By Redis Team

We're getting toward the end of the tutorial here, but before we go, I'd like to add that location tracking piece that I mentioned way back in the beginning. This next bit of code should be easily understood if you've gotten this far as it's not really doing anything I haven't talked about already.

Add a new file called location-router.js in the routers folder:

import { Router } from 'express'
import { personRepository } from '../om/person.js'

export const router = Router()

router.patch('/:id/location/:lng,:lat', async (req, res) => {

  const id = req.params.id
  const longitude = Number(req.params.lng)
  const latitude = Number(req.params.lat)

  const locationUpdated = new Date()

  const person = await personRepository.fetch(id)
  person.location = { longitude, latitude }
  person.locationUpdated = locationUpdated
  await personRepository.save(person)

  res.send({ id, locationUpdated, location: { longitude, latitude } })
})

Here we're calling .fetch() to fetch a person, we're updating some values for that person—the .location property with our longitude and latitude and the .locationUpdated property with the current date and time. Easy stuff.

To use this Router, import it in server.js:

/* import routers */
import { router as personRouter } from './routers/person-router.js'
import { router as searchRouter } from './routers/search-router.js'
import { router as locationRouter } from './routers/location-router.js'

And bind the router to a path:

/* bring in some routers */
app.use('/person', personRouter, locationRouter)
app.use('/persons', searchRouter)

And that's that. But this just isn't enough to satisfy. It doesn't show you anything new, except maybe the usage of a date field. And, it's not really location tracking. It just shows where these people last were, no history. So let's add some!.

To add some history, we're going to use a Redis Stream. Streams are a big topic but don't worry if you’re not familiar with them, you can think of them as being sort of like a log file stored in a Redis key where each entry represents an event. In our case, the event would be the person moving about or checking in or whatever.

But there's a problem. Redis OM doesn’t support Streams even though Redis Stack does. So how do we take advantage of them in our application? By using Node Redis. Node Redis is a low-level Redis client for Node.js that gives you access to all the Redis commands and data types. Internally, Redis OM is creating and using a Node Redis connection. You can use that connection too. Or rather, Redis OM can be told to use the connection you are using. Let me show you how.