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Advanced React Query Patterns for Modern Applications

Disclaimer: This is a personal summary and interpretation based on a YouTube video. It is not official material and not endorsed by the original creator. All rights remain with the respective creators.

This document summarizes the key takeaways from the video. I highly recommend watching the full video for visual context and coding demonstrations.

Before You Get Started

  • I summarize key points to help you learn and review quickly.
  • Simply click on Ask AI links to dive into any topic you want.

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Learn Differently: Analogy | Storytelling | Cheatsheet | Mindmap | Flashcards | Practical Projects | Code Examples | Common Mistakes

Check Understanding: Generate Quiz | Interview Me | Refactor Challenge | Assessment Rubric | Next Steps

Basic Query Setup

React Query simplifies fetching data with its useQuery hook, which handles loading, errors, and caching automatically. Start by importing useQuery, providing a query function (like an async API call), and a unique query key for caching. It returns useful states like data, isPending, isError, and a refetch function to retry on failures.

  • Key Takeaway/Example: Use the returned states to render loading indicators, error alerts with retry buttons, or the actual data table.
  • Link for More Details: Ask AI: Basic Query Setup

Custom Query Hooks

Extract queries into reusable custom hooks to keep components clean and readable. Create a function like useContacts that wraps useQuery with your query function and key, then call it in components to handle states and UI rendering.

  • Key Takeaway/Example: This separation makes code more maintainable, especially when reusing the same query across multiple parts of the app.
  • Link for More Details: Ask AI: Custom Query Hooks

Data Transformation with Selectors

Use the 'select' option in useQuery to transform backend data before it reaches your component, like calculating a count from a list. This prevents unnecessary re-renders in large apps since React Query memoizes the selected value.

  • Key Takeaway/Example: For a contacts list, select the length to display a count without re-rendering the whole component if only unrelated data changes.
select: (data) => data.contacts.length

Using Query Options for Flexibility

Instead of a direct hook, export query configurations as objects using queryOptions. This allows components to spread and customize options like selectors when calling useQuery.

Parameterized Queries

For queries needing inputs like IDs, turn the query function into one that accepts parameters, including them in the query key to ensure proper caching and avoid fetching wrong data.

  • Key Takeaway/Example: For fetching a single contact, pass the ID to both the query function and key to cache per ID.
queryKey: ['contact', contactId]

Pagination Implementation

Handle pagination by parameterizing queries with page number and item count, updating state on user interactions like 'next page' clicks, which triggers React Query to refetch automatically.

  • Key Takeaway/Example: Use React state for the current page, and pass it to the parameterized query for seamless data updates.
  • Link for More Details: Ask AI: Pagination Implementation

Prefetching Data

Prefetch upcoming data in the background using queryClient.prefetchQuery in a useEffect, based on current state like page number, to eliminate loading states for users.

  • Key Takeaway/Example: On page change, prefetch the next page or even multiple pages ahead for instant navigation.
  • Link for More Details: Ask AI: Prefetching Data

Infinite Queries for Scrolling

Use useInfiniteQuery for infinite scrolling or 'load more' features. Define a query function that uses a cursor for pagination, and specify how to get the next page param from results.

  • Key Takeaway/Example: React Query manages cursor states internally; use isFetchingNextPage and fetchNextPage for UI controls like buttons.
  • Link for More Details: Ask AI: Infinite Queries for Scrolling

Query Key Factories

Centralize query keys in a factory object with methods for base and specific keys, reducing errors when accessing or invalidating them across the app.

  • Key Takeaway/Example: Define an object with all() for base and list(params) for specifics, then use these in queries and mutations.
  • Link for More Details: Ask AI: Query Key Factories

Mutations for Data Changes

Use useMutation for updates like deletions, providing a mutate function, pending state, and callbacks for success/error to show notifications.

Automatic Query Invalidation

Simplify invalidation by adding a meta object to mutations with invalidatesQuery keys, then handle it globally in the queryClient's mutation defaults.

  • Key Takeaway/Example: This reduces repetition and cleans up mutation code, automatically refreshing queries on settlement.
  • Link for More Details: Ask AI: Automatic Query Invalidation

Global Error Handling

Set up global error callbacks in queryClient to handle common cases like 401 unauthorized errors, logging out users across all mutations.

  • Key Takeaway/Example: Centralize logic to avoid per-mutation error checks, improving scalability.
  • Link for More Details: Ask AI: Global Error Handling

Optimistic Updates

Show immediate UI changes before backend confirmation. Implement at UI level by filtering pending mutations or at cache level by updating query data directly.

  • Key Takeaway/Example: For deletions, cancel queries, filter cache data, and rollback on error for app-wide consistency.
  • Link for More Details: Ask AI: Optimistic Updates

Suspense Queries for Loading

Replace per-component loaders with useSuspenseQuery and React's Suspense for a global skeleton, reducing flickering in query-heavy apps.

About the summarizer

I'm Ali Sol, a Backend Developer. Learn more: