Bun.js + Elysia + Drizzle: a type-safe REST API with PostgreSQL

// src/db/schema.ts
import { boolean, pgTable, text, timestamp, uuid } from "drizzle-orm/pg-core";
export const tasks = pgTable("tasks", { id: uuid("id").defaultRandom().primaryKey(), title: text("title").notNull(), done: boolean("done").notNull().default(false), createdAt: timestamp("created_at", { withTimezone: true }).defaultNow().notNull() });
export type Task = typeof tasks.$inferSelect;
export type NewTask = typeof tasks.$inferInsert;

import { Elysia, t } from "elysia";
import { desc, eq } from "drizzle-orm";
import { z } from "zod";
import { db } from "./db/client";
import { tasks } from "./db/schema";
const createTask = z.object({ title: z.string().trim().min(1).max(120) });
export const app = new Elysia()
  .get("/health", () => ({ status: "ok", runtime: "bun" }))
  .get("/tasks", () => db.select().from(tasks).orderBy(desc(tasks.createdAt)))
  .post("/tasks", async ({ body, set }) => { const input = createTask.parse(body); const [task] = await db.insert(tasks).values(input).returning(); set.status = 201; return task; }, { body: t.Object({ title: t.String({ minLength: 1, maxLength: 120 }) }) })
  .patch("/tasks/:id", async ({ params, body }) => { const [task] = await db.update(tasks).set({ done: body.done }).where(eq(tasks.id, params.id)).returning(); return task ?? new Response("Not found", { status: 404 }); }, { params: t.Object({ id: t.String() }), body: t.Object({ done: t.Boolean() }) })
  .listen(Number(Bun.env.PORT ?? 3000));

// src/db/client.ts
import postgres from "postgres";
import { drizzle } from "drizzle-orm/postgres-js";
const sql = postgres(Bun.env.DATABASE_URL!, { max: Number(Bun.env.DB_POOL_SIZE ?? 10), prepare: false });
export const db = drizzle(sql);

services:
  postgres:
    image: postgres:16-alpine
    environment:
      POSTGRES_USER: app
      POSTGRES_PASSWORD: app
      POSTGRES_DB: tasks
    ports: ["5432:5432"]
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U app -d tasks"]

import { expect, test } from "bun:test";
import { app } from "./index";
test("rejects an empty title", async () => {
  const response = await app.handle(new Request("http://localhost/tasks", { method: "POST", headers: { "content-type": "application/json" }, body: JSON.stringify({ title: "  " }) }));
  expect(response.status).toBe(422);
});