# [[2023-11-21]] - Redux prefetch blog article
See [[2023-11-21 - Redux prefetch blog prompt]]
Here is a draft blog post about prefetching data on hover using RTK Query:
# Prefetching Data on Hover with RTK Query
RTK Query is a powerful tool for managing server state in Redux applications. It lets you define your API endpoints as simple objects inside the Redux store instead of making raw API calls in components.
For example, here is how we might define a categories API endpoint:
```js
// apiSlice.js
import { createApi } from '@reduxjs/toolkit/query';
export const categoryApi = createApi({
reducerPath: 'categoryApi',
baseQuery: fetchBaseQuery({
baseUrl: 'https://example.com/api/',
}),
endpoints: builder => ({
getCategory: builder.query({
query: url => `category/${url}`
}),
})
})
// Provide auto-generated React hooks for each endpoint
export const {
useGetCategoryQuery,
usePrefetch
} = categoryApi;
```
By defining endpoints like `getCategories`, RTK Query generates React hooks like `useGetCategoryQuery` that components can use to fetch data. It handles all the underlying logic for caching, request deduplication, polling, and more. Multiple components can share the same cached data using these auto-generated hooks.
## Prefetching with the usePrefetch Hook
One useful feature of RTK Query is the ability to prefetch data before a component needs it. This avoids delays when a user navigates to a new screen. RTK Query offers a `usePrefetch` hook that returns a function triggering the actual request, which leads to a cache update.
For an ecommerce site, prefetching category data on hover is useful to accelerate product browsing. When the user hovers over a category, we can fetch that category's products in the background.
Here is how we might prefetch a category and its products:
```jsx
const prefetchCategory = usePrefetch('getCategory');
const prefetchProducts = usePrefetch('getProducts');
return (
<Link
to={`/categories/${category.id}`}
onMouseEnter={() => {
prefetchCategory(category.id);
prefetchProducts({ categoryId: category.id });
}}>
{category.name}
</Link>
);
```
Now when hovering over a category, the category details and products are fetched in anticipation of navigation. This powers a smooth browsing experience.
The same approach could be used for individual products, search suggestions, and any other data that can be preemptively cached. RTK Query handles all the underlying data subscriptions, caching, and request deduplication automatically.