Managing API State and Global Data

1. Introduction

In React applications, managing API state is a critical task. As your app grows in complexity, it becomes increasingly important to handle API data consistently and efficiently across various components. Without a structured approach to managing state, data fetching can become repetitive, hard to maintain, and prone to errors.

In this post, we’ll explore different strategies for managing global API state in React applications, focusing on:

Redux Toolkit Query (RTK Query)
Context API
Combining API data across components

We’ll also examine how to optimize data fetching, state management, and synchronization to create scalable and efficient applications.

2. What Is Global State in React?

In React, global state refers to state that is shared across multiple components in your application. Rather than having each component manage its own local state, you can centralize state management, enabling components to access and update shared data.

For example, an app that displays a user’s profile might need to fetch the profile data once and share it across several components (e.g., ProfileDetails, ProfileSettings, and FriendsList). Managing the profile data as global state makes it easier to synchronize and update across multiple components.

Global state is particularly useful for:

API data that is needed by many parts of your application.
User authentication state, like whether the user is logged in or not.
Theme and UI preferences, like dark mode or language settings.

3. The Challenge of Managing API State in React

When working with APIs, especially in larger applications, there are several challenges:

Data synchronization: API data might need to be accessed by multiple components, making it difficult to manage when each component has its own copy of the data.
Re-fetching: If you’re not careful, you might end up fetching the same data multiple times, increasing the load on both your API and your app.
Performance: React’s re-rendering behavior can lead to performance bottlenecks when large amounts of data are updated unnecessarily.
Error handling: Managing loading, error, and success states across multiple components can become cumbersome if not handled properly.

4. Managing API State Locally in React

In smaller apps, or when API data is only used in a single component, local state can suffice. The useState and useEffect hooks are perfect for this purpose.

Here’s a simple example of managing API state locally:

import React, { useState, useEffect } from 'react';

function ProductList() {
  const [products, setProducts] = useState([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState('');

  useEffect(() => {
async function fetchProducts() {
  try {
    const res = await fetch('https://api.example.com/products');
    if (!res.ok) throw new Error('Failed to fetch products');
    const data = await res.json();
    setProducts(data);
  } catch (err) {
    setError(err.message);
  } finally {
    setLoading(false);
  }
}
fetchProducts();  }, []);

  if (loading) return <p>Loading...</p>;
  if (error) return <p>Error: {error}</p>;

  return (
&lt;ul&gt;
  {products.map(product =&gt; &lt;li key={product.id}&gt;{product.name}&lt;/li&gt;)}
&lt;/ul&gt;  );
}

This example handles the fetching of data, manages loading and error states, and updates the component’s UI.
However, this approach only works well when the data is used in one component.

5. Global State Management Solutions in React

As your app grows, it becomes more challenging to manage state locally in each component. This is where global state management solutions come in. React offers several ways to manage global state:

Redux Toolkit Query (RTK Query)
React Context API
Custom hooks for global state

Let’s explore each solution in more detail.

6. Using Redux Toolkit Query (RTK Query) for API State

Redux Toolkit Query is a powerful data-fetching and caching tool integrated into Redux. It’s designed to simplify data fetching, state management, and synchronization in large-scale applications.

a. Why Choose Redux Toolkit Query?

Simplified API integration: RTK Query provides pre-built hooks to manage API calls, so you don’t have to write reducers or actions for each endpoint.
Automatic caching: Data fetched through RTK Query is cached automatically, reducing the need to re-fetch the same data.
Optimistic updates and pagination: RTK Query provides support for advanced features like optimistic updates and pagination.
Efficient state updates: By using Redux, RTK Query minimizes unnecessary re-renders of your components.

b. Setting Up RTK Query

Start by installing Redux Toolkit and configuring the store:

npm install @reduxjs/toolkit react-redux

Create a services/products.js file for your API slice:

import { createApi, fetchBaseQuery } from '@reduxjs/toolkit/query/react';

export const productsApi = createApi({
  reducerPath: 'productsApi',
  baseQuery: fetchBaseQuery({ baseUrl: 'https://api.example.com' }),
  endpoints: (builder) => ({
getProducts: builder.query({
  query: () =&gt; 'products',
}),  }),
});

export const { useGetProductsQuery } = productsApi;

Next, integrate RTK Query into your Redux store:

import { configureStore } from '@reduxjs/toolkit';
import { productsApi } from './services/products';

const store = configureStore({
  reducer: {
&#91;productsApi.reducerPath]: productsApi.reducer,  },
  middleware: (getDefaultMiddleware) =>
getDefaultMiddleware().concat(productsApi.middleware),});

export default store;

Now you can access the API state in your components using the auto-generated useGetProductsQuery hook:

import React from 'react';
import { useGetProductsQuery } from './services/products';

function ProductList() {
  const { data: products, error, isLoading } = useGetProductsQuery();

  if (isLoading) return <p>Loading...</p>;
  if (error) return <p>Error: {error.message}</p>;

  return (
&lt;ul&gt;
  {products.map(product =&gt; &lt;li key={product.id}&gt;{product.name}&lt;/li&gt;)}
&lt;/ul&gt;  );
}

export default ProductList;

c. Benefits of RTK Query

Automatic caching: You don’t need to manage caching manually.
Simplified state management: RTK Query automatically handles loading, error, and success states.
Global state sync: Any component using the useGetProductsQuery hook will always have access to the latest state.

7. Using the Context API for Global State

The Context API is another solution for managing global state in React, especially for simpler or medium-sized applications. It allows you to share state across your entire component tree without prop drilling.

a. Creating a Context for API Data

Let’s create a global context to manage products data:

import React, { createContext, useContext, useState, useEffect } from 'react';

const ProductsContext = createContext();

export function useProducts() {
  return useContext(ProductsContext);
}

export function ProductsProvider({ children }) {
  const [products, setProducts] = useState([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState('');

  useEffect(() => {
async function fetchProducts() {
  try {
    const res = await fetch('https://api.example.com/products');
    if (!res.ok) throw new Error('Failed to fetch products');
    const data = await res.json();
    setProducts(data);
  } catch (err) {
    setError(err.message);
  } finally {
    setLoading(false);
  }
}
fetchProducts();  }, []);

  return (
&lt;ProductsContext.Provider value={{ products, loading, error }}&gt;
  {children}
&lt;/ProductsContext.Provider&gt;  );
}

b. Using the Context in Components

Wrap your app with the ProductsProvider to make the global state accessible:

import React from 'react';
import { ProductsProvider } from './ProductsContext';
import ProductList from './ProductList';

function App() {
  return (
&lt;ProductsProvider&gt;
  &lt;ProductList /&gt;
&lt;/ProductsProvider&gt;  );
}

export default App;

Now, any component can access the global state:

import React from 'react';
import { useProducts } from './ProductsContext';

function ProductList() {
  const { products, loading, error } = useProducts();

  if (loading) return <p>Loading...</p>;
  if (error) return <p>Error: {error}</p>;

  return (
&lt;ul&gt;
  {products.map(product =&gt; &lt;li key={product.id}&gt;{product.name}&lt;/li&gt;)}
&lt;/ul&gt;  );
}

export default ProductList;

c. Benefits of the Context API

No external dependencies: The Context API is built into React, making it a great choice for simple state management.
Simple to set up: Setting up the Context API is straightforward and ideal for smaller apps or when you don’t