api.js

/**
 *  RxJS in action
 *  Chapter #
 *  @author Paul Daniels
 *  @author Luis Atencio
 */
'use strict';
const connectRoute = require('connect-route');

/*
*
* Add all backend apis here
*
* */
const fs = require('fs');
const Rx = require('rxjs');

const observableRead = Rx.Observable.bindNodeCallback(fs.readFile);

module.exports = connectRoute(function(router) {

  const defaultHtml = observableRead(__dirname + '/examples/default/default.html', 'utf8');

  /**
   * Example of how to set up a new route
   */
  router.post('/echo', function(req, res) {
    res.end(JSON.stringify(req.body));
  });

  const dataItems = [
    {id: 'A', img: 'abc'},
    {id: 'B', img: 'def'}
    ];

  /**
   * For sample 7.2
   */
  router.get('/data', function(req, res, next) {
    res.setHeader('Content-Type', 'application/json');
    Rx.Observable.from(dataItems)
      .map(({id}) => ({id}))
      .toArray()
      .map(x => JSON.stringify(x))
      .subscribe(body => res.end(body));
  });


  router.get('/data/:item/info', function(req, res, next) {
    res.setHeader('Content-Type', 'application/json');
    const {item} = req.params;

    Rx.Observable.from(dataItems)
      .find(({id}) => item === id)
      .map(x => JSON.stringify(x))
      .subscribe(body => res.end(body));
  });

  router.get('/data/images/:image', function(req, res, next) {
    // Throw 500s so that we can see the error
    res.statusCode = 500;
    res.end('');
  });

  /**
   * Retrieves a specific listing by chapter and number
   */
  router.get('/example/:chapter/:id', function(req, res, next) {
    const chapter = req.params.chapter;
    const id = req.params.id;
    const basePath = buildFilePath(chapter, id);

    const jsPath = basePath('.js');
    const cssPath = basePath('.css');
    const htmlPath = basePath('.html');

    const defaultErrorHandler = (defaultValue = Rx.Observable.of('')) =>
      source => source.catch(err => defaultValue);

    Rx.Observable.forkJoin(
      observableRead(jsPath, 'utf8').let(defaultErrorHandler()),
      observableRead(cssPath, 'utf8').let(defaultErrorHandler()),
      observableRead(htmlPath, 'utf8').let(defaultErrorHandler(defaultHtml)),
      (js, css, html) => ({js, css, html})
    )
      .subscribe(contents => {
        res.end(JSON.stringify(contents));
      }, err => console.error(err));
  })

});

function buildFilePath(chapter, id) {
  return (ext) => `${__dirname}/examples/${chapter}/${id}/${chapter}_${id}${ext}`;
}