Factory Helper

The Factory Helper provides useful functions for creating Hono's components such as Middleware. Sometimes it's difficult to set the proper TypeScript types, but this helper facilitates that.

Import

npm

import { Hono } from 'hono'
import { createFactory, createMiddleware } from 'hono/factory'

Deno

import { Hono } from 'https://deno.land/x/hono/mod.ts'
import { createFactory, createMiddleware } from 'https://deno.land/x/hono/helper.ts'

createFactory()

createFactory() will create an instance of Factory class.

import { createFactory } from 'hono/factory'

const factory = createFactory()

You can pass your Env types as Generics:

type Env = {
  Variables: {
    foo: string
  }
}

const factory = createFactory<Env>()

createMiddleware()

createMiddleware() is shortcut of factory.createMiddleware(). This function will create your custom middleware.

const messageMiddleware = createMiddleware(async (c, next) => {
  await next()
  c.res.headers.set('X-Message', 'Good morning!')
})

Tip: If you want to get an argument like message, you can create it as a function like the following.

const messageMiddleware = (message: string) => {
  return createMiddleware(async (c, next) => {
    await next()
    c.res.headers.set('X-Message', message)
  })
}

app.use(messageMiddleware('Good evening!'))

factory.createHandlers() Experimental

This function helps to define handlers in a different place than app.get('/').

import { createFactory } from 'hono/factory'
import { logger } from 'hono/logger'

// ...

const factory = createFactory()

const middleware = factory.createMiddleware(async (c, next) => {
  c.set('foo', 'bar')
  await next()
})

const handlers = factory.createHandlers(logger(), middleware, (c) => {
  return c.json(c.var.foo)
})

app.get('/api', ...handlers)