Swagger Express Validator

swagger-express-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

• express ^4.0.0
• 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-express-validator --save

Sample use

To set up simple validation for your requests and responses:

1const util = require('util');
2const express = require('express');
3const bodyParser = require('body-parser');
4const validator = require('swagger-express-validator');
5const schema = require('./api-schema.json');
6
7const server = express();
8server.use(bodyParser.json());
9
10const opts = {
11  schema, // Swagger schema
12  preserveResponseContentType: false, // Do not override responses for validation errors to always be JSON, default is true
13  returnRequestErrors: true, // Include list of request validation errors with response, default is false
14  returnResponseErrors: true, // Include list of response validation errors with response, default is false
15  validateRequest: true,
16  validateResponse: true,
17  requestValidationFn: (req, data, errors) => {
18    console.log(`failed request validation: ${req.method} ${req.originalUrl}\n ${util.inspect(errors)}`)
19  },
20  responseValidationFn: (req, data, errors) => {
21    console.log(`failed response validation: ${req.method} ${req.originalUrl}\n ${util.inspect(errors)}`)
22  },
23};
24server.use(validator(opts));
25
26server.use('/status', (req, res) => {
27  res.json({
28    status: 'OK',
29  })
30});
31server.use((err, req, res, next) => {
32  res.status(500);
33  res.json(err);
34});
35
36return server.listen(3000);
37

Ajv configuration

swagger-express-validator uses Ajv for schema validation under the hood. You can tweak many validation parameters by passing Ajv configuration overrides:

1server.use(validator({
2  schema,
3  preserveResponseContentType: false,
4  returnRequestErrors: true,
5  returnResponseErrors: true,
6  validateRequest: true,
7  validateResponse: true,
8  ajvRequestOptions: {
9    coerceTypes: true,
10  },
11  ajvResponseOptions: {
12    coerceTypes: true,
13  },
14}));

See Ajv documentation for supported values.

Debugging

To see debug output use DEBUG=swagger-express-validator as an environmental variable when starting your project, eg.: DEBUG=swagger-express-validator node server.js. To gain more insights on how this works see documentation of debug library

Contributors

• Naz
• Isaac Stefanek
• James Gregory
• Igor Savin

Licence

MIT

Special thanks to @bgaluszka for initial inspiration :)