Solving the One Fetch Request Creates Many GET Requests Dilemma in React

Описание: Discover how to handle asynchronous `fetch` calls in React effectively to avoid multiple server requests. Learn a simplified solution for your application.
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This video is based on the question https://stackoverflow.com/q/69922583/ asked by the user 'Tallented-Code-bot' ( https://stackoverflow.com/u/15514088/ ) and on the answer https://stackoverflow.com/a/69922649/ provided by the user 'testing_22' ( https://stackoverflow.com/u/12096922/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Fetch Request Problem in React

As developers, we often rely on fetch requests to retrieve data from APIs during our application's lifecycle. However, there is a frustrating issue some encounter — a single fetch request unexpectedly results in multiple GET requests being sent to the server. This can lead to performance issues and unnecessary load on the server, especially when we only expect to retrieve data once. In this guide, we’ll explore this problem in-depth, breaking it down using a real-world example from a React application.

The Problem Explained

In the given code snippet, a React component uses useEffect to make an API call when the component mounts. The expectation is simple: one fetch request should return the necessary data without additional requests being generated. However, the user noticed that not only is the data being fetched, but also more than ten requests are being fired to the server. Let’s break down the code provided to understand why this is happening.

Code Snippet

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Observations

The console.log statements for "Fetching data" and "Getting json from response" only trigger once, as expected.

Multiple GET requests, however, show up in both the server logs and browser network tools.

Understanding Asynchronous Behavior

The core issue stems from misunderstanding how fetch works in conjunction with React’s useEffect. The fetch call is asynchronous which means that it may not behave the way you expect it without proper handling. After thorough investigation, it is evident that the component might be re-rendering multiple times for other reasons (for example, state changes in its parent component).

Resolving the Problem: Using Asynchronous Functions in useEffect

A common solution to avoid the unwanted behavior of multiple fetch calls is to properly handle asynchronous data fetching within the useEffect hook. While you might be tempted to make your useEffect callback function async, it will not work directly because hooks do not support returning Promises. Instead, you should define an asynchronous function inside the useEffect callback like this:

Updated Code Implementation

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Key Changes Explained

Define an Async Function: The retrieveData function is defined within the useEffect. This allows it to use await to handle the fetch call properly.

Await Fetch: Use await to pause the code’s execution until the fetch completes, ensuring that the data is downloaded before moving on and executing setTutorials.

Maintain the Dependency Array: The empty dependency array [] ensures that the effect runs only once when the component mounts, thus avoiding any unintended multiple calls.

Conclusion

By following the corrected approach to handle fetch calls in React, you can prevent issues related to multiple GET requests being sent to the server. Always remember to be cautious with asynchronous operations and double-check your dependencies within the useEffect hook.

With these steps, you’ll improve your application’s performance and maintain a cleaner codebase. Happy coding!