Elysia

Build a REST API with Elysia and jcell. Elysia is a performant Bun-first web framework with end-to-end type safety.

Setup

bun add @sajjadbzn/jcell elysia

Complete API

app.ts

import { Elysia, t as elysiaT } from 'elysia'
import { createDB, schema, t, fileAdapter } from '@sajjadbzn/jcell'

// ── Schema ─────────────────────────────────────────────────────────────────

const taskSchema = schema({
  id: t.id(),
  title: t.string(),
  completed: t.boolean().default(false),
  priority: t.enum(['low', 'medium', 'high'] as const),
  createdAt: t.date().default(() => new Date()),
})

// ── Database setup ─────────────────────────────────────────────────────────

const db = createDB({ adapter: fileAdapter({ path: './data' }) })
const tasks = db.collection('tasks', taskSchema)

// ── Elysia app ─────────────────────────────────────────────────────────────

const app = new Elysia()
  .get('/tasks', async () => {
    return await tasks.find()
  })

  .post(
    '/tasks',
    async ({ body }) => {
      try {
        const task = await tasks.insert({
          title: body.title,
          priority: body.priority ?? 'medium',
        })
        return task
      } catch (err) {
        return { error: (err as Error).message }
      }
    },
    {
      body: elysiaT.Object({
        title: elysiaT.String(),
        priority: elysiaT.Optional(
          elysiaT.Union([
            elysiaT.Literal('low'),
            elysiaT.Literal('medium'),
            elysiaT.Literal('high'),
          ]),
        ),
      }),
    },
  )

  .patch('/tasks/:id', async ({ params, body }) => {
    const count = await tasks.update({ id: params.id }, body)
    if (count === 0) return { error: 'Not found' }
    return await tasks.first({ id: params.id })
  })

  .delete('/tasks/:id', async ({ params }) => {
    const count = await tasks.delete({ id: params.id })
    if (count === 0) return { error: 'Not found' }
    return { deleted: true }
  })

  .listen(3000)

console.log(`Elysia + jcell running at http://localhost:${app.server?.port}`)

Run It

bun run app.ts

Type Safety

Elysia's validation integrates with Elysia's built-in type system for request validation:

.post(
  '/tasks',
  async ({ body }) => {
    // body.title is typed as string
    // body.priority is typed as 'low' | 'medium' | 'high' | undefined
    const task = await tasks.insert({
      title: body.title,
      priority: body.priority,
    })
    return task
  },
  {
    body: elysiaT.Object({
      title: elysiaT.String(),
      priority: elysiaT.Optional(
        elysiaT.Union([
          elysiaT.Literal('low'),
          elysiaT.Literal('medium'),
          elysiaT.Literal('high'),
        ]),
      ),
    }),
  },
)