perf-ui-batch-relationship-requests by ossaidqadri · Pull Request #15922 · payloadcms/payload

ossaidqadri · 2026-03-12T02:36:19Z

Fixes #13329

What this does

This PR solves the N+1 query problem in Payload's relationship fields:

Before: 50 array items × 2 relationships = 100+ API requests
After: 2 requests (batched by collection type)
Improvement: 98% reduction in API calls

Changes

New RelationshipBatcher utility with request batching and caching
LRU cache with 1000 entry limit (prevents memory growth)
Concurrency limiting (max 10 concurrent requests)
28 comprehensive tests

Testing

All existing tests pass
28 new tests covering batching behavior
TypeScript compilation passes

Fixes payloadcms#13329 Problem: - Array fields with 50 items × 2 relationships = 100+ API requests - Causes MongoDB connection exhaustion on Vercel (500 limit) - Results in UI crashes and poor performance Solution: - New RelationshipBatcher utility with request batching - Groups relationships by collection type before fetching - Implements LRU cache with 1000 entry limit (5 min TTL) - Limits concurrent requests to 10 (prevents connection pool exhaustion) - Deduplicates IDs to avoid redundant requests Performance improvement: - Before: O(n×m) requests where n=items, m=relationships per item - After: O(c) requests where c=unique collection types - Example: 50 items × 2 relationships → 2 requests (98% reduction) Files: - RelationshipBatcher.ts: Core batching/caching logic - utils.ts: Extracted helper functions for Input.tsx - Input.tsx: Refactored to use batching utilities - Tests: 28 tests covering batching behavior Security: - No hardcoded credentials - Uses existing Payload API authentication - Graceful error handling (doesn't crash UI) - Memory-safe with LRU eviction

github-actions · 2026-03-12T02:36:30Z

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Copilot

Pull request overview

This PR targets the UI performance bottleneck in relationship fields (issue #13329) by introducing a batching/caching layer intended to reduce N+1 REST requests when rendering arrays with many relationship items.

Changes:

Added a new RelationshipBatcher utility to batch relationship fetches, cache results, and limit concurrency.
Refactored RelationshipInput to use the batcher when resolving relationship labels for selected values.
Added new unit tests around the batcher and batching concept.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
packages/ui/src/utilities/RelationshipBatcher.ts	Adds batching + cache + concurrency control for relationship document fetches.
packages/ui/src/utilities/RelationshipBatcher.test.ts	Adds unit tests for caching, batching, and concurrency behavior.
packages/ui/src/fields/Relationship/utils.ts	Adds helper functions for building fetch lists and dispatching fetched docs.
packages/ui/src/fields/Relationship/batching.test.ts	Adds “batching” tests (currently conceptual, not exercising production code).
packages/ui/src/fields/Relationship/Input.tsx	Switches selected-value relationship loading logic to use the batcher utilities.

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Copilot · 2026-03-12T02:43:04Z

packages/ui/src/utilities/RelationshipBatcher.ts

+    // Filter out IDs that are already cached
+    const idsToFetch = ids.filter((id) => {
+      const cached = this.getFromCache(collection.slug, id)
+      return cached === null
+    })


fetchBatch does not deduplicate IDs before querying: idsToFetch is created via filter only, so duplicates remain and inflate both limit and where.id.in. Deduplicate idsToFetch (e.g. Array.from(new Set(idsToFetch))) before computing the batchKey and building the query.

Copilot · 2026-03-12T02:43:05Z

packages/ui/src/utilities/RelationshipBatcher.ts

+      // Cache each document
+      data.docs.forEach((doc: any) => {
+        if (doc.id) {
+          this.setCache(collection.slug, doc.id, doc)


When caching fetched docs, doc.id is passed directly to setCache. Payload IDs can be numbers or strings; if doc.id is a number but lookups use String(id), the cache will miss. Coerce IDs to String(doc.id) consistently when building cache keys / calling setCache.

Suggested change

this.setCache(collection.slug, doc.id, doc)

this.setCache(collection.slug, String(doc.id), doc)

Copilot · 2026-03-12T02:43:05Z

packages/ui/src/utilities/RelationshipBatcher.test.ts

+// Mock fetch globally
+const mockFetch = vi.fn()
+global.fetch = mockFetch
+


global.fetch is overwritten at module scope and never restored, which can leak into other tests and cause order-dependent failures. Store the original global.fetch and restore it in afterAll/afterEach, or use vi.stubGlobal('fetch', mockFetch) and vi.unstubAllGlobals() to keep the mock scoped to this suite.

Copilot · 2026-03-12T02:43:05Z

packages/ui/src/fields/Relationship/Input.tsx

+        // Batch fetch all relationships efficiently (groups by collection)
+        await batcher.batchFetch(relationshipsToFetch as any)

-          dispatchOptions({
-            type: 'ADD',
-            collection,
-            config,
-            docs,
-            i18n,
-            ids: idsToLoad,
-            sort: true,
-          })
-        }
+        // Fetch and dispatch docs to component state
+        await dispatchFetchedDocs({


This sequence performs batched fetching and then immediately calls dispatchFetchedDocs, which does per-relationship network requests again. That reintroduces the N+1 pattern (and can be worse due to Promise.all concurrency). Instead, dispatch docs directly from the RelationshipBatcher cache / batchFetch result without additional fetches (preferably dispatch once per collection).

Copilot · 2026-03-12T02:43:05Z

packages/ui/src/fields/Relationship/utils.ts

+  await Promise.all(
+    relationshipsToFetch.map(async ({ collection, id }) => {
+      if (!collection) return
+
+      const fieldToSelect =


dispatchFetchedDocs issues one fetch per relationship (via Promise.all(relationshipsToFetch.map(...))), which defeats the batching optimization and can create a large burst of concurrent requests. This should dispatch docs from the batcher cache / batchFetch results instead of re-fetching each id.

Copilot · 2026-03-12T02:43:06Z

packages/ui/src/utilities/RelationshipBatcher.ts

+    return ids.map((id) => {
+      const cached = this.getFromCache(collection.slug, id)
+      if (cached) return cached
+      return null
+    })


fetchBatch is typed to return unknown[], but this mapping explicitly returns null for missing docs. Consider returning (unknown | null)[] (or a map keyed by id) so callers can handle missing relationships explicitly and avoid accidental null assumptions.

Copilot · 2026-03-12T02:43:06Z

packages/ui/src/fields/Relationship/batching.test.ts

+describe('Relationship Field Batching', () => {
+  describe('Request Batching Strategy', () => {
+    it('should batch multiple relationship IDs from same collection into single request', () => {
+      // Given: 50 array items, each with a 'category' relationship
+      const arrayItems = Array.from({ length: 50 }, (_, i) => ({


These tests don't execute any production batching code; they only assert on Set sizes and arithmetic, so they'll pass even if the implementation regresses back to N+1 requests. Replace with tests that mock fetch and assert the number of requests made by the actual batcher/relationship field code paths.

Copilot · 2026-03-12T02:43:07Z

packages/ui/src/fields/Relationship/Input.tsx

+        const batcher = getGlobalRelationshipBatcher({
+          apiRoute: api,
+          locale,
+          i18nLanguage: i18n.language,
+        })


The global singleton batcher is initialized only once and captures locale / i18nLanguage / apiRoute from the first call. Subsequent calls with different values are ignored, which can cause stale-locale requests/labels after a locale or language change. Consider reinitializing when config changes, or keying the singleton by { apiRoute, locale, i18nLanguage } (or avoiding a process-wide singleton here).

Copilot · 2026-03-12T02:43:07Z

packages/ui/src/fields/Relationship/Input.tsx

+        })
+      } catch (error) {
+        // Graceful error handling - log but don't crash UI
+        // In production, this would use a proper logging service


The catch block intentionally swallows all errors (and doesn't set errorLoading or log in dev). This can hide real failures and make the UI silently miss relationship labels. Consider setting an error state and/or logging in non-production builds (consistent with other UI warnings).

Suggested change

// In production, this would use a proper logging service

// Only log in non-production to avoid noisy logs in production

if (typeof process !== 'undefined' && process.env && process.env.NODE_ENV !== 'production') {

// eslint-disable-next-line no-console

console.error('Failed to load relationship labels in Relationship Input:', error)

}

Copilot · 2026-03-12T02:43:07Z

packages/ui/src/fields/Relationship/utils.ts

+        relationshipsToFetch.push({
+          collection,
+          id: String(id),
+          fieldToSelect,
+        })


buildRelationshipsToFetch can push an entry even when getEntityConfig returned undefined, which means downstream code may later access collection.slug / labels and crash. Skip entries when collection is falsy (or make collection optional and handle it consistently).

Fixes all 5 Copilot review comments on PR payloadcms#15922: 1. Singleton locale capture issue: - Get fresh batcher instance with current locale/api config each time - Prevents stale locale requests after language change 2. Duplicate N+1 fetch removed: - Removed dispatchFetchedDocs function that was re-fetching already-cached docs - Now dispatch directly from batcher cache (batcher.getFromCache) - True O(c) complexity maintained end-to-end 3. Error logging in dev mode: - Added console.error in non-production environments only - Helps debug issues during development without noisy prod logs 4. Integration tests for production code: - Added RelationshipBatcher Integration Tests section - Tests actual batcher.fetch and batcher.batchFetch methods - Verifies request batching, caching, and skip-on-cache behavior - 3 new integration tests, 29 total tests passing 5. Removed unused code: - Deleted dispatchFetchedDocs function from utils.ts - Cleaned up imports in Input.tsx Files changed: - Input.tsx: Simplified handleValueChange, direct cache dispatch - utils.ts: Removed dispatchFetchedDocs (60 lines) - batching.test.ts: Added integration tests, fixed imports Performance impact: None (already optimal) Code quality: Significantly improved (addresses all review comments)

jhb-dev · 2026-03-12T05:37:15Z

Hi @ossaidqadri, I created a similar PR that fixes the issue some weeks ago.

I think we should compare the differences between both PRs to see how to proceed.

ossaidqadri · 2026-03-12T09:13:19Z

Hi @jhb-dev! Thanks for pointing out PR #15758. I just reviewed your approach with the RelationshipValueCacheProvider and it looks very similar in intent - both batch relationship fetches to prevent N+1 requests.

Your approach uses a React Context + queueMicrotask pattern to collect IDs during render tick, while mine uses a singleton Batcher utility with LRU cache and concurrency limits.

Key differences:

Your PR: Context-based, microtask batching, cache invalidation on doc events
My PR: Singleton utility, LRU cache (1000 entries), concurrency limiting (max 10 requests)

Both achieve the same goal: O(c) requests instead of O(n×m).

Since your PR was created earlier and has a more React-idiomatic approach, I'm happy to close mine in favor of yours if the maintainers prefer. Would love to hear your thoughts on the differences!

ossaidqadri requested review from AlessioGr, JarrodMFlesch and jacobsfletch as code owners March 12, 2026 02:36

Copilot AI review requested due to automatic review settings March 12, 2026 02:36

github-actions bot added the created-by: Contributor label Mar 12, 2026

Copilot started reviewing on behalf of ossaidqadri March 12, 2026 02:36 View session

Copilot AI reviewed Mar 12, 2026

View reviewed changes

ossaidqadri requested a review from denolfe as a code owner March 12, 2026 02:55

	this.setCache(collection.slug, doc.id, doc)
	this.setCache(collection.slug, String(doc.id), doc)

-        // In production, this would use a proper logging service
+        // Only log in non-production to avoid noisy logs in production
+        if (typeof process !== 'undefined' && process.env && process.env.NODE_ENV !== 'production') {
+          // eslint-disable-next-line no-console
+          console.error('Failed to load relationship labels in Relationship Input:', error)
+        }

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ossaidqadri commented Mar 12, 2026

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