AI Prompt: Writing Supabase Edge Functions
How to use
Copy the prompt to a file in your repo.
Use the "include file" feature from your AI tool to include the prompt when chatting with your AI assistant. For example, with GitHub Copilot, use #<filename>, in Cursor, use @Files, and in Zed, use /file.
Prompt
_115---_115# Specify the following for Cursor rules_115description: Coding rules for Supabase Edge Functions_115globs: "supabase/functions/**/*.ts"_115---_115_115# Writing Supabase Edge Functions_115_115You're an expert in writing TypeScript and Deno JavaScript runtime. Generate **high-quality Supabase Edge Functions** that adhere to the following best practices:_115_115## Guidelines_115_1151. Try to use Web APIs and Deno’s core APIs instead of external dependencies (eg: use fetch instead of Axios, use WebSockets API instead of node-ws)_1152. If you are reusing utility methods between Edge Functions, add them to `supabase/functions/_shared` and import using a relative path. Do NOT have cross dependencies between Edge Functions._1153. Do NOT use bare specifiers when importing dependecnies. If you need to use an external dependency, make sure it's prefixed with either `npm:` or `jsr:`. For example, `@supabase/supabase-js` should be written as `npm:@supabase/supabase-js`._1154. For external imports, always define a version. For example, `npm:@express` should be written as `npm:express@4.18.2`._1155. For external dependencies, importing via `npm:` and `jsr:` is preferred. Minimize the use of imports from @`deno.land/x` , `esm.sh` and @`unpkg.com` . If you have a package from one of those CDNs, you can replace the CDN hostname with `npm:` specifier._1156. You can also use Node built-in APIs. You will need to import them using `node:` specifier. For example, to import Node process: `import process from "node:process". Use Node APIs when you find gaps in Deno APIs._1157. Do NOT use `import { serve } from "https://deno.land/std@0.168.0/http/server.ts"`. Instead use the built-in `Deno.serve`._1158. Following environment variables (ie. secrets) are pre-populated in both local and hosted Supabase environments. Users don't need to manually set them:_115 * SUPABASE_URL_115 * SUPABASE_ANON_KEY_115 * SUPABASE_SERVICE_ROLE_KEY_115 * SUPABASE_DB_URL_1159. To set other environment variables (ie. secrets) users can put them in a env file and run the `supabase secrets set --env-file path/to/env-file`_11510. A single Edge Function can handle multiple routes. It is recommended to use a library like Express or Hono to handle the routes as it's easier for developer to understand and maintain. Each route must be prefixed with `/function-name` so they are routed correctly._11511. File write operations are ONLY permitted on `/tmp` directory. You can use either Deno or Node File APIs._11512. Use `EdgeRuntime.waitUntil(promise)` static method to run long-running tasks in the background without blocking response to a request. Do NOT assume it is available in the request / execution context._115_115## Example Templates_115_115### Simple Hello World Function_115_115```tsx_115interface reqPayload {_115 name: string;_115}_115_115console.info('server started');_115_115Deno.serve(async (req: Request) => {_115 const { name }: reqPayload = await req.json();_115 const data = {_115 message: `Hello ${name} from foo!`,_115 };_115_115 return new Response(_115 JSON.stringify(data),_115 { headers: { 'Content-Type': 'application/json', 'Connection': 'keep-alive' }}_115 );_115});_115_115```_115_115### Example Function using Node built-in API_115_115```tsx_115import { randomBytes } from "node:crypto";_115import { createServer } from "node:http";_115import process from "node:process";_115_115const generateRandomString = (length) => {_115 const buffer = randomBytes(length);_115 return buffer.toString('hex');_115};_115_115const randomString = generateRandomString(10);_115console.log(randomString);_115_115const server = createServer((req, res) => {_115 const message = `Hello`;_115 res.end(message);_115});_115_115server.listen(9999);_115```_115_115### Using npm packages in Functions_115_115```tsx_115import express from "npm:express@4.18.2";_115_115const app = express();_115_115app.get(/(.*)/, (req, res) => {_115 res.send("Welcome to Supabase");_115});_115_115app.listen(8000);_115_115```_115_115### Generate embeddings using built-in @Supabase.ai API_115_115```tsx_115const model = new Supabase.ai.Session('gte-small');_115_115Deno.serve(async (req: Request) => {_115 const params = new URL(req.url).searchParams;_115 const input = params.get('text');_115 const output = await model.run(input, { mean_pool: true, normalize: true });_115 return new Response(_115 JSON.stringify(_115 output,_115 ),_115 {_115 headers: {_115 'Content-Type': 'application/json',_115 'Connection': 'keep-alive',_115 },_115 },_115 );_115});_115_115```