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76 changes: 76 additions & 0 deletions website/docs/documentation/connect-on-cloudflare.mdx
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# Using MySQL2 on Cloudflare Workers

This document is a step-by-step tutorial on how to use `node-mysql2` on Cloudflare Workers.

## Prerequisites

Before you try the steps in this document, you need to prepare the following things:

- A [Cloudflare Workers](https://dash.cloudflare.com/login) account.
- [Wrangler](https://developers.cloudflare.com/workers/wrangler/) installed.

If you haven't created a Cloudflare Worker project yet, please refer to [Get Started Guide](https://developers.cloudflare.com/workers/get-started/guide/) to create one.

## Step 1: Configure `wrangler.jsonc` file

Because of the differences between the Cloudflare Workers runtime and the Node.js runtime, you can't use MySQL2 directly on the worker, but you can enable compatibility mode through configuration:

```json
{
"$schema": "node_modules/wrangler/config-schema.json",
"name": "mysql2-cloudflare",
"main": "src/index.ts",
// highlight-start
"compatibility_date": "2025-02-24",
// highlight-end
"observability": {
"enabled": true
},
// highlight-start
"compatibility_flags": ["nodejs_compat"]
// highlight-end
}
```

## Step 2: Disable code generation-based parser

MySQL2 uses code generation based parser for performance by default, but this is restricted on Cloudflare Workers. You may encounter the errors like:

```
Code generation from strings disallowed for this context
```

To make it work, you can disable the code generation-based parser by pass the `disableEval=true` parameter when creating a connection. Here are an example:

```ts
import { createConnection } from 'mysql2/promise';

export default {
async fetch(request, env, ctx): Promise<Response> {
const conn = await createConnection({
host: '<ENTER_HOST>',
port: 3306,
user: '<ENTER_USERNAME>',
password: '<ENTER_PASSWORD>',
// highlight-start
disableEval: true,
// highlight-end
database: '<ENTER_DB_NAME>',
});

const [results] = await conn.query('SHOW TABLES;');

return new Response(JSON.stringify(results));
},
} satisfies ExportedHandler<Env>;
```

:::tip
For some managed MySQL / MySQL-compatible cloud databases (e.g., TiDB Serverless, Planetscale), connections are usually required to use SSL. It is recommended to use the Cloudflare managed connection pool [Hyperdrive](https://developers.cloudflare.com/hyperdrive/) to connect.
:::

## Step 3: Test locally

```
wrangler dev
```