redux-promise-middleware-actions
Create Redux actions with a type and payload in a standardized way. Inspired by redux-actions but simpler and with special support for asynchronous actions (promises).
Has no dependencies and is tiny (~680 bytes gzipped). First class TypeScript support.
Works with redux-promise-middleware to handle asynchronous actions by dispatching pending, fulfilled and rejected events based on the state of the input promise.
Goals of this library:
- Reference action creators directly - no need to maintain an action type enum/list
- Automatically generate actions for pending, fulfilled and rejected outcomes of a promise payload
- Have statically typed access to all action types - no need to manually add a type suffix like "_PENDING"
- TypeScript support so asynchronous actions can't be confused for normal synchronous actions
Note: If you are using TypeScript this library requires TypeScript 3. For TypeScript 2 use version 1 of this library.
Installation
You need to install this library as well as redux-promise-middleware.
npm install redux-promise-middleware-actions redux-promise-middleware
Include redux-promise-middleware when you create your store:
import promiseMiddleware from 'redux-promise-middleware';
composeStoreWithMiddleware = applyMiddleware(
promiseMiddleware,
)(createStore);NOTE: This library is not yet compatible with the promiseTypeSuffixes option of redux-promise-middleware
Usage
Synchronous action
Synchronous actions works exactly like redux-actions. You supply a function that returns whatever payload the action should have (if any).
import { createAction } from 'redux-promise-middleware-actions';
export const foo = createAction('FOO', (num) => num);
dispatch(foo(5)); // { type: 'FOO', payload: 5 }When handling the action in a reducer, you simply cast the action function to a string to return the type. This ensures type safety (no spelling errors) and you can use code navigation to find all uses of an action.
const fooType = foo.toString(); // 'FOO'Asynchronous action
When you create an asynchronous action you need to return a promise payload. If your action is called FOO the following events will be dispatched:
FOO_PENDINGis dispatched immediatelyFOO_FULFILLEDis dispatched when the promise is resolved- ... or
FOO_REJECTEDis dispatched instead if the promise is rejected
- ... or
import { createAsyncAction } from 'redux-promise-middleware-actions';
export const fetchData = createAsyncAction('FETCH_DATA', async () => {
const res = await fetch(...);
return res.json();
});
dispatch(fetchData()); // { type: 'FETCH_DATA_PENDING' }An async action function has three properties to access the possible outcome actions: pending, fulfilled and rejected. You can dispatch them directly (in tests etc.):
dispatch(fetchData.pending()); // { type: 'FETCH_DATA_PENDING' }
dispacth(fetchData.fulfilled(payload)); // { type: 'FETCH_DATA_FULFILLED', payload: ... }
dispacth(fetchData.rejected(err)); // { type: 'FETCH_DATA_REJECTED', payload: err, error: true }But normally you only need them when you are writing reducers:
case fetchData.pending.toString(): // 'FETCH_DATA_PENDING'
case fetchData.fulfilled.toString(): // 'FETCH_DATA_FULFILLED'
case fetchData.rejected.toString(): // 'FETCH_DATA_REJECTED'Note that if you try and use the base function in a reducer, an error will be thrown to ensure you are not listening for an action that will never happen:
case fetchData.toString(): // throws an errorReducer
To create a type safe reducer, createReducer takes a list of handlers that accept one or more actions and returns the new state. You can use it with both synchronous and asynchronous action creators.
createReducer(defaultState, handlerMapsCreator)
import { createAsyncAction, createReducer } from 'redux-promise-middleware-actions';
const fetchData = createAsyncAction('GET', () => fetch(...));
const defaultState = {};
const reducer = createReducer(defaultState, (handleAction) => [
handleAction(fetchData.pending, (state) => ({ ...state, pending: true })),
handleAction(fetchData.fulfilled, (state, { payload }) => ({ ...state, pending: false, data: payload })),
handleAction(fetchData.rejected, (state, { payload }) => ({ ...state, pending: false, error: payload })),
]);
reducer(undefined, fetchData()); // { pending: true, data: ..., error: ... }asyncReducer(asyncActionCreator)
It can get tedious writing the same reducer for every single async action so we've included a simple reducer that does the same as the example above:
import { asyncReducer } from 'redux-promise-middleware-actions';
const fetchData = createAsyncAction('GET', () => fetch(...));
const fetchReducer = asyncReducer(fetchData);
fetchReducer() // { data?: Payload, error?: Error, pending?: boolean }You can also combine it with an existing reducer:
export default (state, action) => {
const newState = fetchReducer(state, action);
switch (action.type) {
case 'SOME_OTHER_ACTION':
return { ... };
default:
return newState;
}
};Metadata
You can add metadata to any action by supplying an additional metadata creator function. The metadata creator will receive the same arguments as the payload creator:
createAction(type, payloadCreator, metadataCreator)
const foo = createAction(
'FOO',
(num) => num,
(num) => num + num
);
dispatch(foo(5)); // { type: 'FOO', meta: 10, payload: 5 }createAsyncAction(type, payloadCreator, metadataCreator)
const fetchData = createAsyncAction(
'FETCH_DATA',
(n: number) => fetch(...),
(n: number) => ({ n })
);
dispatch(fetchData(42));
// { type: 'FETCH_DATA_PENDING', meta: { n: 42 } }
// { type: 'FETCH_DATA_FULFILLED', meta: { n: 42 }, payload: Promise<...> }
// { type: 'FETCH_DATA_REJECTED', meta: { n: 42 }, payload: Error(...) }Custome Type Delimiters
You can specify a different type delimiter for your async actions:
createAsyncAction(type, payloadCreator, metadataCreator, options)
const foo = createAsyncAction(
'FETCH_DATA',
(n: number) => fetch(num),
undefined,
{ promiseTypeDelimiter: '/' }
);
dispatch(foo());
// { type: 'FETCH_DATA/PENDING' }
// { type: 'FETCH_DATA/FULFILLED', payload: ... }
// { type: 'FETCH_DATA/REJECTED', payload: ... }Acknowledgements
Thanks to Deox for a lot of inspiration for the TypeScript types.
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