Understanding When to Fetch Data vs. Update State in React with UseEffect

A comprehensive guide on deciding when to fetch data and when to update state using React's useEffect. Learn best practices for managing state and ensuring data integrity with Axios.
---
This video is based on the question https://stackoverflow.com/q/65575346/ asked by the user 'Sinan Yaman' ( https://stackoverflow.com/u/12358693/ ) and on the answer https://stackoverflow.com/a/65575468/ provided by the user 'Dennis Vash' ( https://stackoverflow.com/u/7882470/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: When to fetch data and when to update state?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/licensing
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding When to Fetch Data vs. Update State in React with UseEffect

Working with data fetching and state management in React can lead to confusion, especially when deciding whether to fetch data again or simply update the local state. Let's explore a common scenario that many React developers face, and delve into the best practices for handling these cases effectively.

The Problem: Fetching Data and Updating State

Imagine you have a React component that fetches data from an API using Axios. This component retrieves an array of objects that a user can interact with. For example, here’s a JSON response you might receive:

[[See Video to Reveal this Text or Code Snippet]]

In this setup, when a user deletes an item from the list, you have a couple of options:

Update the state immediately using setData after the deletion.

Fetch the data again using useEffect after the deletion request is complete.

The intuition might be to rely on useEffect so that the component's data stays in sync with the server. However, there are better approaches available, especially in terms of performance and reliability.

The Solution: Best Practices for State Management

Handle Server Errors Gracefully

One critical issue to consider is what happens when a server error occurs. If the deletion fails after you've optimistically updated the state, your UI can quickly become out of sync with the actual server state. To prevent this, keep the following best practices in mind:

Use Middleware for State Updates

Rather than directly manipulating local state in the component, consider using a middleware that updates your application's state store.

For instance, instead of this pattern:

[[See Video to Reveal this Text or Code Snippet]]

You should ideally implement something like this:

[[See Video to Reveal this Text or Code Snippet]]

Avoid Duplicating State Management

As a rule of thumb, you should avoid duplicating state management. If you're fetching data and then also managing state in the component, you're dealing with two sources of truth, which can introduce bugs and inconsistencies.

Optimistic UI Updates

In situations where you want to enhance user experience with faster feedback, you can use optimistic UI updates. This means you can update your state right away and optimistically assume the server will confirm the change, as shown below:

[[See Video to Reveal this Text or Code Snippet]]

When to Fetch Data Again

Only consider fetching data again when:

You absolutely need the most current state from the server.

You want to ensure that the UI accurately reflects the server's data after a reliable response.

Conclusion

Deciding when to fetch data and when to update state is crucial for efficient data management in React. By adopting the best practices outlined in this post—such as handling server errors gracefully, avoiding duplicated state, and utilizing optimistic updates—you can create a more robust and reliable application.

Keeping your UI in sync with the server while using efficient state management techniques will lead to smoother user experiences and help prevent common pitfalls in React development. Happy coding!

Видео Understanding When to Fetch Data vs. Update State in React with UseEffect канала vlogize