Package Exports

express-openapi-validator

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Readme

express-openapi-validator

An OpenApi validator for ExpressJS that automatically validates API requests using an OpenAPI 3.0 specification.

express-openapi-validator is unopinionated and does not impose any coding convention or project structure. Simply, install the validator onto your express app, then define and implement routes the way you prefer. See an example.

Install

npm i express-openapi-validator

Usage

Install the openapi validator

new OpenApiValidator({
  apiSpecPath: './openapi.yaml',
}).install(app);

Then, register an error handler to customize errors

app.use((err, req, res, next) => {
  // format error
  res.status(err.status).json({
    errors: err.errors,
  });
});

Example Express API Server

Try the complete example below:

var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var logger = require('morgan');
var http = require('http');
var OpenApiValidator = require('express-openapi-validator').OpenApiValidator;
var app = express();

app.use(bodyParser.json());
app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

new OpenApiValidator({
  apiSpecPath: './openapi.yaml',
}).install(app);

app.get('/v1/pets', function(req, res, next) {
  res.json([{ id: 1, name: 'max' }, { id: 2, name: 'mini' }]);
});

app.post('/v1/pets', function(req, res, next) {
  res.json({ name: 'sparky' });
});

app.get('/v1/pets/:id', function(req, res, next) {
  res.json({ id: req.params.id, name: 'sparky' });
});

// Register error handler
app.use((err, req, res, next) => {
  // format error
  res.status(err.status).json({
    errors: err.errors,
  });
});

var server = http.createServer(app);
server.listen(3000);
console.log('Listening on port 3000');

module.exports = app;

Example Express API Server (clone it)

A fully working example lives here

Example validation responses

Validate a query parameter with a value constraint

/pets/:id should be of type integer, express-openapi-validator returns:

curl http://localhost:3000/v1/pets/as |jq
{
  "errors": [
    {
      "path": "id",
      "errorCode": "type.openapi.validation",
      "message": "should be integer",
      "location": "path"
    }
  ]
}

Validate a query parameter with a range constraint

/pets?limit=? should be of type integer with a value greater than 5, express-openapi-validator returns:

curl http://localhost:3000/v1/pets?limit=1 |jq
{
  "errors": [
    {
      "path": "limit",
      "errorCode": "minimum.openapi.validation",
      "message": "should be >= 5",
      "location": "query"
    },
    {
      "path": "test",
      "errorCode": "required.openapi.validation",
      "message": "should have required property 'test'",
      "location": "query"
    }
  ]
}

Validate the query parameter's value type

POST /pets is defined to only accept media type application/json, express-openapi-validator returns:

curl --request POST \
  --url http://localhost:3000/v1/pets \
  --header 'content-type: application/xml' \
  --data '{
        "name": "test"
}' |jq
{
  "errors": [
    {
      "message": "Unsupported Content-Type application/xml"
    }
  ]
}

Validate a POST body to ensure required parameters are present

POST /pets request body is required to contain the name properly, express-openapi-validator returns:

λ  my-test curl --request POST \
  --url http://localhost:3000/v1/pets \
  --header 'content-type: application/json' \
  --data '{
}'|jq
  "errors": [
    {
      "path": "name",
      "errorCode": "required.openapi.validation",
      "message": "should have required property 'name'",
      "location": "body"
    }
  ]
}

...and much more. Try it out!

License

MIT