Swagger Express Middleware

Swagger middlware and mocks for Express.js and Node

Validate Request middleware

Ensures that every request complies with your Swagger API definition, or returns the appropriate HTTP error codes if needed. Of course, you can catch any validation errors and handle them however you want.

Example

This example uses the PetStore.yaml sample Swagger API. If you aren’t familiar with using middleware in Express.js, then read this first.

const express = require('express');
const createMiddleware = require('swagger-express-middleware');

let app = express();

createMiddleware('PetStore.yaml', app, function(err, middleware) {
    app.use(middleware.metadata());
    app.use(middleware.parseRequest());
    app.use(middleware.validateRequest());

    // An HTML page to help you produce a validation error
    app.use(function(req, res, next) {
        res.send(
            'Click this button to see a validation error:' +
            '<form action="/pets/Fido" method="post">' +
            '<button type="submit">POST</button>' +
            '</form>'
        );
    });

    // Error handler to display the validation error as HTML
    app.use(function(err, req, res, next) {
        res.status(err.status);
        res.send(
            '<h1>' + err.status + ' Error</h1>' +
            '<pre>' + err.message + '</pre>'
        );
    });

    app.listen(8000, function() {
        console.log('Go to http://localhost:8000');
    });
});

Run the above example and then browse to http://localhost:8000. When you click the button, it will send a POST request to the /pets/{petName} path in the Swagger PetStore API. However, that path does not allow POST requests, so the Validate Request middleware will throw an HTTP 405 (Method Not Allowed) error.

Options

middleware.validateRequest(router)

This is the function you call to create the Validate Request middleware.

Dependencies

The Validate Request middleware requires the following middleware to come before it in the middleware pipeline (as shown in the example above):

Behavior

The Validate Request middleware checks each HTTP request for several different things and throws the appropriate HTTP error if validation fails. You can then handle the error by adding your own own error-handling middleware. You might choose to respond with a friendly error message, or you may choose to ignore the error and allow the request to continue being processed as normal. Be careful if you decide to continue processing - depending on how invalid the HTTP request is, it may cause other errors in other middleware.

HTTP 401 (Unauthorized)

If your Swagger API has security requirements defined, then the Validate Request middleware will check to make sure each request contains the necessary security info. For example, if you’re using basic security, then it will verify that the Authorization HTTP header is present. If you’re using apiKey security, then it will verify that the corresponding HTTP header or query parameter exists.

If the request doesn’t contain the necessary security information, then it will throw an HTTP 401 (Unauthorized) error. For basic security, it will also set the WWW-Authenticate response header.

NOTE: The Validate Request middleware does not perform any authentication or authorization. It simply verifies that authentication info is present.

HTTP 404 (Not Found)

The Validate Request middleware will throw an HTTP 404 (Not Found) error for any request that doesn’t match one of the paths in your Swagger API. If your API has a basePath specified, then the Validate Request middleware will only validate requests that are within the base path. So it will not throw a 404 for requests that are outside of the base path.

HTTP 405 (Method Not Allowed)

If the HTTP request method does not match one of the methods allowed by your Swagger API, then the Validate Request middleware will throw an HTTP 405 (Method Not Allowed) error. For example, if your Swagger API has a /pets/{petName} path with GET, POST, and DELETE operations, and somebody sends a PATCH /pets/Fido request, then a 405 error will be thrown.

In addition, the Allow response header will be set to the methods that are allowed by your Swagger API.

HTTP 406 (Not Acceptable)

If your Swagger API includes a produces list of MIME types that your API can produce, then the Validate Request middleware will check the Accept header of incoming requests to make sure the client accepts at least one of your MIME types. If none of your MIME types are accepted, then an HTTP 406 (Not Acceptable) error is thrown.

HTTP 413 (Request Entity Too Large)

If the request includes a payload (an HTTP body or form-data), and your Swagger operation does not have any body or formData parameters defined, then an HTTP 413 (Request Entity Too Large) error is thrown.

HTTP 415 (Unsupported Media Type)

If your Swagger API includes a consumes list of MIME types that your API can consume, then the Validate Request middleware will check the Content-Type header of incoming requests to make sure it matches one of your MIME types. If the content does not match any of your MIME types, then an HTTP 415 (Unsupported Media Type) is thrown.

HTTP 500 (Internal Server Error)

If there’s an error in the Swagger API itself — for example, the file couldn’t be found, couldn’t be parsed, or is invalid — then the Validate Request middleware will throw an HTTP 500 (Internal Server Error) error.