@bits-cr/middy-joi-validator NPM

Middy joi validator middleware

Install

To install middy-joi-validator:

Using NPM:

npm install --save joi @bits-cr/middy-joi-validator

Using yarn:

yarn add joi @bits-cr/middy-joi-validator

Options

inputSchema (Joi.AnySchema object) (optional): The Joi schema object that will be used to validate the input body (request.event.body) of the Lambda handler.
inputValidationOptions (ValidationOptions 'joi') (optional): This can be used to override the options for the joi any.validate method for the input schema. More info: joi.dev - any.validate(value, [options]) . Defaults: Joi defaults options
preserveRawBody (boolean) (optional): This can be used to preserve the original input body at event.rawBody. Defaults: false
inputErrorValidationMessage (string) (optional): This can be used to replace the error message in case of an input schema validation error.
headersSchema (Joi.AnySchema object) (optional): The Joi schema object that will be used to validate the input headers (request.event.headers) of the Lambda handler.
headersValidationOptions (ValidationOptions 'joi') (optional): This can be used to override the options for the joi any.validate method for the headers schema. More info: joi.dev - any.validate(value, [options]) . Defaults: { allowUnknown: true }
preserveRawHeaders (boolean) (optional): This can be used to preserve the original input headers at event.rawHeaders. Defaults: false
headersErrorValidationMessage (string) (optional): This can be used to replace the error message in case of an headers schema validation error.
outputSchema (Joi.AnySchema object) (optional): The Joi schema object that will be used to validate the output (request.response) of the Lambda handler
outputValidationOptions (ValidationOptions 'joi') (optional): This can be used to override the options for the joi any.validate method for the input schema. More info: joi.dev - any.validate(value, [options]) . Defaults: Joi defaults options
outputErrorValidationMessage (string) (optional): This can be used to replace the error message in case of an output schema validation error.

Documentation and examples

//# handler.js #

// import core
import middy from '@middy/core' // esm Node v14+
//const middy = require('@middy/core') // commonjs Node v12+

// import some middlewares
import jsonBodyParser from '@middy/http-json-body-parser'
import httpErrorHandler from '@middy/http-error-handler'
import validator from 'middy-joi-validator'

// import joi
import Joi from 'joi';

// This is your common handler, in no way different than what you are used to doing every day in AWS Lambda
const baseHandler = async (event, context) => {
 // we don't need to deserialize the body ourself as a middleware will be used to do that
 const { creditCardNumber, expiryMonth, expiryYear, cvc, nameOnCard, amount } = event.body

 // do stuff with this data
 // ...

 const response = { result: 'success', message: 'payment processed correctly'}
 return {statusCode: 200, body: JSON.stringify(response)}
}

// Notice that in the handler you only added base business logic (no deserialization,
// validation or error handler), we will add the rest with middlewares

const inputSchema = Joi.object({
  creditCardNumber: Joi.string().min(12).max(19).pattern(/4242424242424242/).required(),
  expiryMonth: Joi.number().integer().min(1).max(12),
  expiryYear: Joi.number().integer().min(2017).max(2027),
  cvc: Joi.string().min(3).max(4),
  nameOnCard: Joi.string(),
  amount: Joi.number()
})

// Let's "middyfy" our handler, then we will be able to attach middlewares to it
const handler = middy(baseHandler)
  .use(jsonBodyParser()) // parses the request body when it's a JSON and converts it to an object
  .use(validator({inputSchema})) // validates the input
  .use(httpErrorHandler()) // handles common http errors and returns proper responses

module.exports = { handler }