Version Router Express

Lightweight api versioning tool for express

Installation

---

npm install --save version-router-express

import:

import {VersionRouter, VersionedRoute} from 'version-router-express';

This module generates Express middleware that enables efficient management of api routes versions. It enables the use of middleware arrays for each version of the route, and flexible version resolving strategies.

Usage

---

Determining the desired version for the request

VersionedRoute assumes the existence of a 'version' property on the request object. This property can be generated in any way along the route's path. VersionedRoute has a static utility method that can be mounted to extract the version from a header and assign it to req.version.

app.use(VersionedRouter.ExtractVersionFromHeader('App-version'));

Any custom header can be used, as well as any other strategy for assigning a value to request.version

Configuring versioned routes

Version matching is done according to semver standards.

const routeVersions = [
  new VersionedRoute({
    version: '1.0.0',
    default: false,
    middleware: [
      (req: Request, res: Response, next: NextFunction) => {
        console.log('route 2 function 1')
        next()
      },
      (req: Request, res: Response, next: NextFunction) => {
        console.log('route 2 function 2')
        res.send({route: '1'})
      },
    ]
  }),
  new VersionedRoute({
    version: '>=1.2.0 <2.0.0',
    default: false,
    middleware: [
      (req: Request, res: Response, next: NextFunction) => {
        console.log('route 2 function 1')
        next()
      },
      (req: Request, res: Response, next: NextFunction) => {
        console.log('route 2 function 2')
        res.send({route: '2'})
      },
    ]
  }),
  new VersionedRoute({
    version: '2.0.0',
    default: true,
    middleware: [
      (req: Request, res: Response, next: NextFunction) => {
        console.log('route 3 function 1')
        next()
      },
      (req: Request, res: Response, next: NextFunction) => {
        console.log('route 3 function 2')
        res.send({route: '3'})
      },
    ]
  })
]

Request version is checked against the versioned route 'version' property according to the semver standard.

If no matches were found, it will resolve to the route defined as default.

Mount VersionRouter

app.use('/testRoute', new VersionRouter(routeVersions).routeRequestByVersion)

The router can be configured with a custom error handler for the version matching stage

app.use('/testRoute', new VersionRouter(
  routeVersions,
  {
    errorHandler: (req, res, next) => {
      // TODO do some error handling stuff
      next(new Error('some message'))
    }
  }).routeRequestByVersion)

Api

---

Class: VersionRouter

Creates a router instance to route requests according to the value of req.version

export declare class VersionRouter

Constructors

Constructor	Description
constructor(routes, options)	Constructs a new instance of the VersionRouter class

Properties

Property	Modifiers	Type	Description
errorHandler		(req: RequestWithVersion, res: Response, next: NextFunction) => void	Error handler function for the version matching stage
routes		Array<VersionedRoute>	Array of VersionedRoute defining the routing options and versions

Methods

Method	Modifiers	Description
ExtractVersionFromHeaders(versionHeader)	static	Middleware for extracting the version from the said request header and assign it to req.version Mount it once BEFORE all versioned routes
routeRequestByVersion()		Middleware to mount on the route path e.g. app.use('/api/users', UsersRoutes.routeRequestByVersion())

Class: VersionedRoute

Creates a versioned route object that contains middleware and version data

Signature:

export declare class VersionedRoute implements VersionedMiddleware 

Implements: VersionedMiddleware

Constructors

Constructor	Description
constructor(config)	Constructs a new instance of the VersionedRoute class

Properties

Property	Modifiers	Type	Description
default		boolean	Sets the version as default.VersionRouterwill resolve to the default route in when version property is undefined or no matching version was found
middleware		Array<RequestHandler>	An array of request handlers to mount on the versioned route
version		string	Semver version number

Methods

Method	Modifiers	Description
toRouter()		returns a Routerinstance with the route's middleware mounted