example of listening firestore realtime update

firestore-listen-doc.go

package main

import (
	"firebase.google.com/go"
	"cloud.google.com/go/firestore"
	"context"
	"log"
	"math/rand"
	"fmt"
)

var client *firestore.Client
var ctx = context.Background()

func main(){
	conf := &firebase.Config{ProjectID: "GCP_PROJECT_ID"}
	app, err := firebase.NewApp(ctx, conf)
	if err != nil {
		log.Fatalln(err)
	}

	client, err = app.Firestore(ctx)
	if err != nil {
		log.Fatalln(err)
	}
	defer client.Close()

	snapshotIterator := client.Collection("users").Doc("user1").Snapshots(ctx)
	defer snapshotIterator.Stop()

	for{
		data, err := snapshotIterator.Next()
		if err != nil {
			log.Fatalln(err)
		}
		fmt.Printf("data exist: %+v, data: %+v\n", data.Exists(), data.Data())
	}
}