Fix issues with SSR

examples/react/next-server-actions-zod/.gitignore

@@ -0,0 +1,36 @@
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+.yarn/install-state.gz
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# local env files
+.env*.local
+
+# vercel
+.vercel
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts

examples/react/next-server-actions-zod/README.md

@@ -0,0 +1,36 @@
+This is a [Next.js](https://nextjs.org/) project bootstrapped with [`create-next-app`](https://github.com/vercel/next.js/tree/canary/packages/create-next-app).
+
+## Getting Started
+
+First, run the development server:
+
+```bash
+npm run dev
+# or
+yarn dev
+# or
+pnpm dev
+# or
+bun dev
+```
+
+Open [http://localhost:3000](http://localhost:3000) with your browser to see the result.
+
+You can start editing the page by modifying `app/page.tsx`. The page auto-updates as you edit the file.
+
+This project uses [`next/font`](https://nextjs.org/docs/basic-features/font-optimization) to automatically optimize and load Inter, a custom Google Font.
+
+## Learn More
+
+To learn more about Next.js, take a look at the following resources:
+
+- [Next.js Documentation](https://nextjs.org/docs) - learn about Next.js features and API.
+- [Learn Next.js](https://nextjs.org/learn) - an interactive Next.js tutorial.
+
+You can check out [the Next.js GitHub repository](https://github.com/vercel/next.js/) - your feedback and contributions are welcome!
+
+## Deploy on Vercel
+
+The easiest way to deploy your Next.js app is to use the [Vercel Platform](https://vercel.com/new?utm_medium=default-template&filter=next.js&utm_source=create-next-app&utm_campaign=create-next-app-readme) from the creators of Next.js.
+
+Check out our [Next.js deployment documentation](https://nextjs.org/docs/deployment) for more details.

examples/react/next-server-actions-zod/next.config.mjs

@@ -0,0 +1,6 @@
+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  reactStrictMode: true,
+}
+
+export default nextConfig

examples/react/next-server-actions-zod/package.json

@@ -0,0 +1,24 @@
+{
+  "name": "@tanstack/form-example-react-next-server-actions-zod",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "next dev",
+    "build": "next build",
+    "_test:types": "tsc"
+  },
+  "dependencies": {
+    "@tanstack/react-form-nextjs": "^1.28.0",
+    "@tanstack/react-store": "^0.8.0",
+    "next": "16.0.5",
+    "react": "^19.0.0",
+    "react-dom": "^19.0.0",
+    "zod": "^3.25.76"
+  },
+  "devDependencies": {
+    "@types/node": "^24.1.0",
+    "@types/react": "^19.0.7",
+    "@types/react-dom": "^19.0.3",
+    "typescript": "5.8.2"
+  }
+}

examples/react/next-server-actions-zod/src/app/action.ts

@@ -0,0 +1,39 @@
+'use server'
+
+import {
+  ServerValidateError,
+  createServerValidate,
+} from '@tanstack/react-form-nextjs'
+import { z } from 'zod'
+import { formOpts } from './shared-code'
+
+const schema = z.object({
+  age: z.coerce.number().min(12),
+  firstName: z.string(),
+})
+
+const serverValidate = createServerValidate({
+  ...formOpts,
+  onServerValidate: schema,
+})
+
+export default async function someAction(prev: unknown, formData: FormData) {
+  try {
+    const validatedData = await serverValidate(formData)
+    console.log('validatedData', validatedData)
+    // Persist the form data to the database
+    // await sql`
+    //   INSERT INTO users (name, email, password)
+    //   VALUES (${validatedData.name}, ${validatedData.email}, ${validatedData.password})
+    // `
+  } catch (e) {
+    if (e instanceof ServerValidateError) {
+      return e.formState
+    }
+
+    // Some other error occurred while validating your form
+    throw e
+  }
+
+  // Your form has successfully validated!
+}

examples/react/next-server-actions-zod/src/app/client-component.tsx

@@ -0,0 +1,60 @@
+'use client'
+
+import { useActionState } from 'react'
+import {
+  initialFormState,
+  mergeForm,
+  useForm,
+  useTransform,
+} from '@tanstack/react-form-nextjs'
+import { z } from 'zod'
+import someAction from './action'
+import { formOpts } from './shared-code'
+
+export const ClientComp = () => {
+  const [state, action] = useActionState(someAction, initialFormState)
+
+  const form = useForm({
+    ...formOpts,
+    transform: useTransform(
+      (baseForm) => mergeForm(baseForm, state ?? {}),
+      [state],
+    ),
+  })
+
+  return (
+    <form action={action as never} onSubmit={() => form.handleSubmit()}>
+      <form.Field
+        name="age"
+        validators={{
+          onChange: z.coerce.number().min(8),
+        }}
+      >
+        {(field) => {
+          return (
+            <div>
+              <input
+                name="age"
+                type="number"
+                value={field.state.value}
+                onChange={(e) => field.handleChange(e.target.valueAsNumber)}
+              />
+              {field.state.meta.errors.map((error) => (
+                <p key={error?.message ?? ''}>{error?.message}</p>
+              ))}
+            </div>
+          )
+        }}
+      </form.Field>
+      <form.Subscribe
+        selector={(formState) => [formState.canSubmit, formState.isSubmitting]}
+      >
+        {([canSubmit, isSubmitting]) => (
+          <button type="submit" disabled={!canSubmit}>
+            {isSubmitting ? '...' : 'Submit'}
+          </button>
+        )}
+      </form.Subscribe>
+    </form>
+  )
+}

examples/react/next-server-actions-zod/src/app/layout.tsx

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+import type { Metadata } from 'next'
+
+export const metadata: Metadata = {
+  title: 'Create Next App',
+  description: 'Generated by create next app',
+}
+
+export default function RootLayout({
+  children,
+}: {
+  children: React.ReactNode
+}) {
+  return (
+    <html lang="en">
+      <body>{children}</body>
+    </html>
+  )
+}

examples/react/next-server-actions-zod/src/app/page.tsx

@@ -0,0 +1,9 @@
+import { ClientComp } from './client-component'
+
+export default function Home() {
+  return (
+    <>
+      <ClientComp />
+    </>
+  )
+}

examples/react/next-server-actions-zod/src/app/shared-code.ts

@@ -0,0 +1,8 @@
+import { formOptions } from '@tanstack/react-form-nextjs'
+
+export const formOpts = formOptions({
+  defaultValues: {
+    firstName: '',
+    age: 0,
+  },
+})

examples/react/next-server-actions-zod/tsconfig.json

@@ -0,0 +1,30 @@
+{
+  "compilerOptions": {
+    "target": "es5",
+    "lib": ["DOM", "DOM.Iterable", "ESNext"],
+    "allowJs": true,
+    "skipLibCheck": true,
+    "strict": true,
+    "noEmit": true,
+    "esModuleInterop": true,
+    "module": "ESNext",
+    "moduleResolution": "Bundler",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "jsx": "react-jsx",
+    "incremental": true,
+    "plugins": [
+      {
+        "name": "next"
+      }
+    ]
+  },
+  "include": [
+    "next-env.d.ts",
+    "**/*.ts",
+    "**/*.tsx",
+    ".next/types/**/*.ts",
+    ".next/dev/types/**/*.ts"
+  ],
+  "exclude": ["node_modules"]
+}

examples/react/next-server-actions/package.json

@@ -10,7 +10,7 @@
   "dependencies": {
     "@tanstack/react-form-nextjs": "^1.28.0",
     "@tanstack/react-store": "^0.8.0",
-    "next": "15.5.3",
+    "next": "16.0.5",
     "react": "^19.0.0",
     "react-dom": "^19.0.0"
   },

examples/react/next-server-actions/tsconfig.json

@@ -11,14 +11,20 @@
     "moduleResolution": "Bundler",
     "resolveJsonModule": true,
     "isolatedModules": true,
-    "jsx": "preserve",
+    "jsx": "react-jsx",
     "incremental": true,
     "plugins": [
       {
         "name": "next"
       }
     ]
   },
-  "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],
+  "include": [
+    "next-env.d.ts",
+    "**/*.ts",
+    "**/*.tsx",
+    ".next/types/**/*.ts",
+    ".next/dev/types/**/*.ts"
+  ],
   "exclude": ["node_modules"]
 }