Middy joi validator middleware

middy middleware validator using joi.dev

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 }

Contributing

Everyone is very welcome to contribute to this repository. Feel free to raise issues or to submit Pull Requests.

License

Licensed under MIT License. Copyright (c) 2022 Diego Arce and the Contributors.