main.go

package main

import (
	"encoding/csv"
	"github.com/maxmind/mmdbwriter"
	"github.com/maxmind/mmdbwriter/inserter"
	"github.com/maxmind/mmdbwriter/mmdbtype"
	"io"
	"log"
	"net"
	"os"
	"strconv"
)

func main() {
	csvfile, err := os.Open("input.csv")
	csvreader := csv.NewReader(csvfile)
	if err != nil {
		log.Fatalln("Couldn't open the csv file", err)
	}
	// Load the database we wish to enrich.
	writer, err := mmdbwriter.Load("GeoLite2-City.mmdb", mmdbwriter.Options{ IncludeReservedNetworks: true, Languages: []string{"en"}})
	if err != nil {
		log.Fatal(err)
	}

	for {
		// Read each record from csv
		record, err := csvreader.Read()
		if err == io.EOF {
			break
		}
		if err != nil {
			log.Fatal(err)
		}
		_, sreNet, err := net.ParseCIDR(record[0])
		if err != nil {
			log.Fatal(err)
		}
		euBool, err := strconv.ParseBool(record[3])
		lat, err := strconv.ParseFloat(record[6], 32)
		long, err := strconv.ParseFloat(record[7], 32)
		accuracy, err := strconv.ParseInt(record[8], 0, 32)
		sreData := mmdbtype.Map{
			`continent`: mmdbtype.Map{
				`code`: mmdbtype.String(record[1]),
			},
			`country`: mmdbtype.Map{
				`iso_code`:             mmdbtype.String(record[2]),
				`is_in_european_union`: mmdbtype.Bool(euBool),
			},
			`subdivisions`: mmdbtype.Slice{
				mmdbtype.Map{
					`iso_code`: mmdbtype.String(record[4]),
				},
			},
			`city`: mmdbtype.Map{
				`names`: mmdbtype.Map{
					`en`: mmdbtype.String(record[5]),
				},
			},
			`location`: mmdbtype.Map{
				`latitude`:        mmdbtype.Float32(lat),
				`longitude`:       mmdbtype.Float32(long),
				`accuracy_radius`: mmdbtype.Int32(accuracy),
				`time_zone`:       mmdbtype.String(record[9]),
			},
			`postal`: mmdbtype.Map{
				`code`: mmdbtype.String(record[10]),
			},
		}
		if err := writer.InsertFunc(sreNet, inserter.TopLevelMergeWith(sreData)); err != nil {
			log.Fatal(err)
		}
	}

	// Write the newly enriched DB to the filesystem.
	fh, err := os.Create("GeoLite2-City-with-Local.mmdb")
	if err != nil {
		log.Fatal(err)
	}
	_, err = writer.WriteTo(fh)
	if err != nil {
		log.Fatal(err)
	}
}