Koa Decorative

KOA Decorative is a library built to simplify routing. This library is designed to route traffic through the use of class based decorators instead of a routing configuration file.

Installation

Install Koa Decorative and the underlying router that Koa Decorative works with using npm:

npm install --save koa-decorative koa-tree-router

This package requires that you enable experimental decorators in your tsconfig.json file for your project:

{
  "compilerOptions": {
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true
  }
}

Usage

index.ts

This is what a basic CRUD controller will look like:

import { Context } from 'koa';
import { Controller, Pre, Get, Post, Put, Patch, Delete } from 'koa-decorative';

// A simple request specific middleware handled before the list action
const preListAction = async (ctx: Context, next: () => Promise<any>) => {
  console.log('before the list action');
  await next();
  console.log('after the list action');
}

@Controller('/simple')
class SimpleController {
  constructor(private simpleService) { }

  @Get()
  @Pre(preListAction)
  list(ctx: Context) {
    const result = this.simpleService.list();

    ctx.body = { data: result };
  }

  @Post()
  create(ctx: Context) {
    const result = this.simpleService.create();

    ctx.body = { data: result };
  }

  @Get('/:id')
  detail(ctx: Context) {
    const result = this.simpleService.detail();

    ctx.body = { data: result };
  }

  @Put('/:id')
  @Patch('/:id')
  update() {
    const result = this.simpleService.update();

    ctx.body = { data: result };
  }

  @Delete('/:id')
  delete() {
    const result = this.simpleService.delete();

    ctx.body = { data: result };
  }
}

export default SimpleController;

Note: All class instances are singletons and not request specific. Take care not to store any request specific information in the class itself. However it is a great place to inject depencencies for the controller.

Create an index.ts in the controllers directory and initialize your controllers:

import { SimpleService } from '../services';

import SimpleController from './SimpleController';

const simpleService = new SimpleService();

new SimpleController(simpleService);

Then just build the routes in your apps main index.ts or app.ts file:

import { buildRoutes } from 'koa-decorative';

import './controllers';

const app = new Koa();

app.use(buildRoutes());

app.listen(3000);

The routes defined in the controllers will be automatically registered with the route manager. And you just need to pass the built routes to app.use to automatically build the routing for all of the initialized controllers.