How to use Redux Saga?

Redux Saga is a middleware library used to handle side effects in your Redux app, such as asynchronous actions like data fetching, caching, etc.

To use Redux Saga, follow these steps:

Step 1: Install Redux Saga
The first step is to install Redux Saga as a part of your project dependencies. You can add it to your project using npm or yarn.

For npm:

npm install —save redux-saga

For yarn:

yarn add redux-saga

Step 2: Import and Connect Redux Saga Middleware
The next step is to import the redux-saga dependencies in your Redux store and then to create a saga middleware.

import createSagaMiddleware from ‘redux-saga’; const sagaMiddleware = createSagaMiddleware();

Include the sagaMiddleware to your Redux app middlewares list. Redux applyMiddlewares will be used for redux-saga as middleware.

import { createStore, applyMiddleware } from ‘redux’; const store = createStore( reducer, applyMiddleware(sagaMiddleware) );

Step 3: Write Sagas
Sagas are like separate threads in your application that’s solely responsible for side effects. You write sagas in JavaScript generator functions (function) and use `yield` keyword to pause and resume their execution.

import { call, put, takeEvery } from ‘redux-saga/effects’; // Import from ‘redux-saga/effects’ // Worker Saga function\* fetchUser(action) { try { const user = yield call(api.fetchUser, action.payload.userId); // Call fetchUser API yield put({type: ‘USER_FETCH_SUCCEEDED’, user: user}); // Dispatch an action when API call succeeds } catch (error) { yield put({type: ‘USER_FETCH_FAILED’, message: error.message}); // Dispatch an action when API call fails } } // Watcher Saga function\* watchFetchUser() { yield takeEvery(‘USER_FETCH_REQUESTED’, fetchUser); // “takeEvery” listens for ‘USER_FETCH_REQUESTED’ action dispatched, then call the fetchUser saga }

Step 4: Run Sagas
The saga middleware provides a method called `run` that serves to run your Saga. To block the Saga Middleware until all the Sagas have been started, you will invoke the `run` method.

sagaMiddleware.run(watchFetchUser); // can include more sagas separated by commas

And you’re done! You have implemented and used Redux Saga to handle the side effects of your Redux application.

Remember that this is just a very basic introduction to Redux Saga. It’s a very powerful tool with a lot more features like sagas composition, error handling, saga testing, cancellation, etc.