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201 changes: 201 additions & 0 deletions docs/docs/00100-intro/00200-quickstarts/00150-nextjs.md
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---
title: Next.js Quickstart
sidebar_label: Next.js
slug: /quickstarts/nextjs
hide_table_of_contents: true
---

import { InstallCardLink } from "@site/src/components/InstallCardLink";
import { StepByStep, Step, StepText, StepCode } from "@site/src/components/Steps";


Get a SpacetimeDB Next.js app running in under 5 minutes.

## Prerequisites

- [Node.js](https://nodejs.org/) 18+ installed
- [SpacetimeDB CLI](https://spacetimedb.com/install) installed

<InstallCardLink />

---

<StepByStep>
<Step title="Create your project">
<StepText>
Run the `spacetime dev` command to create a new project with a SpacetimeDB module and Next.js client.

This will start the local SpacetimeDB server, publish your module, generate TypeScript bindings, and start the Next.js development server.
</StepText>
<StepCode>
```bash
spacetime dev --template nextjs-ts my-nextjs-app
```
</StepCode>
</Step>

<Step title="Open your app">
<StepText>
Navigate to [http://localhost:3001](http://localhost:3001) to see your app running.

Note: The Next.js dev server runs on port 3001 to avoid conflict with SpacetimeDB on port 3000.
</StepText>
</Step>

<Step title="Explore the project structure">
<StepText>
Your project contains both server and client code using the Next.js App Router.

Edit `spacetimedb/src/index.ts` to add tables and reducers. Edit `app/page.tsx` to build your UI.
</StepText>
<StepCode>
```
my-nextjs-app/
├── spacetimedb/ # Your SpacetimeDB module
│ └── src/
│ └── index.ts # Server-side logic
├── app/ # Next.js App Router
│ ├── layout.tsx # Root layout with providers
│ ├── page.tsx # Home page
│ └── providers.tsx # SpacetimeDB provider (client component)
├── src/
│ └── module_bindings/ # Auto-generated types
└── package.json
```
</StepCode>
</Step>

<Step title="Understand tables and reducers">
<StepText>
Open `spacetimedb/src/index.ts` to see the module code. The template includes a `person` table and two reducers: `add` to insert a person, and `say_hello` to greet everyone.

Tables store your data. Reducers are functions that modify data — they're the only way to write to the database.
</StepText>
<StepCode>
```typescript
import { schema, table, t } from 'spacetimedb/server';

export const spacetimedb = schema(
table(
{ name: 'person', public: true },
{
name: t.string(),
}
)
);

spacetimedb.reducer('add', { name: t.string() }, (ctx, { name }) => {
ctx.db.person.insert({ name });
});

spacetimedb.reducer('say_hello', (ctx) => {
for (const person of ctx.db.person.iter()) {
console.info(`Hello, ${person.name}!`);
}
console.info('Hello, World!');
});
```
</StepCode>
</Step>

<Step title="Test with the CLI">
<StepText>
Use the SpacetimeDB CLI to call reducers and query your data directly.
</StepText>
<StepCode>
```bash
# Call the add reducer to insert a person
spacetime call my-nextjs-app add Alice

# Query the person table
spacetime sql my-nextjs-app "SELECT * FROM person"
name
---------
"Alice"

# Call say_hello to greet everyone
spacetime call my-nextjs-app say_hello

# View the module logs
spacetime logs my-nextjs-app
2025-01-13T12:00:00.000000Z INFO: Hello, Alice!
2025-01-13T12:00:00.000000Z INFO: Hello, World!
```
</StepCode>
</Step>

<Step title="Understand the provider pattern">
<StepText>
SpacetimeDB is client-side only — it cannot run during server-side rendering. The `app/providers.tsx` file uses the `"use client"` directive and wraps your app with `SpacetimeDBProvider`.

The template uses environment variables for configuration. Set `NEXT_PUBLIC_SPACETIMEDB_URI` and `NEXT_PUBLIC_SPACETIMEDB_MODULE` to override defaults.
</StepText>
<StepCode>
```tsx
// app/providers.tsx
'use client';

import { useMemo } from 'react';
import { SpacetimeDBProvider } from 'spacetimedb/react';
import { DbConnection } from '../src/module_bindings';

const URI = process.env.NEXT_PUBLIC_SPACETIMEDB_URI ?? 'ws://localhost:3000';
const MODULE = process.env.NEXT_PUBLIC_SPACETIMEDB_MODULE ?? 'my-nextjs-app';

export function Providers({ children }: { children: React.ReactNode }) {
const connectionBuilder = useMemo(() =>
DbConnection.builder()
.withUri(URI)
.withModuleName(MODULE),
[]
);

return (
<SpacetimeDBProvider connectionBuilder={connectionBuilder}>
{children}
</SpacetimeDBProvider>
);
}
```
</StepCode>
</Step>

<Step title="Use React hooks for data">
<StepText>
In your page components, use `useTable` to subscribe to table data and `useReducer` to call reducers. All components using these hooks must have the `"use client"` directive.
</StepText>
<StepCode>
```tsx
// app/page.tsx
'use client';

import { tables, reducers } from '../src/module_bindings';
import { useTable, useReducer } from 'spacetimedb/react';

export default function Home() {
// Subscribe to table data - returns [rows, isLoading]
const [people] = useTable(tables.person);

// Get a function to call a reducer
const addPerson = useReducer(reducers.add);

const handleAdd = () => {
// Call reducer with object syntax
addPerson({ name: 'Alice' });
};

return (
<ul>
{people.map((person, i) => <li key={i}>{person.name}</li>)}
</ul>
);
}
```
</StepCode>
</Step>
</StepByStep>

## Next steps

- See the [Chat App Tutorial](/tutorials/chat-app) for a complete example
- Read the [TypeScript SDK Reference](/sdks/typescript) for detailed API docs
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