based on https://github.com/dgraph-io/badger/blob/f50343ff404d8198df6dc83755ec2eab863d5ff2/db_test.go#L1939

subscriptions.go

package main

import (
	"context"
	"fmt"
	"log"
	"sync"

	badger "github.com/dgraph-io/badger/v2"
	"github.com/dgraph-io/badger/v2/pb"
	"github.com/dgraph-io/dgo/v2/protos/api"
)

func main() {
	// open local database
	db, err := badger.Open(badger.DefaultOptions("/tmp/dgraph/p"))
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	handleSubscription := func(kvl *pb.KVList) error {
		log.Println("subscription handled")
		for _, kv := range kvl.GetKv() {
			fmt.Println(string(kv.GetKey()), string(kv.GetValue()))
		}
		return nil
	}

	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()
		if err := db.Subscribe(ctx, handleSubscription, []byte("status")); err != nil {
			fmt.Println(err)
		}
	}()

	mu := &api.Mutation{
		SetNquads: []byte(` _:foo <status> "pending" .`),
	}
	req := &api.Request{CommitNow: true, Mutations: []*api.Mutation{mu}}
	res, err := txn.Do(ctx, req)

	if err != nil {
		log.Fatal(err)
	}
	
	cancel()
	wg.Wait()
}