package main

import (
	"github.com/mongodb/mongo-go-driver/bson"
	"log"
)

type TestStruct struct {
	TestValue *string `bson:"test_value,omitempty"`
}

func main() {
	testString := "test value goes here"
	t := TestStruct{
		TestValue: &testString,
	}
	data, err := bson.Marshal(t)
	if err != nil {
		log.Fatalf("Failed to marshal. Error: %v", err)
	}
	unt := TestStruct{}
	err = bson.Unmarshal(data, &unt)
	if err != nil {
		log.Fatalf("Failed to unmarshal. Error: %v", err)
	}
	log.Printf("Result: %+v")
	if unt.TestValue == nil {
		return
	}
	log.Printf("Contained string: %+v", *unt.TestValue)
}

reflect.Value.Addr of unaddressable value