fix: support infinite cache time when hydrating

Author: boschni

src/hydration/hydration.ts

@@ -22,14 +22,22 @@ export interface DehydrateConfig {
   shouldDehydrate?: ShouldDehydrateFunction
 }
 
+function serializePositiveNumber(value: number): number {
+  return value === Infinity ? -1 : value
+}
+
+function deserializePositiveNumber(value: number): number {
+  return value === -1 ? Infinity : value
+}
+
 // Most config is not dehydrated but instead meant to configure again when
 // consuming the de/rehydrated data, typically with useQuery on the client.
 // Sometimes it might make sense to prefetch data on the server and include
 // in the html-payload, but not consume it on the initial render.
 function dehydrateQuery(query: Query): DehydratedQuery {
   return {
     config: {
-      cacheTime: query.cacheTime,
+      cacheTime: serializePositiveNumber(query.cacheTime),
     },
     data: query.state.data,
     queryKey: query.queryKey,
@@ -80,7 +88,9 @@ export function hydrate(cache: QueryCache, dehydratedState: unknown): void {
         queryKey: dehydratedQuery.queryKey,
         queryHash: dehydratedQuery.queryHash,
         options: {
-          cacheTime: dehydratedQuery.config.cacheTime,
+          cacheTime: deserializePositiveNumber(
+            dehydratedQuery.config.cacheTime
+          ),
         },
       })
       cache.add(query)

src/hydration/tests/hydration.test.tsx

@@ -88,6 +88,22 @@ describe('dehydration and rehydration', () => {
     hydrationCache.clear()
   })
 
+  test('should serialize the cacheTime correctly', async () => {
+    const cache = new QueryCache()
+    const client = new QueryClient({ cache })
+    await client.prefetchQuery('string', () => fetchData('string'), {
+      cacheTime: Infinity,
+    })
+    const dehydrated = dehydrate(cache)
+    const stringified = JSON.stringify(dehydrated)
+    const parsed = JSON.parse(stringified)
+    const hydrationCache = new QueryCache()
+    hydrate(hydrationCache, parsed)
+    expect(hydrationCache.find('string')?.cacheTime).toBe(Infinity)
+    cache.clear()
+    hydrationCache.clear()
+  })
+
   test('should work with complex keys', async () => {
     const cache = new QueryCache()
     const client = new QueryClient({ cache })