koa2-module

Abstract class for Koa2 module building with async/await support.

Requirements

• Koa 2.x
• Node 7.x with --harmony flag

Installation

npm install koa2-module --save

Basic example

const Koa = require( 'koa' );
const Module = require( 'koa2-module' );

class FantasticModule extends Module {
   moduleLoad( options ) {
      this.body = 'Hello ' + options.body;
      return this.fantasticMiddlware();
   }
   fantasticMiddlware() {
      return async (ctx) => {
         ctx.body = this.body;
      };
   }
}

const app = new Koa();

new FantasticModule( app, { body: 'Fantastic!' } );

app.listen( 3000 );

Usage

constructor(app, options)

constructor takes two arguments, Koa2 application instance and options object. Should not be overridden.

Options

There are only two build in options, enabled and disabled, which can be used to disable the whole module.

| Option | Default value | --- | --- | enabled | true | disabled | false

Example

new FantasticModule( app, {
   enabled: process.env.NODE_ENV === 'production';
} );

moduleLoad(options)

moduleLoad(options) is main lifecycle method executed during application initialization. It takes options object passed from the constructor and should return a method that returns Koa2 middleware function. It can be a common function or async function.

Common function example

moduleLoad( options ) {
   this.something = doSomething( options );
   return this.middleware();
}

Async function example

async moduleLoad( options ) {
   this.something = await doSomething( options );
   return this.middleware();
}

Middleware

Module can have any number of methods returning middleware functions. In moduleLoad() method you can control which middleware will be used.

Example

class FantasticModule extends Module {
   async moduleLoad( options ) {
      var result = await doSomething( options );

      if( process.env.NODE_ENV === 'production' ) {
         return this.productionMiddleware();
      }
      else if( process.env.NODE_ENV === 'development' ) {
         return this.developmentMiddleware();
      }
      else {
         return this.otherMiddleware();
      }
   }
   productionMiddleware() {
      return async (ctx) => {
         ctx.body = 'Production!';
      };
   }
   developmentMiddleware() {
      return async (ctx) => {
         ctx.body = 'Development!';
      };
   }
   otherMiddleware() {
      return async (ctx) => {
         ctx.body = 'Other?';
      };
   }
}