Skip to main content

Getting started

Install​

To install middy, you can use NPM:

npm install --save @middy/core

If you are using TypeScript, you will also want to make sure that you have installed the @types/aws-lambda peer-dependency:

npm install --save-dev @types/aws-lambda

Usage​

As you will see in the next example, using middy is very simple and requires just few steps:

  1. Write your Lambda handlers as usual, focusing mostly on implementing the bare business logic for them.
  2. Import middy and all the middlewares you want to use.
  3. Wrap your handler in the middy() factory function. This will return a new enhanced instance of your original handler, to which you will be able to attach the middlewares you need.
  4. Attach all the middlewares you need using the function .use(somemiddleware())

Example​

import middy from '@middy/core'
import middleware1 from 'sample-middleware1'
import middleware2 from 'sample-middleware2'
import middleware3 from 'sample-middleware3'

const lambdaHandler = (event, context) => {
  /* your business logic */
}

export const handler = middy()
  .use(middleware1())
  .use(middleware2())
  .use(middleware3())
  .handler(lambdaHandler)

.use() takes a single middleware or an array of middlewares, so you can attach multiple middlewares in a single call:

import middy from '@middy/core'
import middleware1 from 'sample-middleware1'
import middleware2 from 'sample-middleware2'
import middleware3 from 'sample-middleware3'

const lambdaHandler = (event, context) => {
  /* your business logic */
}

export const handler = middy()
  .use([middleware1(), middleware2(), middleware3()])
  .handler(lambdaHandler)

You can also attach inline middlewares by using the functions .before, .after and .onError.

For a more detailed use case and examples check the Writing a middleware section.