Part 81: Integrating Cart Items Data Fetching on the Cart Page

[Pages] Shopping Cart (Exercises)

[Pages] Shopping Cart (Exercises)

Displaying a user's shopping cart is an essential part of any e-commerce platform. With our new API route set up to return cart items, the next step is to integrate this functionality into the Cart page. In this blog post, we'll explore how to use React Query to fetch and display cart items data.

The Task

Our goal is to modify the Cart page to fetch cart items data using the newly created API route. We'll utilize React Query to handle data fetching, caching, and synchronization, ensuring that our application remains responsive and efficient.

Using React Query to Fetch Cart Items

Step 1: Setting Up the Cart Page

We'll start by modifying the CartPage component to fetch cart items data. We will use the useQuery hook from React Query to handle the data fetching process.

// File: pages/cart.js

import { useQuery } from 'react-query';
import Page from '../components/Page';
import { fetchJson } from '../lib/api';

function CartPage() {
  // Use React Query's useQuery hook to fetch cart items
  const query = useQuery('cartItems', () => fetchJson('/api/cart'));
  const cartItems = query.data;

  // Log the cart items data to the console for verification
  console.log('[CartPage] cartItems:', cartItems);

  return (
    <Page title="Cart">
      {/* Additional UI components to display cart items will be added here */}
    </Page>
  );
}

export default CartPage;

Step 2: Understanding the Code

1. React Query Integration: We utilize the useQuery hook to fetch data from the /api/cart endpoint. The first argument to useQuery is a unique key, 'cartItems', which helps React Query manage the cache for this specific query. The second argument is a function that performs the fetch operation using our fetchJson utility.

2. Data Access: The query.data property holds the fetched cart items data. We log this data to the console to verify that the expected array of cart items is being received.

3. Display Logic: While the current implementation only logs the data, we can extend this to display the cart items on the page. For now, the focus is on ensuring that data fetching is working correctly.

Step 3: Enhancements and Best Practices

• Loading Indicators: You can use the query.isLoading flag to display a loading indicator while the data is being fetched. This enhances the user experience by providing feedback during the fetch operation.

• Error Handling: Implement error handling using the query.isError flag to display error messages if the data fetch fails.

• Custom Hooks: For cleaner code, consider extracting the data fetching logic into a custom React hook. This encapsulates the logic and makes it reusable across different components.

Conclusion

By integrating React Query into our Cart page, we've successfully set up a mechanism to fetch and manage cart items data efficiently. This implementation is a crucial step towards building a dynamic and interactive shopping cart experience. As you further develop the cart page, consider adding features like loading indicators and error messages to enhance user interaction.

With this setup in place, you're well on your way to creating a seamless shopping experience for users. Stay tuned for future posts where we'll dive deeper into displaying and managing cart items on the frontend.