middy-ajv

    2.0.0 • Public • Published

    Middy AJV

    Middy logo

    AJV middleware for the middy framework, the stylish Node.js middleware engine for AWS Lambda

    This middleware automatically validates incoming events and outgoing responses against custom schemas defined with the JSON schema syntax.

    If an incoming event fails validation a BadRequest error is raised. If an outgoing response fails validation a InternalServerError error is raised.

    This middleware can be used in combination with httpErrorHandler to automatically return the right response to the user.

    It can also be used in combination with httpcontentnegotiation to load localised translations for the error messages (based on the currently requested language). This feature uses internally ajv-i18n module, so reference to this module for options and more advanced use cases. By default the language used will be English (en), but you can redefine the default language by passing it in the ajvOptions options with the key defaultLanguage and specifying as value one of the supported locales.

    Also, this middleware accepts an object with plugins to be applied to customize the internal ajv instance. Out-of-the-box ajv-i18n and ajv-formats are being used.

    Install

    To install this middleware you can use NPM:

    npm install --save middy-ajv

    Requires: @middy/core:>=2.0.0

    Options

    • inputSchema (object) (optional): The JSON schema compiled ajv validator that will be used to validate the input (request.event) of the Lambda handler.
    • outputSchema (object) (optional): The JSON schema compiled ajv validator that will be used to validate the output (request.response) of the Lambda handler.
    • availableLanguages (object) (optional): Error messages can be returned in multiple languages using ajv-i18n. Language is selected based on event.preferredLanguage set by @middy/http-content-negotiation. Should be in the format: { 'en': require('ajv-i18n/localize/en') }.
    • defaultLanguage (string) (default: en): The default language to use when availableLanguages is provided and event.preferredLanguage is not supported.

    NOTES:

    • At least one of inputSchema or outputSchema is required.

    Sample usage

    Example for validation using precompiled schema:

    import middy from '@middy/core'
    import validator from 'middyajv'
    
    const handler = middy((event, context) => {
      return {}
    })
    
    const inputSchema = require('schema.js')
    
    handler.use(validator({ inputSchema }))
    
    // invokes the handler, note that property foo is missing
    const event = {
      body: JSON.stringify({something: 'somethingelse'})
    }
    handler(event, {}, (err, res) => {
      t.is(err.message,'Event object failed validation')
    })

    Example for validation that will compile the schema before deploying:

    import middy from '@middy/core'
    import validator from '@middy/validator' // We use the more developer friendly middeware, with place of replacing during build
    
    const handler = middy((event, context) => {
      return {}
    })
    
    const schema = require('schema.json')
    
    handler.use(validator({ inputSchema }))
    
    // invokes the handler, note that property foo is missing
    const event = {
      body: JSON.stringify({something: 'somethingelse'})
    }
    handler(event, {}, (err, res) => {
      t.is(err.message,'Event object failed validation')
    })

    Build step

    Folder Structure

    {project}
    |-- handlers
    | |-- {enpoint}
    | | |-- index.mjs
    | | |-- schema.json

    After the build scripts have been run the endpoint folder will contain schema.js and index.js. The later of which you need to upload to AWS.

    Install

    $ npm install -D ajv-cli rollup @rollup/plugin-commonjs @rollup/plugin-json @rollup/plugin-node-resolve @rollup/plugin-replace rollup-plugin-esbuild esbuild

    rollup.config.js

    import { readdirSync } from 'fs'
    import commonjs from '@rollup/plugin-commonjs'
    import json from '@rollup/plugin-json'
    import resolve from '@rollup/plugin-node-resolve'
    import replace from '@rollup/plugin-replace'
    import esbuild from 'rollup-plugin-esbuild'
    
    function onwarn (warning, warn) {
      if (warning.code === 'CIRCULAR_DEPENDENCY') return
      warn(warning)
    }
    
    import {dirname, join} from 'path'
    const handlers = readdirSync('./handlers').filter((dir) => dir !=='.DS_Store')
    export default handlers.map((input) => ({
      input: 'handlers/' + input + '/index.mjs',
      output: {
        file: 'handlers/' + input + '/index.js',
        format: 'cjs',
      },
      plugins: [
        replace({
          preventAssignment: false,  // remove warning, will be default in future version
          delimiters: ['',''],
          include: ['./**/index.mjs'],
          values: {
            // use leaner version of `@middy/validator`
            'require(\'@middy/validator\')': 'require(\'middy-ajv\')',
            'from \'@middy/validator\'': 'from \'middy-ajv\'',
    
            // use compiled schemas for `middy-ajv`
            'require(\'./schema.json\')': 'require(\'./schema.js\').default',
            'inputSchema from \'./schema.json\'': 'inputSchema from \'./schema.js\'',
          }
        }),
        json(),
        resolve({ preferBuiltins: true }),
        commonjs(),
        esbuild({
          minify: true,
          target: 'es2020'
        })
      ],
      external: [
        'aws-sdk',
        'aws-sdk/clients/cloudfront', 'aws-sdk/clients/waf', 'aws-sdk/clients/s3',
        'aws-sdk/clients/ssm', 'aws-sdk/clients/sns', 'aws-sdk/clients/sqs', 'aws-sdk/clients/stepfunctions',
        'aws-sdk/clients/dynamodb', 'aws-sdk/clients/rds'
      ],
      onwarn,
    }))

    Run

    # Compile JSON Schemas
    $ for dir in handlers/*/; do node ./node_modules/ajv-cli/dist/index.js compile -c ajv-formats -c ajv-formats-draft2019 --strict=true --coerce-types=array --all-errors=true --use-defaults=empty --messages=false -s $dir'schema.json' -o $dir'schema.js'; done
    # Bundle
    $ rollup --config rollup.config.js --environment INCLUDE_DEPS,BUILD:production

    Middy documentation and examples

    For more documentation and examples, refers to the main Middy monorepo on GitHub or Middy official website.

    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) 2017-2021 will Farrell and the Middy team.

    FOSSA Status

    Install

    npm i middy-ajv

    DownloadsWeekly Downloads

    1

    Version

    2.0.0

    License

    MIT

    Unpacked Size

    12.1 kB

    Total Files

    4

    Last publish

    Collaborators

    • willfarrell