Swagger Koa Validator

swagger-koa-validator is a lightweight middleware for request/response validation based on OpenAPI v2.0 (aka swagger) specification.

The main difference of this package to alternatives like swagger-tools is that this package is very configurable and only concentrates on validation against provided schema. You can choose the behavior of invalid validation like returning a 500 or just logging an error to your logger.

Requirements

• koa ^2.0.0
• body-parser ^1.0.0

Features

• Configurable validation behavior
• Fastest available JSON schema validation based on ajv library
• Optional validations for either request parameters or response values
• Independent from express application structure. This is a simple drop-in middleware without additional alterations to your swagger definitions or application routing.
• Support for nullable field validation though x-nullable attribute

Installation

Start using this library with npm install swagger-koa-validator --save

Sample use

To set up simple validation for your requests and responses:

const util = require('util');
const koa = require('koa');
const bodyParser = require('body-parser');
const validator = require('swagger-koa-validator');
const schema = require('./api-schema.json');

const server = koa();
server.use(bodyParser.json());

const opts = {
  schema, // Swagger schema
  preserveResponseContentType: false, // Do not override responses for validation errors to always be JSON, default is true
  returnRequestErrors: true, // Include list of request validation errors with response, default is false
  returnResponseErrors: false, // Include list of response validation errors with response, default is false
  validateRequest: true,
  validateResponse: false,
  requestValidationFn: (req, data, errors, res) => {
    console.log(`failed request validation: ${req.method} ${req.originalUrl}\n ${util.inspect(errors)}`)
    res.validator_errors = errors
  },
  responseValidationFn: (req, data, errors, res) => {
    console.log(`failed response validation: ${req.method} ${req.originalUrl}\n ${util.inspect(errors)}`)
  },
};
server.use(validator(opts));

server.use((ctx, next) => {
  if(ctx.response.validator_errors) return ctx.body = {
    error:"Validation Error", 
    errors:ctx.response.validator_errors
  }
});

return server.listen(3000);

Contributors

• Nazar Gargol
• Isaac Stefanek
• James Gregory
• Igor Savin
• Danila Plee

Licence

MIT