Use Redis GeoHash with Spring boot

One very handy Data Structure when it comes to Redis is the GeoHash Data structure. Essentially it is a sorted set that generates a score based on the longitude and latitude.

We will spin up a Redis database using Compose

services:
  redis:
    image: redis
    ports:
      - 6379:6379

Can be run like this

docker compose up

You can find more on Compose on the Developers Essential Guide to Docker Compose.

Let’s add our dependencies

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <groupId>org.example</groupId>
    <version>1.0-SNAPSHOT</version>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>location-service</artifactId>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.7.5</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.24</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
            <version>2.7.5</version>
        </dependency>
    </dependencies>
</project>

We shall start with our Configuration. For convenience on injecting we shall create a GeoOperations<String,String> bean.

package org.location;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.core.GeoOperations;
import org.springframework.data.redis.core.RedisTemplate;

@Configuration
public class RedisConfiguration {

    @Bean
    public GeoOperations<String,String> geoOperations(RedisTemplate<String,String> template) {
        return template.opsForGeo();
    }

}

Our model would be this one

package org.location;

import lombok.Data;

@Data
public class Location {

    private String name;
    private Double lat;
    private Double lng;

}

This simple service will persist venue locations and also fetch venues nearby of a location.

package org.location;

import java.util.List;
import java.util.stream.Collectors;

import org.springframework.data.geo.Circle;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.geo.Metrics;
import org.springframework.data.geo.Point;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.GeoOperations;
import org.springframework.data.redis.domain.geo.GeoLocation;
import org.springframework.stereotype.Service;

@Service
public class GeoService {

    public static final String VENUS_VISITED = "venues_visited";
    private final GeoOperations<String, String> geoOperations;

    public GeoService(GeoOperations<String, String> geoOperations) {
        this.geoOperations = geoOperations;
    }

    public void add(Location location) {
        Point point = new Point(location.getLng(), location.getLat());
        geoOperations.add(VENUS_VISITED, point, location.getName());

    }

    public List<String> nearByVenues(Double lng, Double lat, Double kmDistance) {
        Circle circle = new Circle(new Point(lng, lat), new Distance(kmDistance, Metrics.KILOMETERS));
        GeoResults<RedisGeoCommands.GeoLocation<String>> res = geoOperations.radius(VENUS_VISITED, circle);
        return res.getContent().stream()
                  .map(GeoResult::getContent)
                  .map(GeoLocation::getName)
                  .collect(Collectors.toList());
    }

}

We shall also add a controller

package org.location;

import java.util.List;

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class LocationController {

    private final GeoService geoService;

    public LocationController(GeoService geoService) {
        this.geoService = geoService;
    }

    @PostMapping("/location")
    public ResponseEntity<String> addLocation(@RequestBody Location location) {
        geoService.add(location);
        return ResponseEntity.ok("Success");
    }

    @GetMapping("/location/nearby")
    public ResponseEntity<List<String>> locations(Double lng, Double lat, Double km) {
        List<String> locations = geoService.nearByVenues(lng, lat, km);
        return ResponseEntity.ok(locations);
    }

}

Then let’s add an element.

curl --location --request POST 'localhost:8080/location' \
--header 'Content-Type: application/json' \
--data-raw '{
	"lng": 51.5187516,
	"lat":-0.0814374,
	"name": "liverpool-street"
}'

Let’s retrieve the element of the api

curl --location --request GET 'localhost:8080/location/nearby?lng=51.4595573&lat=0.24949&km=100'
> [
    "liverpool-street"
]

And also let’s check redis

ZRANGE venues_visited 0 -1 WITHSCORES
1) "liverpool-street"
2) "2770072452773375"

We did it, pretty convenient for our day to day distance use cases.