Eden Treaty

Eden Treaty is an object representation to interact with a server and features type safety, auto-completion, and error handling.

To use Eden Treaty, first export your existing Elysia server type:

// server.ts
import { Elysia, t } from 'elysia'

const app = new Elysia()
    .get('/hi', () => 'Hi Elysia')
    .get('/id/:id', ({ params: { id } }) => id)
    .post('/mirror', ({ body }) => body, {
        body: t.Object({
            id: t.Number(),
            name: t.String()
        })
    })
    .listen(3000)

export type App = typeof app 

Then import the server type and consume the Elysia API on the client:

// client.ts
import { treaty } from '@elysiajs/eden'
import type { App } from './server'

const app = treaty<App>('localhost:3000')

// response type: 'Hi Elysia'
const { data, error } = await app.hi.get()

Tree like syntax

HTTP Path is a resource indicator for a file system tree.

File system consists of multiple levels of folders, for example:

• /documents/elysia
• /documents/kalpas
• /documents/kelvin

Each level is separated by / (slash) and a name.

However in JavaScript, instead of using "/" (slash) we use "." (dot) to access deeper resources.

Eden Treaty turns an Elysia server into a tree-like file system that can be accessed in the JavaScript frontend instead.

Path	Treaty
/	.index
/hi	.hi
/deep/nested	.deep.nested

Combined with the HTTP method, we can interact with the Elysia server.

Path	Method	Treaty
/	GET	.index.get()
/hi	GET	.hi.get()
/deep/nested	GET	.deep.nested.get()
/deep/nested	POST	.deep.nested.post()

Dynamic path

However, dynamic path parameters cannot be expressed using notation. If they are fully replaced, we don't know what the parameter name is supposed to be.

// ❌ Unclear what the value is supposed to represent?
treaty.item['skadi'].get()

To handle this, we can specify a dynamic path using a function to provide a key value instead.

// ✅ Clear that value is dynamic path is 'name'
treaty.item({ name: 'Skadi' }).get()

Path	Treaty
/item	.item
/item/:name	.item({ name: 'Skadi' })
/item/:name/id	.item({ name: 'Skadi' }).id