Following on from my previous article: Create REST API from your database in minute with Feathers.js, today I want to add a UI to explore the Feathers.js API.

When we provide an API, it’s common to make a tool available to explore the exposed methods.
Swagger UI is one such tool, and fortunately, in the Feathers.js ecosystem, a package is available for this purpose.

First step: install and declare the package

In my previous article, I created a Feathers.js project using Koa as HTTP framework, TypeScript as language and NPM as package manager. To install the feathers-swagger package, I use the command :

npm install feathers-swagger swagger-ui-dist koa-mount koa-static

Once I’ve installed the necessary packages, I just need to declare the Swagger interface in my project.

At the beginning of the src/app.ts file, I add the swagger package import:

import swagger from 'feathers-swagger';

Then, before the “app.configure(services)”, I add the Swagger declaration:

app.configure(swagger({
  specs: {
    info: {
      title: 'Workshop API ',
      description: 'Workshop API rest services',
      version: '1.0.0',
    }
  },
  ui: swagger.swaggerUI({ docsPath: '/docs' }),
}))

Note: the position of the declaration in the file is very important: if it’s after the services configuration, the Swagger interface will be empty.

Second step: expose the service in Swagger UI

Once the feathers-swagger package has been installed and initialized in the project, all I have to do is tell the services what to expose. To do this, I add a docs part to my service workshop service in the file (src/services/workshop/workshop.ts).


// A configure function that registers the service and its hooks via `app.configure`
export const workshop = (app: Application) => {
  // Register our service on the Feathers application
  app.use(workshopPath, new WorkshopService(getOptions(app)), {
    // A list of all methods this service exposes externally
    methods: workshopMethods,
    // You can add additional custom events to be sent to clients here
    events: [],
    docs: createSwaggerServiceOptions({
      schemas: { workshopSchema, workshopDataSchema, workshopPatchSchema, workshopQuerySchema },
      docs: {
          // any options for service.docs can be added here
          description: 'Workshop service',
      }
    }),
  })

Don’t forget to add the necessary imports at the beginning of the file:

import {
  workshopDataValidator,
  workshopPatchValidator,
  workshopQueryValidator,
  workshopResolver,
  workshopExternalResolver,
  workshopDataResolver,
  workshopPatchResolver,
  workshopQueryResolver,
  workshopDataSchema,
  workshopPatchSchema,
  workshopQuerySchema,
  workshopSchema
} from './workshop.schema'

import type { Application } from '../../declarations'
import { WorkshopService, getOptions } from './workshop.class'
import { workshopPath, workshopMethods } from './workshop.shared'
import { createSwaggerServiceOptions } from 'feathers-swagger'

Important : in the case of a TypeScript project, the docs property is not recognized. An additional type declaration must therefore be added. In the src/declarations.ts file, add :

declare module '@feathersjs/feathers' {
  interface ServiceOptions {
    docs?: ServiceSwaggerOptions;
  }
}

Testing the UI

As usual, to test the service, I use the command :

npm run dev

Once the server has been started, simply access the docs page: http://localhost:3030/docs/

Swagger UI methods list

From the Swagger interface, I can test API methods:

Swagger UI method test

Conclusion

Adding a UI to explore the Feathers.js API is quick and easy, thanks to our ecosystem packages.

Swagger UI is a very useful tool, and adding it to your project is a good idea in many cases, such as :

  • When developing the API itself, to test methods and make sure they work properly
  • For the front-end developer using the API, it’s easy to know which methods are available and how to use them.
  • In the case of a public API, users can easily support and test methods using the UI