Guard

When you need to apply multiple hooks to your application, instead of repeating hooks multiple times, you can use guard to bulk add hooks to your application.

import { Elysia, t } from 'elysia'

new Elysia()
  .onBeforeHandle(({ query: { name }, status }) => {
    if(!name) return status(401)
  })
  .onBeforeHandle(({ query: { name } }) => {
    console.log(name)
  })
  .onAfterResponse(({ responseValue }) => {
    console.log(responseValue)
  })
  .guard({
    beforeHandle: [
      ({ query: { name }, status }) => {
        if(!name) return status(401)
      },
      ({ query: { name } }) => {
        console.log(name)
      }
    ],
    afterResponse({ responseValue }) {
      console.log(responseValue)
    }
  })
  .get(
    '/auth',
    {
      query: t.Object({
        name: t.String()
      })
    }, ({ query: { name = 'anon' } }) => `Hello ${name}!`
  )
  .get(
    '/profile',
    {
      query: t.Object({
        name: t.String()
      })
    }, ({ query: { name = 'anon' } }) => `Hello ${name}!`
  )
  .listen(3000)

Not only that, you can also apply schema to multiple routes using guard.

import { Elysia, t } from 'elysia'

new Elysia()
  .guard({
    beforeHandle: [
      ({ query: { name }, status }) => {
        if(!name) return status(401)
      },
      ({ query: { name } }) => {
        console.log(name)
      }
    ],
    afterResponse({ responseValue }) {
      console.log(responseValue)
    },
    query: t.Object({
      name: t.String()
    })
  })
  .get(
    '/auth',
    {
      query: t.Object({
        name: t.String()
      })
    }, ({ query: { name = 'anon' } }) => `Hello ${name}!`
  )
  .get(
    '/profile',
    {
      query: t.Object({
        name: t.String()
      })
    }, ({ query: { name = 'anon' } }) => `Hello ${name}!`
  )
  .listen(3000)

This will apply hooks and schema to every route after .guard is called in the same instance.

See Guard for more information.

Assignment

Let’s put 2 types of hooks into practice.

Assignments

0 of 2 assignments passed

Authentication
Not passed yet
Let's add a simple authentication middleware to GET "/auth" endpoint using beforeHandle hook. If query `name` is provided, we will let the request pass, otherwise we will return 401 status.
Interceptor hook
Not passed yet
Now, let's create another endpoint GET "/profile" that has the same logic with authentication. We can refactor our code by using interceptor hook to avoid duplication.

We can use beforeHandle to intercept the request before it reaches the handler, and return a response with status method.

import { Elysia } from 'elysia'

new Elysia()
  .onBeforeHandle(({ query: { name }, status }) => {
    if(!name) return status(401)
  })
  .get('/auth', ({ query: { name = 'anon' } }) => {
    return `Hello ${name}!`
  })
  .get('/profile', ({ query: { name = 'anon' } }) => {
    return `Hello ${name}!`
  })
  .listen(3000)

One sec, warming things up…

Authentication

Interceptor hook