Fix/cache before set (#750)

.changeset/witty-swans-tap.md

@@ -0,0 +1,6 @@
+---
+"@headstartwp/core": patch
+"@headstartwp/next": patch
+---
+
+Fix cache.beforeSet

packages/next/src/data/server/__tests__/fetchHookDataa-cache.ts

@@ -2,6 +2,7 @@ import { enableFetchMocks } from 'jest-fetch-mock';
 import { HeadlessConfig, setHeadstartWPConfig } from '@headstartwp/core';
 
 import { usePosts } from '../../hooks/usePosts';
+import { usePost } from '../../hooks/usePost';
 
 import { fetchHookData } from '../fetchHookData';
 import cache from '../cache';
@@ -125,4 +126,45 @@ describe('fetchHookData caching', () => {
 		expect(config.cache.beforeSet).toHaveBeenCalledTimes(1);
 		expect(result.data.isCached).toBe(true);
 	});
+
+	it('caches with beforeSet without mutating the fetched data', async () => {
+		const config = {
+			useWordPressPlugin: true,
+			cache: {
+				enabled: true,
+
+				afterGet: async (options, data) => {
+					return data;
+				},
+
+				beforeSet: async (options, data) => {
+					return {
+						...data,
+						result: {
+							...data.result,
+							beforeSetField: true,
+						},
+					};
+				},
+
+				cacheHandler: {
+					set: async (key, data, ttl) => {
+						cache.set(key, data, ttl);
+					},
+					get: async (key) => {
+						return cache.get(key);
+					},
+				},
+			},
+		} satisfies HeadlessConfig;
+
+		setHeadstartWPConfig(config);
+
+		fetchMock.mockResponseOnce(JSON.stringify([{ id: 10 }]));
+
+		const result = await fetchHookData(usePost.fetcher(), {}, { params: { slug: 'test3' } });
+
+		expect(result.data.result.id).toBe(10);
+		expect(result.data.result.beforeSetField).toBeUndefined();
+	});
 });

packages/next/src/data/server/fetchHookData.ts

@@ -265,7 +265,7 @@ export async function fetchHookData<T = unknown, P extends EndpointParams = Endp
 			}
 
 			if (typeof cache.beforeSet === 'function') {
-				data = await cache.beforeSet(
+				const beforeSetData = await cache.beforeSet(
 					{
 						fetchStrategy,
 						params,
@@ -275,9 +275,11 @@ export async function fetchHookData<T = unknown, P extends EndpointParams = Endp
 					},
 					data,
 				);
-			}
 
-			await cache.cacheHandler.set(cacheKey, data, cache.ttl);
+				await cache.cacheHandler.set(cacheKey, beforeSetData, cache.ttl);
+			} else {
+				await cache.cacheHandler.set(cacheKey, data, cache.ttl);
+			}
 		}
 	} else {
 		data.isCached = true;