Redis Search - Rental Availability

Summary

This post covers a very specific use case of Redis in the short-term rental domain.  Specifically, Redis is used to find property availability in a given geographic area and date/time slot.

Architecture

Code Snippets

Data Load

The code below loads rental properties as Redis JSON objects and US Postal ZIP codes with their associated lat/longs as Redis strings.

	async #insertProperties() {
	const csvStream = fs.createReadStream("./data/co.csv").pipe(parse({ delimiter: ",", from_line: 2}));
	let id = 1;
	for await (const row of csvStream) {
	const doc = {
	"id": id,
	"address": {
	"coords": `${row[0]} ${row[1]}`,
	"number": row[2],
	"street": row[3],
	"unit": row[4],
	"city": row[5],
	"state": "CO",
	"postcode": row[8]
	},
	"owner": {
	"fname": uniqueNamesGenerator({dictionaries: [names], style: 'capital', length: 1, separator: ' '}),
	"lname": uniqueNamesGenerator({dictionaries: [names], style: 'capital', length: 1, separator: ' '}),
	},
	"type": `${TYPES[Math.floor(Math.random() * TYPES.length)]}`,
	"availability": this.#getAvailability(),
	"rate": Math.round((Math.random() * 250 + 125) * 100) / 100
	}
	await this.client.json.set(`property:${id}`, '.', doc);
	id++;
	if (id > MAX_PROPERTIES) {
	break;
	}
	}
	async #insertZips() {
	const csvStream = fs.createReadStream("./data/zip_lat_long.csv").pipe(parse({ delimiter: ",", from_line: 2}));
	for await (const row of csvStream) {
	const zip = row[0];
	const lat = row[1];
	const lon = row[2];
	await this.client.set(`zip:${zip}`, `${lon} ${lat}`);
	}
	}

view raw rental-load.js hosted with ❤ by GitHub

Property Search

The code below represents an Expressjs route for performing searches on the Redis properties.  The search is performed on rental property type and geographic distance from a given location.

	app.post('/property/search', async (req, res) => {
	const { type, zip, radius, begin, end } = req.body;
	console.log(`app - POST /property/search ${JSON.stringify(req.body)}`);
	try {
	const loc = await client.get(`zip:${zip}`);
	if (!loc) {
	throw new Error('Zip code not found');
	}
	const query = `@type:{${type}} @coords:[${loc} ${radius} mi]`;
	const docs = await client.ft.aggregate('propIdx', query,
	{
	DIALECT: 3,
	LOAD: [
	'@__key',
	{ identifier: `$.availability[?(@.begin<=${begin} && @.end>=${end})]`,
	AS: 'match'
	}
	],
	STEPS: [
	{ type: AggregateSteps.FILTER,
	expression: 'exists(@match)'
	},
	{
	type: AggregateSteps.SORTBY,
	BY: {
	BY: '@rate',
	DIRECTION: 'ASC'
	}
	},
	{
	type: AggregateSteps.LIMIT,
	from: 0,
	size: 3
	}
	]
	});
	if (docs && docs.results) {
	let properties = [];
	for (const result of docs.results) {
	const rental_date = JSON.parse(result.match);
	const property = {
	"key": result.__key,
	"rate": result.rate,
	"begin": rental_date[0].begin,
	"end": rental_date[0].end
	};
	properties.push(property);
	}
	console.log(`app - POST /property/search - properties found: ${properties.length}`);
	res.status(200).json(properties);
	}
	else {
	console.log('app - POST /property/search - no properties found');
	res.status(401).send('No properties found');
	}
	}
	catch (err) {
	console.log(`app - POST /property/search - error: ${err.message}`);
	res.status(400).json({ 'error': err.message });
	}
	});

view raw rental-search.js hosted with ❤ by GitHub

Source

https://github.com/Redislabs-Solution-Architects/rental-availability

Copyright ©1993-2024 Joey E Whelan, All rights reserved.