Experiment with React-Query

eslint.config.mjs

@@ -1,6 +1,7 @@
 import { dirname } from "path";
 import { fileURLToPath } from "url";
 import { FlatCompat } from "@eslint/eslintrc";
+import pluginQuery from '@tanstack/eslint-plugin-query';
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = dirname(__filename);
@@ -11,6 +12,7 @@ const compat = new FlatCompat({
 
 const eslintConfig = [
   ...compat.extends("next/core-web-vitals", "next/typescript"),
+  ...pluginQuery.configs['flat/recommended'],
 ];
 
 export default eslintConfig;

package.json

@@ -9,6 +9,7 @@
     "lint": "next lint"
   },
   "dependencies": {
+    "@tanstack/react-query": "^5.71.3",
     "lowdb": "^7.0.1",
     "match-sorter": "^8.0.0",
     "next": "15.2.4",
@@ -21,6 +22,7 @@
   "devDependencies": {
     "@eslint/eslintrc": "^3",
     "@next/eslint-plugin-next": "^15.2.4",
+    "@tanstack/eslint-plugin-query": "^5.68.0",
     "@types/node": "^20",
     "@types/react": "^19",
     "@types/react-dom": "^19",

pnpm-lock.yaml

@@ -8,6 +8,9 @@ importers:
 
   .:
     dependencies:
+      '@tanstack/react-query':
+        specifier: ^5.71.3
+        version: 5.71.3(react@19.1.0)
       lowdb:
         specifier: ^7.0.1
         version: 7.0.1
@@ -39,6 +42,9 @@ importers:
       '@next/eslint-plugin-next':
         specifier: ^15.2.4
         version: 15.2.4
+      '@tanstack/eslint-plugin-query':
+        specifier: ^5.68.0
+        version: 5.68.0(eslint@9.23.0)(typescript@5.8.2)
       '@types/node':
         specifier: ^20
         version: 20.17.29
@@ -324,6 +330,19 @@ packages:
   '@swc/helpers@0.5.15':
     resolution: {integrity: sha512-JQ5TuMi45Owi4/BIMAJBoSQoOJu12oOk/gADqlcUL9JEdHB8vyjUSsxqeNXnmXHjYKMi2WcYtezGEEhqUI/E2g==}
 
+  '@tanstack/eslint-plugin-query@5.68.0':
+    resolution: {integrity: sha512-w/+y5LILV1GTWBB2R/lKfUzgocKXU1B7O6jipLUJhmxCKPmJFy5zpfR1Vx7c6yCEsQoKcTbhuR/tIy+1sIGaiA==}
+    peerDependencies:
+      eslint: ^8.57.0 || ^9.0.0
+
+  '@tanstack/query-core@5.71.3':
+    resolution: {integrity: sha512-SW7PXYpKiQCZU5pPOXG2UiHX1oSAxLyxoJiYbQ3aLYiABJW0UnfBZ9PVnO/x4ZCIVK30wfDn0h6Mrsr10q922Q==}
+
+  '@tanstack/react-query@5.71.3':
+    resolution: {integrity: sha512-4GZxKqiMX+CH4CxXiUBNipbqzk2V5jUU8Z4d6J+lSDu8OejcLtjx1hEDJzabFZHwd+ZHCsYLAJmM54kCS1/ekA==}
+    peerDependencies:
+      react: ^18 || ^19
+
   '@tybys/wasm-util@0.9.0':
     resolution: {integrity: sha512-6+7nlbMVX/PVDCwaIQ8nTOPveOcFLSt8GcXdx8hD0bt39uWxYT88uXzqTd4fTvqta7oeUJqudepapKNt2DYJFw==}
 
@@ -1779,6 +1798,21 @@ snapshots:
     dependencies:
       tslib: 2.8.1
 
+  '@tanstack/eslint-plugin-query@5.68.0(eslint@9.23.0)(typescript@5.8.2)':
+    dependencies:
+      '@typescript-eslint/utils': 8.29.0(eslint@9.23.0)(typescript@5.8.2)
+      eslint: 9.23.0
+    transitivePeerDependencies:
+      - supports-color
+      - typescript
+
+  '@tanstack/query-core@5.71.3': {}
+
+  '@tanstack/react-query@5.71.3(react@19.1.0)':
+    dependencies:
+      '@tanstack/query-core': 5.71.3
+      react: 19.1.0
+
   '@tybys/wasm-util@0.9.0':
     dependencies:
       tslib: 2.8.1
@@ -2264,8 +2298,8 @@ snapshots:
       '@typescript-eslint/parser': 8.29.0(eslint@9.23.0)(typescript@5.8.2)
       eslint: 9.23.0
       eslint-import-resolver-node: 0.3.9
-      eslint-import-resolver-typescript: 3.10.0(eslint-plugin-import@2.31.0)(eslint@9.23.0)
-      eslint-plugin-import: 2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint-import-resolver-typescript@3.10.0)(eslint@9.23.0)
+      eslint-import-resolver-typescript: 3.10.0(eslint-plugin-import@2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint@9.23.0))(eslint@9.23.0)
+      eslint-plugin-import: 2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint-import-resolver-typescript@3.10.0(eslint-plugin-import@2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint@9.23.0))(eslint@9.23.0))(eslint@9.23.0)
       eslint-plugin-jsx-a11y: 6.10.2(eslint@9.23.0)
       eslint-plugin-react: 7.37.4(eslint@9.23.0)
       eslint-plugin-react-hooks: 5.2.0(eslint@9.23.0)
@@ -2284,7 +2318,7 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
-  eslint-import-resolver-typescript@3.10.0(eslint-plugin-import@2.31.0)(eslint@9.23.0):
+  eslint-import-resolver-typescript@3.10.0(eslint-plugin-import@2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint@9.23.0))(eslint@9.23.0):
     dependencies:
       '@nolyfill/is-core-module': 1.0.39
       debug: 4.4.0
@@ -2295,22 +2329,22 @@ snapshots:
       tinyglobby: 0.2.12
       unrs-resolver: 1.3.3
     optionalDependencies:
-      eslint-plugin-import: 2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint-import-resolver-typescript@3.10.0)(eslint@9.23.0)
+      eslint-plugin-import: 2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint-import-resolver-typescript@3.10.0(eslint-plugin-import@2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint@9.23.0))(eslint@9.23.0))(eslint@9.23.0)
     transitivePeerDependencies:
       - supports-color
 
-  eslint-module-utils@2.12.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.10.0)(eslint@9.23.0):
+  eslint-module-utils@2.12.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.10.0(eslint-plugin-import@2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint@9.23.0))(eslint@9.23.0))(eslint@9.23.0):
     dependencies:
       debug: 3.2.7
     optionalDependencies:
       '@typescript-eslint/parser': 8.29.0(eslint@9.23.0)(typescript@5.8.2)
       eslint: 9.23.0
       eslint-import-resolver-node: 0.3.9
-      eslint-import-resolver-typescript: 3.10.0(eslint-plugin-import@2.31.0)(eslint@9.23.0)
+      eslint-import-resolver-typescript: 3.10.0(eslint-plugin-import@2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint@9.23.0))(eslint@9.23.0)
     transitivePeerDependencies:
       - supports-color
 
-  eslint-plugin-import@2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint-import-resolver-typescript@3.10.0)(eslint@9.23.0):
+  eslint-plugin-import@2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint-import-resolver-typescript@3.10.0(eslint-plugin-import@2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint@9.23.0))(eslint@9.23.0))(eslint@9.23.0):
     dependencies:
       '@rtsao/scc': 1.1.0
       array-includes: 3.1.8
@@ -2321,7 +2355,7 @@ snapshots:
       doctrine: 2.1.0
       eslint: 9.23.0
       eslint-import-resolver-node: 0.3.9
-      eslint-module-utils: 2.12.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.10.0)(eslint@9.23.0)
+      eslint-module-utils: 2.12.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.10.0(eslint-plugin-import@2.31.0(@typescript-eslint/parser@8.29.0(eslint@9.23.0)(typescript@5.8.2))(eslint@9.23.0))(eslint@9.23.0))(eslint@9.23.0)
       hasown: 2.0.2
       is-core-module: 2.16.1
       is-glob: 4.0.3

src/app/(sidebar)/layout.tsx

@@ -2,9 +2,14 @@ import React, { Suspense } from "react";
 import Link from "next/link";
 import Form from "next/form";
 import ContactList from "./sidebar-contacts";
-import { createEmptyContact } from "@/app/data";
+import { createEmptyContact, getContacts } from "@/app/data";
 import { revalidatePath } from "next/cache";
 import { fetchContacts } from "@/app/(sidebar)/loaders";
+import {
+  QueryClient,
+  dehydrate,
+  HydrationBoundary,
+} from "@tanstack/react-query";
 
 async function newContact() {
   "use server";
@@ -12,12 +17,22 @@ async function newContact() {
   revalidatePath('/');
 }
 
-export default function SidebarRootLayout({
+export default async function SidebarRootLayout({
   children,
 }: Readonly<{
   children: React.ReactNode;
 }>) {
-  const contacts = fetchContacts();
+  const queryClient = new QueryClient();
+  await queryClient.prefetchQuery({
+    queryKey: ['contacts'],
+    queryFn: () => getContacts(),
+  });
+  /*
+   * The problem here was that the `fetch` that Next uses inside function called server-side is the Node one, where you
+   * cannot use Relative Paths!!!
+   * So the most simple solution was to bypass the fetch and directly call the data function here.
+   * Basically the API is used only for the data refresh.
+   */
 
   return (
     <>
@@ -43,9 +58,9 @@ export default function SidebarRootLayout({
           </Form>
         </div>
         <nav>
-          <Suspense fallback={<div>Loading...</div>}>
-            <ContactList contacts={contacts}/>
-          </Suspense>
+          <HydrationBoundary state={dehydrate(queryClient)}>
+            <ContactList/>
+          </HydrationBoundary>
         </nav>
       </div>
       <div id={'detail'}>

src/app/(sidebar)/loaders.ts

@@ -1,11 +1,21 @@
-import { getContact, getContacts } from "@/app/data";
+import { ContactRecord } from "@/app/data";
 
-export const fetchContacts = async () => {
-  console.log("fetch contacts")
-  return await getContacts();
-};
+export async function fetchContacts() {
+  console.log("fetchContacts()");
+  const response = await fetch('/api/contacts');
+  if (!response.ok) {
+    console.log("ERROR!?");
+    throw new Error(`Network Error ${response.status}: ${response.statusText}`);
+  }
+  const data: { contacts: ContactRecord[] } = await response.json();
+  return data.contacts;
+}
 
-export const fetchContact = async (contactId: string) => {
-  console.log(`fetch contact ${contactId}`)
-  return await getContact(contactId);
-};
+export async function fetchContact(contactId: string) {
+  console.log("fetchContacts()");
+  const response = await fetch(`/api/contacts/${contactId}`);
+  if (!response.ok) {
+    throw new Error(`Network Error ${response.status}: ${response.statusText}`);
+  }
+  return (await response.json())['contact'] as ContactRecord;
+}

src/app/(sidebar)/sidebar-contacts.tsx

@@ -1,12 +1,19 @@
-import { ContactRecord } from "@/app/data";
-import React, { use } from "react";
-import Link from "next/link";
+"use client";
+
+import Link from "next/link";
+import { useQuery } from "@tanstack/react-query";
+import { fetchContacts } from "@/app/(sidebar)/loaders";
+
+export default function ContactList() {
+  const { data } = useQuery({
+    queryKey: ['contacts'],
+    queryFn: () => fetchContacts()
+  });
+  if (data === undefined) return <div>Error during prefetch...</div>;
 
-export default function ContactList({ contacts }: { contacts: Promise<ContactRecord[]> }) {
-  const allContacts = use(contacts);
   return (
     <ul>
-      {allContacts.map((c) => (
+      {data.map((c) => (
         <li key={c.id}>
           <Link href={`/contacts/${c.id}`}>
             {c.first || c.last ? (

src/app/api/contacts/[contactId]/route.ts

@@ -0,0 +1,11 @@
+import { NextResponse } from 'next/server';
+import { getContact } from "@/app/data";
+
+export async function GET(
+  { params }: { params: Promise<{ contactId: string }> }
+) {
+  const { contactId } = await params;
+  console.log(`fetch contact ${contactId}`);
+  const contact = await getContact(contactId);
+  return NextResponse.json({ contact: contact });
+}

src/app/api/contacts/route.ts

@@ -0,0 +1,8 @@
+import { NextResponse } from 'next/server';
+import { getContacts } from "@/app/data";
+
+export async function GET() {
+  console.log("fetch contacts");
+  const contacts = await getContacts();
+  return NextResponse.json({ contacts: contacts });
+}

src/app/layout.tsx

@@ -2,6 +2,7 @@ import React from "react";
 import type { Metadata } from "next";
 
 import "./globals.css";
+import Providers from "@/app/providers";
 
 export const metadata: Metadata = {
   title: "Next.js Address Book",
@@ -16,7 +17,7 @@ export default function RootLayout({
   return (
     <html lang="en">
     <body>
-    {children}
+    <Providers>{children}</Providers>
     </body>
     </html>
   );

src/app/providers.tsx

@@ -0,0 +1,49 @@
+'use client';
+
+// Since QueryClientProvider relies on useContext under the hood, we have to put 'use client' on top
+import {
+  isServer,
+  QueryClient,
+  QueryClientProvider,
+} from '@tanstack/react-query';
+import React from "react";
+
+function makeQueryClient() {
+  return new QueryClient({
+    defaultOptions: {
+      queries: {
+        // With SSR, we usually want to set some default staleTime
+        // above 0 to avoid refetching immediately on the client
+        staleTime: 60 * 1000,
+      },
+    },
+  });
+}
+
+let browserQueryClient: QueryClient | undefined = undefined;
+
+function getQueryClient() {
+  if (isServer) {
+    // Server: always make a new query client
+    return makeQueryClient();
+  } else {
+    // Browser: make a new query client if we don't already have one
+    // This is very important, so we don't re-make a new client if React
+    // suspends during the initial render. This may not be needed if we
+    // have a suspense boundary BELOW the creation of the query client
+    if (!browserQueryClient) browserQueryClient = makeQueryClient();
+    return browserQueryClient;
+  }
+}
+
+export default function Providers({ children }: { children: React.ReactNode }) {
+  // NOTE: Avoid useState when initializing the query client if you don't
+  //       have a suspense boundary between this and the code that may
+  //       suspend because React will throw away the client on the initial
+  //       render if it suspends and there is no boundary
+  const queryClient = getQueryClient();
+
+  return (
+    <QueryClientProvider client={queryClient}>{children}</QueryClientProvider>
+  );
+}