Usage

For the basic setup you need to create a Provider (strategy) the PopApiScraper instance can use. The PopApiScraper implements the strategy pattern, where the providers are the strategies.

The example below makes a HTTP GET request to a web service or website. from there on you are free to implement how and what data you want to get from it.

// ./ExampleProvider.js
import { AbstractProvider, HttpService } from 'pop-api-scraper'

// Extend from the internal AbstractProvider.
export default class ExampleProvider extends AbstractProvider {

  constructor(PopApiScraper, {name, configs, maxWebRequests = 2}) {
    super(PopApiScraper, {name, configs, maxWebRequests})
  }

  // Override the `scrapeConfig` method to get the content from one
  // configuration.
  scrapeConfig(config) {
    // A HTTP service to send HTTP requests.
    this.httpService = new HttpService({
      baseUrl: config.baseUrl
    })

    // HTTP  GET request to: https://jsonplaceholder.typicode.com/posts?foo=bar
    return this.httpService.get('/posts', config.httpOptions)
      .then(res => res.data)
  }

}

Bundle it all up together with pop-api:

// ./index.js
import os from 'os'
import { PopApi } from 'pop-api'
import { join } from 'path'
import { Cron, PopApiScraper } from 'pop-api-scraper'

import ExampleProvider from './ExampleProvider'

(async () => {
  try {
    // Let the PopApiScraper use the ExampleProvider o scrape data.
    PopApiScraper.use(ExampleProvider, {
      name: 'example-provider',
      configs: [{
        baseUrl: 'https://jsonplaceholder.typicode.com',
        httpOptions: {
          query: {
            foo: 'bar'
          }
        }
      }],
      maxWebRequests: 2
    })

    // Register the PopApiScraper middleware to the pop-api instance.
    PopApi.use(PopApiScraper, {
      statusPath: join(...[os.tmpdir(), 'status.json']),
      updatedPath: join(...[os.tmpdir(), 'updated.json'])
    })
    // Optionally you can use the Cron middleware to scrape for content on a
    // regulat basis.
    PopApi.use(Cron, {
      cronTime: '0 0 */6 * * *',
      start: false
    })

    // PopApi now has a `scraper` instance.
    const res = await PopApi.scraper.scrape()
    console.info(res[0])
  } catch (err) {
    console.error(err)
  }
})()