React Query - Overview
Tags: beginners, webdev, javascript, react
Published: 2022-12-07 12:58:27

##Introduction to React Query

React Query is a library for fetching and caching data in React applications. It provides a declarative API for fetching, storing, and retrieving data. React Query is designed to be used with React Hooks.

##Why use React Query?

There are several reasons why you might want to use React Query in your application. First, it can help make your application more responsive by caching data and automatically refetching it when necessary. Second, React Query can improve the performance of your application by batching requests and avoiding unnecessary network traffic. Finally, React Query makes it easier to handle errors by providing a builtin error handling mechanism.

##Setting up React Query

There are two things you need to do to set up React Query in your application: choose a data fetching strategy and configure a caching policy.
The first step is to choose a data fetching strategy. React Query provides two options: useDataProvider and useQueryFetcher. If you're using a thirdparty data provider (like Apollo or Relay), you should use the useDataProvider hook. If you're fetching data directly from an API, you should use the useQueryFetcher hook.
The second step is to configure a caching policy. React Query provides a number of options for how long data should be cached and what should happen when the cache expires. You can read more about these options in the React Query documentation.

##Pagination and error handling

React Query makes it easy to implement pagination in your application. To do so, you simply need to pass a pageSize prop to the useQuery hook. When pagination is enabled, React Query will automatically fetch more data as the user scrolls down the page.
If an error occurs while fetching data, React Query will automatically retry the request using a exponential backoff strategy. If you want to customize this behavior, you can pass a custom errorHandler prop to the useQuery hook.
## When to use React Query?
React Query is well suited for applications that make frequent, realtime data requests (such as chat applications or stock tickers). It's also helpful for applications that have complex caching requirements (such as content management systems). Finally, React Query can be used in any situation where performance is critical and network latency needs to be minimized.

## Setting up React Query
 
1. Make sure to set up React Query in your application before making any requests. You can do this by creating a new instance of the ReactQuery class and passing in some options.
2. When fetching data, be sure to use the query method. This will automatically cache the data and update the UI as needed.
3. If you need to update a piece of data, use the setQueryData method. This will automatically update the cache and the UI.
4. You can use the refetch method to manually refresh data from the server. This is useful if you know that the data has changed on the server and you want to fetch the latest version.
5. Finally, if you need to clear all data from React Query's cache, you can use the reset method. This is useful if you want to start fresh with a new set of data.

##Fetching data with React Query

React Query is a great tool for fetching data in React apps. By following these tips, you can avoid common pitfalls and make the most out of React Query.

##Updating data with React Query

With that said, there are a few ways to update data with React Query. The most common way is to use the setQueryData method. This method will take the data that you want to update and replace the existing data in the query with it. This is the most straightforward way to update data, but it does have a few drawbacks. First, it can be slow if you are updating a lot of data. Second, it can cause problems if you are using pagination, because it will reset the pagination state. Finally, it can be confusing for other developers if they are not aware of the setQueryData method.
Another way to update data is to use the refetch method. This method will fetch the new data from the server and then replace the existing data in the query with it. This is a more efficient way to update data, because it doesn't require downloading the entire dataset again. However, it can be slower than setQueryData if you are only updating a small amount of data.
Finally, you can also use a combination of setQueryData and refetch to update data. This approach is best if you want to update a small amount of data quickly, but you also want to keep the pagination state intact.
So, which approach should you use when updating data with React Query? It depends on your specific needs. If you only need to update a small amount of data, then setQueryData or refetch may be sufficient. However, if you need to update a large amount of data or you need to keep pagination state intact, then using a combination of setQueryData and refetch may be your best option.

##Managing your global state with React Query

When you're using React Query, one of the most important things to keep in mind is to use a unique query key for each piece of data that you're fetching. This is important for two reasons. First, it will help ensure that your queries don't conflict with each other. Secondly, it will allow React Query to properly refetch your data if it changes. If you don't have a unique query key, React Query won't be able to tell that your data has changed and it won't refetch it.
Another important tip is to take advantage of React Query's refetching capabilities. By default, React Query will automatically refetch your data if it changes. However, there are times when you may want to manually trigger a refetch. For example, if you're fetching data from an API and you know that the API has been updated, you can trigger a manual refetch so that your application always has the most uptodate data.
Finally, use the error handling capabilities of React Query to gracefully handle any errors that occur. If an error does occur, React Query will automatically retry the query up to three times before giving up. If you need more control over how errors are handled, you can use the onError callback to customize the behavior. By following these tips, you can ensure that your application always has the most uptodate data and that any errors are handled gracefully.

If you're looking to add React Query to your application, here are 5 tips to keep in mind:

1. Make sure you're using the latest version of React Query – version 21 was recently released and includes some great new features.

2. When configuring React Query, be sure to set the "suspense" option to true – this will ensure that your application can take advantage of all the async data fetching goodness that React Query has to offer.

3. If you're fetching data from an API, be sure to use a "deduping" strategy – otherwise you may end up making unnecessary network requests.

4. Keep an eye on the React Query documentation – they're constantly adding new features and improvements, so it's worth checking in on occasionally.

5. Have fun! React Query is a great tool that can make working with async data in React much easier – so go out there and build something awesome!

Star our [Github repo](https://bit.ly/3QFgAUf) and join the discussion in our [Discord channel](https://bit.ly/3HQtlYo).
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