be.

Installation

With NPM:

npm install redux-easy-async --save

or with Yarn:

yarn add redux-easy-async

Basic Usage

  1. Add the async middleware to wherever you create your redux store:

    // assuming have created and imported a root reducer:
    // e.g. import rootReducer from './reducers';
    import { createStore, applyMiddleware } from 'redux';
    import { createAsyncMiddleware } from 'redux-easy-async';
    
    const asyncMiddleware = createAsyncMiddleware();
    createStore(rootReducer, applyMiddleware(asyncMiddleware));
  2. Create an async action:

    import { createAsyncAction } from 'redux-easy-async';
    
    export const fetchUser = createAsyncAction('FETCH_USER', (id) => {
      return {
        makeRequest: () => fetch(`https://myapi.com/api/user/${id}`),
      };
    });
    // fetchUser is now a function that can be dispatched:
    //   const id = 1;
    //   dispatch(fetchUser(id))
    //   
    // but it also has constant attached for start, success, fail
    //   fetchUser.START_TYPE === "START_FETCH_USER"
    //   fetchUser.SUCCESS_TYPE === "SUCCESS_FETCH_USER"
    //   fetchUser.FAIL_TYPE === "FAIL_FETCH_USER"
  3. Handle the action in a reducer somewhere:

    const usersReducer = (state = {}, action) => {
      const { type, payload } = action;
      switch (type) {
        case fetchUser.SUCCESS_TYPE:
          // do something here on succcess
        case fetchUser.FAIL_TYPE:
          // do something here with fail
        default:
          return state;
      }
    };
  4. Dispatch the action somewhere in your app:

    dispatch(fetchUser(1));
  5. Profit!

Advanced Usage

Automatially track request status, show a loading spinner

  1. add a requests reducer that will track all async actions:

    import { createAsyncReducer } from 'redux-easy-async';
    // createAsyncReducer takes an array of async actions and returns
    // a reducer that tracks them
    const requestsReducer = createAsyncReducer([fetchPost]);
    // now you have a reducer with keys for each each action passed to it
    // {
    //  FETCH_USER: {
    //    hasPendingRequests: false,
    //    pendingRequests: [],
    //  }
    // }
  2. Add the requests reducer to your main reducer somewhere:

    import { combineReducers } from 'redux';
    
    const rootReducer = combineReducers({
      requests: requestsReducer,
      // ...the other reducers for your app here
    });
  3. Show loading spinner in a component somewhere:

    // assuming you have the state of the request store, e.g:
    //  const requests = store.getState().requests;
    //  -- or --
    //  const { requests } = this.props;
    //    
    const isLoading = requests.FETCH_USER.hasPendingRequests;
    return (
      <div>
        { isLoading && <div>Show a loading spinner</div> }
        { !isLoading && <div>Show user data</div> }
      </div>);

Working examples

The examples directory includes fully working examples which you can run locally and test out Redux Easy Async.

  1. Install dependencies for the example you want to try (with npm or yarn):

    > cd examples/basic
    > npm install (or yarn install)
  2. Start the server

    > npm start (or yarn start)
    
  3. Go to http://localhost:4001/ in your browser.

Motivation

API

createAsyncAction(type, fn, [options]) ⇒ function

Kind: global function
Returns: function - actionCreator

Param Type Default Description
type string | object can either be a string (e.g. "GET_POSTS") or a a constants object created with createAsyncConstants.
fn function action creator function that returns an object with action configuration. See example below for configuration options. Only makeRequest is required.
[options] Object additional configuration options
[options.namespace] Object REDUX_EASY_ASYNC_NAMESPACE the middleware action type this action will be dispatched with. You most likely don't want to modify this unless for some reason you want multiple instances of async middleware.

Example (All configuration options for async action)

import { createAsyncAction } from 'redux-easy-async';

const myAction = createAsyncAction('MY_ACTION', () => {
  return {
    // function that makes the actual request. Return value must be a promise. In this example
    // `fetch()` returns a promise. **REQUIRED**
    makeRequest: () => fetch('/api/posts'),

    // *OPTIONAL*
    // additional meta that will be passed to the start, success, and fail actions if any. All
    // actions will have the following meta:
    //   - `actionName`
    //   - `asyncType`("start", "success", or "fail")
    //   - `requestStartTime`
    //   - `asyncID`: an unique id for each request
    // Success and fail actions will additionally have:
    //   - `requestDuration`
    //   - `resp`: the raw api response. Because of the nature of the promises errors that
    //     cause the makeRequest promise to be rejected will also get caught here as `resp`
    //     and cause a failed request action.
    meta = {},

    // function that takes your redux state and returns true or false whether to proceed with
    // the request. For example: checking if there is already a similar request in progress or
    // the requested data is already cached. *OPTIONAL*
    shouldMakeRequest = (state) => true,

    // `parseStart`, `parseSuccess`, and `parseSuccess` can be useful if you want to modify
    // raw API responses, errors, etc. before passing them to your reducer. The return value
    // of each becomes the payload for start, success, and fail actions. By default response
    // will not be modified.
    //
    // the return value of `parseStart` becomes the payload for the start action. *OPTIONAL*
    parseStart = () => null,
    // the return value of `parseSuccess` becomes the payload for the success action. *OPTIONAL*
    parseSuccess = resp => resp,
    // the return value of `parseFail` becomes the payload for the fail action. *OPTIONAL*
    parseFail = resp => resp,
  }

})

createAsyncConstants(type) ⇒ object

Creates an object with constant keys NAME, START_TYPE, SUCCESS_TYPE, FAIL_TYPE in the format that createAsyncAction, createAsyncReducer, and createAsyncReducer accept. Note: this is an extra optional step for those that prefer to separate action creator definitions from constants. If you don't know/case then just createSingleAsyncAction.

Kind: global function
Returns: object - returns an object with keys: NAME, START_TYPE, SUCCESS_TYPE, and FAIL_TYPE

Param Type Description
type string the base name for this constant, e.g. "GET_USER"

Example

const GET_USER = createAsyncConstants('GET_USER');
// {
//   NAME: 'GET_USER', // general name for action
//   START_TYPE: 'START_GET_USER', // start type of the this async action
//   SUCCESS_TYPE: 'SUCCESS_GET_USER', // success type of the this async action
//   FAIL_TYPE: 'FAIL_GET_USER' // fail type of the this async action
// }

createAsyncMiddleware(options) ⇒ function

Creates an instance of middleware necessary to handle dispatched async actions created with createAsyncAction.

Kind: global function
Returns: function - redux middleware for handling async actions

Param Type Default Description
options object options to create middleware with.
[options.requestOptions] object {} options that will be passed to all action's makeRequest functions: e.g. makeRequest(state, requestOptions).
[options.namespace] string "REDUX_EASY_ASYNC_NAMESPACE" the action type the middleware will listen for. You most likely don't want to modify this unless for some reason you want multiple instances of async middleware.

Example

import { createAsyncMiddleware } from 'redux-easy-async';
const asyncMiddleware = createAsyncMiddleware();

...

// Now add to your middlewares whereever your store is created.
// Typically this looks something like:
// const middlewares = [asyncMiddleware, ...other middlewares]

createAsyncReducer(types) ⇒ function

Creates a requests reducer that automatically tracks the status of one or more async actions created with createAsyncAction. As you dispatch async actions this reducer will automatically update with number of requests, request meta for each, a boolean for whether any requests are currently pending for this request.

Kind: global function
Returns: function - Redux reducer automatically tracking the async action(s)

Param Type Description
types Array | String | Object | function one or more async actions to track. Either a single instance or an array of one or more of the following: a string (e.g. `"GET_POSTS"``), a constants object created with createAsyncConstants, or an async action created with createAsyncAction. Typically you will want to pass an array of actions to track all async actions for your application in one place.

Example

import { createAsyncAction, createAsyncConstants } from '`redux-easy-async';

// Types can async action, constants object, or string:

// string constant
const FETCH_POSTS = 'FETCH_POSTS';

// async action
export const fetchUser = createAsyncAction('FETCH_USER', (id) => {
  return {
    makeRequest: () => fetch(`https://myapi.com/api/user/${id}`),
  };
});

// async constant
const fetchComments = createAsyncConstants('FETCH_COMMENTS');

// now we can create a reducer from the action or constants we've defined
const requestsReducer = createAsyncReducer([FETCH_POSTS, fetchUser, fetchComments]);

// Now `requestsReducer` is reducer that automatically tracks each of the asynchronous action
// types. It's state looks something like this to start:
// {
//   {
//    FETCH_POSTS: {
//      hasPendingRequests: false,
//      pendingRequests: [],
//   },
//   {
//    FETCH_USER: {
//      hasPendingRequests: false,
//      pendingRequests: [],
//   }
//   {
//    FETCH_COMMENTS: {
//      hasPendingRequests: false,
//      pendingRequests: [],
//   }
// }

Meta

Author: Evan Hobbs - NerdWallet

License: MIT - LICENSE for more information.

Todo

  • images/logo
  • finish Motivation section.
  • add error logging in middleware?
  • add more complicated example
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