After Handle

Execute after the main handler, for mapping a returned value of before handle and route handler into a proper response.

It's recommended to use After Handle in the following situations:

• Transform requests into a new value, eg. Compression, Event Stream
• Add custom headers based on the response value, eg. Content-Type

Example

Below is an example of using the after handle to add HTML content type to response headers.

import { Elysia } from 'elysia'
import { isHtml } from '@elysiajs/html'

new Elysia()
    .get('/', () => '<h1>Hello World</h1>', {
        afterHandle({ response, set }) {
            if (isHtml(response))
                set.headers['content-type'] = 'text/html; charset=utf8'
        }
    })
    .get('/hi', () => '<h1>Hello World</h1>')
    .listen(3000)

import { Elysia } from 'elysia'
import { isHtml } from '@elysiajs/html'

new Elysia()
    .get('/', () => '<h1>Hello World</h1>', {
        afterHandle({ response, set }) {
            if (isHtml(response))
                set.headers['content-type'] = 'text/html; charset=utf8'
        }
    })
    .get('/hi', () => '<h1>Hello World</h1>')
    .listen(3000)

The response should be listed as follows:

Path	Content-Type
/	text/html; charset=utf8
/hi	text/plain; charset=utf8

Returned Value

If a value is returned After Handle will use a return value as a new response value unless the value is undefined

The above example could be rewritten as the following:

import { Elysia } from 'elysia'
import { isHtml } from '@elysiajs/html'

new Elysia()
    .get('/', () => '<h1>Hello World</h1>', {
        afterHandle({ response, set }) {
            if (isHtml(response)) {
                set.headers['content-type'] = 'text/html; charset=utf8'
                return new Response(response)
            }
        }
    })
    .get('/hi', () => '<h1>Hello World</h1>')
    .listen(3000)

import { Elysia } from 'elysia'
import { isHtml } from '@elysiajs/html'

new Elysia()
    .get('/', () => '<h1>Hello World</h1>', {
        afterHandle({ response, set }) {
            if (isHtml(response)) {
                set.headers['content-type'] = 'text/html; charset=utf8'
                return new Response(response)
            }
        }
    })
    .get('/hi', () => '<h1>Hello World</h1>')
    .listen(3000)

Unlike beforeHandle, after a value is returned from afterHandle, the iteration of afterHandle will NOT be skipped.

Context

onAfterHandle Context is extends from Context with additional properties of the following:

• response: Response to return to the client

All of the context is based on normal context and can be used like normal context in route handler.