@cromwellian/redux-promise-middleware-actions
v2.1.1
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Redux action creator for making async actions with redux-promise-middleware
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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);
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 = String(foo); // '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_PENDING
is dispatched immediatelyFOO_FULFILLED
is dispatched when the promise is resolved- ... or
FOO_REJECTED
is 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 String(fetchData.pending): // 'FETCH_DATA_PENDING'
case String(fetchData.fulfilled): // 'FETCH_DATA_FULFILLED'
case String(fetchData.rejected): // '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 String(fetchData): // throws an error
Async reducer
You can now handle the different events in your reducer by referencing the possible outcome states:
import { fetchData } from './actions';
export default (state, action) => {
switch (action.type) {
case String(fetchData.pending):
return {
...state,
pending: true,
};
case String(fetchData.fulfilled):
return {
...state,
data: action.payload,
error: undefined,
pending: false,
};
case String(fetchData.rejected):
return {
...state,
error: action.payload,
pending: false,
};
default:
return state;
}
};
Async reducer helper
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';
import { fetchData } from './actions';
export default asyncReducer(fetchData);
You can also combine it with an existing reducer:
import { asyncReducer } from 'redux-promise-middleware-actions';
import { fetchData } from './actions';
const fetchReducer = asyncReducer(fetchData);
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)
export const foo = createAction(
'FOO',
(num) => num,
(num) => num + num
);
dispatch(foo(5)); // { type: 'FOO', meta: 10, payload: 5 }
createAsyncAction(type, payloadCreator, metadataCreator)
export 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(...) }