ajv-openapi-compile

ajv-openapi-compile

Given an OpenAPI definition, compile into AJV validation modules to be used in environments (like Cloudflare Workers) where eval is not available, or a single JavaScript file is desired.

Install

The normal way:

npm install ajv-openapi-compile --save-dev

Build With It

You can use the CLI tool, as part of your build process:

ajv-openapi-compile --definition=/path/to/openapi.json \
  --output=/path/to/compiled.js \
  --tree=/path/to/tree.js

You can also use in your build scripts:

import { compile } from 'ajv-openapi-compile'
import { readFile, writeFile } from 'node:fs'
const definition = JSON.parse(await readFile('/path/to/openapi.json', 'utf8'))
const { code, tree } = await compile(definition)
await writeFile('/path/to/compiled.js', code, 'utf8')
await writeFile('/path/to/tree.js', tree, 'utf8')

The output from the compile function contains the code property, which has all imports/requires resolved and concatenated into the single string.

Use Built Code

The compiled code is an ES string, and exports schema as the default, which is a map of schema identifiers to validation functions.

If you know the fully-resolved schema id, you can access the validation function explicitly:

import schemas from '/path/to/compiled.js'
const validate = schemas['#/components/schema/error']
const valid = validate({ code: 404 })
if (!valid) console.log(validate.errors)

Note: The schema identifiers are escaped using the JSON Pointer (RFC6901) specs, which turns ~ into ~0 and / into ~1.

If you don't know the fully-resolved schema id, you can use something like pointer-props to navigate the structure and resolve to the correct id:

import { resolve, toPointer } from 'pointer-props'
import { readFile } from 'node:fs'
import schemas from '/path/to/compiled.js'
const definition = JSON.parse(await readFile('/path/to/openapi.json', 'utf8'))
// lookup the id
const id = resolve(definition, '#/path/to/schema') // => '/path/to/fully/resolved/schema'
// note the relative reference requires "#" as the prefix
const validate = schemas['#' + id]
const valid = validate({ code: 404 })
if (!valid) console.log(validate.errors)

CLI ajv-openapi-compile

The CLI takes the following parameters:

• ---definition, -d (String) - The path to the definition JSON file.
• ---output, -o (String) - The path to write the compiled AJV validation code.

For convenience and compatability with other tooling, the definition parameter also supports importing JavaScript files, and will follow this algorithm:

• If the file extension is .json read and parse as JSON
• If the file extension is .yaml or .yml read and parse as YAML (using js-yaml internally)
• Otherwise, attempt importing * as schema
• If schema.definition is set, use that
• Otherwise, try using schema
• Otherwise, try importing the default as schema and try that

To be considered valid, the imported schema definition must have a paths object, with at least one "Path Object" defined.

API: function(definition: Object) => { code: String }

The function simply takes a valid OpenAPI 3.x object.

It returns an object with the following properties:

• code: String - The compiled code, with all import and require statements resolved and placed inline.

License

Published and released under the Very Open License.

If you need a commercial license, contact me here.