Dynamically load redux reducers and redux-saga sagas as needed, instead of loading them all upfront. This has some nice benefits, such as avoiding having to manage a big global list of reducers and sagas. It also allows more effective use of code-splitting. See motivation. As used by react-boilerplate.

Getting Started

``bash
npm install redux-injectors # (or yarn add redux-injectors)
`

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The redux store needs to be configured to allow this library to work. The library exports a store enhancer that can be passed to the createStore function.
`js
import { createStore } from "redux";
import { createInjectorsEnhancer } from "redux-injectors";

const store = createStore(
createReducer(),
initialState,
createInjectorsEnhancer({
createReducer,
runSaga,
})
)
`

Note the createInjectorsEnhancer function takes two options. createReducer should be a function that when called will return the root reducer. It's passed the injected reducers as an object of key-reducer pairs.

`js
function createReducer(injectedReducers = {}) {
const rootReducer = combineReducers({
...injectedReducers,
// other non-injected reducers can go here...
});

return rootReducer
}
`

runSaga should usually be sagaMiddleware.run.

`js
const runSaga = sagaMiddleware.run;
`

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If you're using redux devtools, it's important to set shouldHotReload to false. This is because otherwise, redux devtools will re-dispatch previous actions when reducers are injected, causing unexpected behavior.

If using redux-toolkit:
`js
const store = configureStore({
devTools: {
shouldHotReload: false
}
})
`

If not using redux-toolkit:
`js
import { composeWithDevTools } from 'redux-devtools-extension';

const composeEnhancers = composeWithDevTools({
shouldHotReload: false
});

const store = createStore(reducer, composeEnhancers(
...
));
`

Unfortunately this causes a separate issue where the action history is cleared when a reducer is injected, but it's still strongly recommended to set shouldHotReload to false. There's an open issue in the redux-devtools repo about this.

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After setting up the store, you will be able to start injecting reducers and sagas.
`js
import { compose } from "redux";
import { injectReducer, injectSaga } from "redux-injectors";

class BooksManager extends React.PureComponent {
render() {
return null;
}
}

export default compose(
injectReducer({ key: "books", reducer: booksReducer }),
injectSaga({ key: "books", saga: booksSaga })
)(BooksManager);

`

Or, using hooks:
`js
import { useInjectReducer, useInjectSaga } from "redux-injectors";

export default function BooksManager() {
useInjectReducer({ key: "books", reducer: booksReducer });
useInjectSaga({ key: "books", saga: booksSaga });

return null;
}
`

Note: while the above usage should work in most cases, you might find your reducers/sagas aren't being injected in time to receive an action. This can happen, for example, if you dispatch an action inside a useLayoutEffect instead of a useEffect. In that case, useInjectReducer and useInjectSaga return boolean flags that are true once the reducers/sagas have finished injecting. You can check these before rendering children that depend on these reducers/sagas being injected.

`js
import { useInjectReducer, useInjectSaga } from "redux-injectors";

export default function BooksManager(props) {
const reducerInjected = useInjectReducer({ key: "books", reducer: booksReducer });
const sagaInjected = useInjectSaga({ key: "books", saga: booksSaga });

if (!reducerInjected || !sagaInjected) {
return null;
}

return (
<>
{props.children}

);
}
``

Documentation

See the API reference
Or the example

Motivation

There's a few reasons why you might not want to load all your reducers and sagas upfront:
1. You don't need all the reducers and sagas for every page. This library lets you only load the reducers/sagas that are needed for the page being viewed. This speeds up the page load time because you can take advantage of code-splitting. This is also good for performance after the page has loaded, because fewer reducers and sagas are running.
2. You don't want to have to manage a big list of reducers/sagas. This library lets components inject their own reducers/sagas, so you don't need to worry about adding reducers/sagas to a global list.