103 lines
3.0 KiB
Markdown
103 lines
3.0 KiB
Markdown
# qk-factory-pattern: Use Query Key Factories for Complex Applications
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## Priority: CRITICAL
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## Explanation
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For applications with many queries, centralize query key definitions in factory functions. This ensures consistency, enables autocomplete, prevents typos, and makes refactoring safer. Query key factories are the recommended pattern for production applications.
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## Bad Example
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```tsx
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// Scattered, inconsistent key definitions across files
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// file: components/TodoList.tsx
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const { data } = useQuery({
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queryKey: ['todos', 'list'],
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queryFn: fetchTodos,
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})
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// file: components/TodoDetail.tsx
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const { data } = useQuery({
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queryKey: ['todo', id], // Inconsistent: 'todo' vs 'todos'
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queryFn: () => fetchTodo(id),
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})
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// file: components/TodoComments.tsx
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const { data } = useQuery({
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queryKey: ['todoComments', todoId], // Different naming convention
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queryFn: () => fetchComments(todoId),
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})
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// Invalidation is error-prone
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queryClient.invalidateQueries({ queryKey: ['todos'] }) // Misses 'todo' and 'todoComments'
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```
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## Good Example
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```tsx
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// file: lib/query-keys.ts
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export const todoKeys = {
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all: ['todos'] as const,
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lists: () => [...todoKeys.all, 'list'] as const,
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list: (filters: TodoFilters) => [...todoKeys.lists(), filters] as const,
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details: () => [...todoKeys.all, 'detail'] as const,
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detail: (id: number) => [...todoKeys.details(), id] as const,
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comments: (id: number) => [...todoKeys.detail(id), 'comments'] as const,
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}
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export const userKeys = {
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all: ['users'] as const,
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detail: (id: string) => [...userKeys.all, id] as const,
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posts: (id: string) => [...userKeys.detail(id), 'posts'] as const,
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}
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// file: components/TodoList.tsx
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import { todoKeys } from '@/lib/query-keys'
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const { data } = useQuery({
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queryKey: todoKeys.list({ status: 'active' }),
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queryFn: () => fetchTodos({ status: 'active' }),
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})
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// file: components/TodoDetail.tsx
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const { data } = useQuery({
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queryKey: todoKeys.detail(id),
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queryFn: () => fetchTodo(id),
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})
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// Invalidation is type-safe and predictable
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queryClient.invalidateQueries({ queryKey: todoKeys.all }) // Invalidates everything
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queryClient.invalidateQueries({ queryKey: todoKeys.detail(5) }) // Specific todo + comments
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```
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## Query Options Factory Pattern
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```tsx
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// Even better: combine with queryOptions for full type safety
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import { queryOptions } from '@tanstack/react-query'
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export const todoQueries = {
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all: () => queryOptions({
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queryKey: todoKeys.all,
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queryFn: fetchAllTodos,
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}),
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detail: (id: number) => queryOptions({
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queryKey: todoKeys.detail(id),
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queryFn: () => fetchTodo(id),
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staleTime: 5 * 60 * 1000,
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}),
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}
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// Usage
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const { data } = useQuery(todoQueries.detail(5))
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await queryClient.prefetchQuery(todoQueries.detail(5))
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```
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## Context
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- Essential for applications with 10+ different query types
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- Enables IDE autocomplete and typo prevention
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- Makes invalidation patterns discoverable
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- Pairs well with `queryOptions` for full type inference
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- Consider the `@lukemorales/query-key-factory` package for standardized implementation
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