How to Fetch Data With Redux-Saga in a React Application

React and Redux are popular web development tools for managing state and developing dynamic user interfaces.

Accessing information can be difficult and time-consuming, especially when dealing with asynchronous events. Redux-Saga, an easy-to-use middleware package that manages asynchronous activities, can simplify this process.

Learn how React to build an application that retrieves data from Redux-Saga.

Understanding Redux-Saga

Redux-Saga is a middleware package that makes it simpler to manage and test side effects like browser storage access and asynchronous API requests. Using generator functions makes asynchronous code appear synchronous, making it easier to reason about and debug.

Redux-Saga works by looking for specific Redux actions and triggering Sagas, which are side effect generator functions. Sagas can run asynchronous operations, such as obtaining data from an API, and then dispatch a fresh Redux action to update the state.

Take the example of using Redux-Saga to manage asynchronous API calls. Start by creating a Redux action that initiates the data-gathering procedure:

        export const FETCH_DATA = 'FETCH_DATA';

export const fetchData = (params) => ({
  type: FETCH_DATA,
  payload: params,
});

The action’s payload, FETCH_DATA, includes any essential parameters, like the API endpoint and request parameters.

Next, define a Saga that listens for the FETCH_DATA activity and does the data gathering:

        import { call, put, takeLatest } from 'redux-saga/effects';
import axios from 'axios';

export function* fetchDataSaga(action) {
  try {
    const response = yield call(axios.get, action.payload.endpoint, {
      params: action.payload.params,
    });

    yield put({ type: 'FETCH_DATA_SUCCESS', payload: response.data });
  } catch (error) {
    yield put({ type: 'FETCH_DATA_ERROR', payload: error });
  }
}

export function* watchFetchData() {
  yield takeLatest(FETCH_DATA, fetchDataSaga);
}

This Saga makes an API call to the axios library using the call effect. It then sends the fetched data as a new Redux action payload with the type FETCH_DATA_SUCCESS. If an error occurs, it sends out a new Redux action with the error object as the payload and a type of FETCH_DATA_ERROR.

Finally, you need to register the Saga with the Redux store using the redux-saga middleware:

        import { applyMiddleware, createStore } from 'redux';
import createSagaMiddleware from 'redux-saga';
import rootReducer from './reducers';

const sagaMiddleware = createSagaMiddleware();
const store = createStore(rootReducer, applyMiddleware(sagaMiddleware));
sagaMiddleware.run(watchFetchData);

By registering the watchFetchData Saga with the new instance middleware, this code creates another redux-saga. The middleware is set up on the Redux store using ApplyMiddleware.

Redux-Saga, in general, provides a strong and versatile approach for managing asynchronous activities within React's Redux applications. You may streamline data fetching and generate easier code to test, maintain, and update by using Sagas to control code bugs.

Common Data Fetching Issues in React Applications

There are a few difficulties that developers frequently find while using React's data fetching. Here are a few examples:

Managing asynchronous actions: This is information supplied by a programming interface that keeps track of nonconcurrent operations without interfering with the user interface (UI). Working with several API requests or data that is reliant on other data might make this tough.
Handling errors: API calls can fail, and it is vital that you handle these errors correctly. This includes providing error messages to the user and allowing them to resubmit the request.
Updating the Redux store: You should save information acquired from an API in the Redux store so other components can access it. It is crucial to update the store without interfering with or corrupting already existing data.

How to Use Redux-Saga for Data Fetching in React

Using Redux-Saga for data fetching allows you to separate the logic for making API calls and dealing with the response from your React components. As a result, you can focus on rendering the data and reacting to user interactions while the Sagas handle asynchronous data retrieval and error management.

You need to register the watchFetchData Saga with the Redux-Saga middleware to use the Sagas in our Redux store:

        // src/store.js
import { createStore, applyMiddleware } from 'redux';
import createSagaMiddleware from 'redux-saga';
import rootReducer from './reducers';
import { watchFetchData } from './sagas/dataSaga';

const sagaMiddleware = createSagaMiddleware();
const store = createStore(rootReducer, applyMiddleware(sagaMiddleware));
sagaMiddleware.run(watchFetchData);

export default store;

This code registers the sagaMiddleware with the Redux store using the applyMiddleware function and the createSagaMiddleware method of the redux-saga package. Then, using the run method, it executes the watchFetchData Saga.

Your Redux-Saga setup is complete now that each component is in place. The Saga uses the fetchDataApi function to fetch the data when your React component sends the FETCH_DATA_REQUEST action. If the scheduled data fetch is successful, it dispatches another activity with the fetched data. If there is an error, it sends a new action with the error object.

        // src/components/DataComponent.js

import React, { useEffect } from 'react';
import { useDispatch, useSelector } from 'react-redux';
import { fetchDataRequest } from '../actions/dataActions';

const DataComponent = () => {
  const dispatch = useDispatch();
  const { data, isLoading, error } = useSelector((state) => state.data);

  useEffect(() => {
    dispatch(fetchDataRequest({ param1: 'value1', param2: 'value2' }));
  }, [dispatch]);

  if (isLoading) {
    return <div>Loading...</div>;
  }

  if (error) {
    return <div>Error: {error.message}</div>;
  }

  return (
    <div>
      {data.map((item) => (
        <div key={item.id}>{item.name}</div>
      ))}
    </div>
  );
};

export default DataComponent;

In the example above, you use the useSelector hook in your React component to get the data, isLoading, and error values from the Redux store. You additionally dispatch the FETCH_DATA_REQUEST action using the useEffect() hook when the component mounts. You render the data, loading message, or error message depending on the data values, isLoading, and error.

By leveraging Redux-Saga for data fetching, managing asynchronous API requests in a React application may be significantly streamlined. You can create more maintainable and modular code by isolating the API call logic from your components and managing the asynchronous flow in Sagas.

Best Practices for Using Redux-Saga for Data Fetching

Follow these best practices while using Redux-Saga for data fetching:

Use distinct Sagas for each data fetching operation. It is advisable to separate a Saga for each data fetching process rather than including all the logic into a single Saga. Maintaining and altering the code is simpler since you can immediately find the relevant Sagas for certain activities.
Use Redux-Saga's built-in error handling. You can use Redux-Saga's try/catch block to handle errors automatically. This allows us to manage failures centrally and provide users with uniform error messages.
Use cancelable sagas for better performance. When you use a React component, it can trigger many API calls. Race situations and unnecessary Programming interface calls may result from this API trigger. By canceling any ongoing API calls when you make a new request, you can prevent this.
Use the most current data. When making several API requests for the same data, it is crucial to ensure that they use the most recent data. Using the latest effect, Redux-Saga helps you achieve this. The effect ensures that you’re using the latest or most recent API calls and cancels any pending API requests for the same data.
Use a separate file for sagas. You should keep the Sagas separate from the Redux store file. As a result, your Sagas will be easier to control and test.

Fetch Data With Redux-Saga

Redux-Saga offers a reliable and flexible method for handling asynchronous tasks in React applications. Using Sagas, you can create more robust, testable, and flexible code that separates concerns.

Data fetching can be a difficult and error-prone operation, but you can make it simpler with the help of Redux-Saga. Redux-Saga improves user experience by allowing you to reliably and predictably manage many asynchronous processes.

Due to its many benefits and features, Redux-Saga is a fantastic addition to your collection of React development tools.