[Chore] Brittle asynchronous processing of keywords

[olivierobert]

Issue

Upon uploading keywords, the scraping will be performed asynchronously via an event listener

google-searcher/src/search/listeners/search.listener.ts

Lines 17 to 27 in 36a95d4

	@OnEvent('file.uploaded', { async: true })
	async handleOrderCreatedEvent(payload: FileUploadedEvent) {
	for (const { keyword } of payload.rowObject) {
	const result = await this.searcher.search(keyword);
	await this.entityManager.save(SearchStat, {
	...result,
	keyword,
	});
	console.log('saved to db');
	}
	}

All keywords are processed in a loop. If any error occurs in the loop, the latter will stop, and all remaining keywords will not be scraped and will not even have been saved to the database. A queue (supported by Nest.JS, see: https://docs.nestjs.com/techniques/queues) would be a better fit in this case.

Warning

Using the observer pattern can be beneficial when there is more than one subscriber/consumer. Since the event is consumed in the same module as it is emitted, it creates indirection unnecessarily.

Expected

• Keywords should be stored in the database with a flag to track the scraping status as soon as they are uploaded
• A distinct background job to scrap the Google page for each keyword is then scheduled.

The benefits are:

• Fast CSV upload request
• The scraping of each keyword is isolated, i.e., one could error while others could be successful.