Serialize data to/from Redis in a custom type

babies.go

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"github.com/go-redis/redis/v8"
	"os"
	"time"
)

// Baby is a simple demo data struct
type Baby struct {
	Name        string
	DateOfBirth time.Time
}

// MarshalBinary is needed to encode the data before storing in Redis,
// and to retrieve it later.
//
// **NOTE** the receiver must be a concrete type (NOT a pointer) of the
// serialization to Redis will fail.
func (i Baby) MarshalBinary() ([]byte, error) {
	// Obviously it makes no sense to serialize to JSON to store in Redis,
	// but the same approach would work with, for example, Protobuf messages
	// with an efficent binary encoding.
	return json.Marshal(i)
}

// UnmarshalBinary is the dual of MarshalBinary and will parse the
// binary data into the receiver.
// See: https://pkg.go.dev/encoding
func (i *Baby) UnmarshalBinary(data []byte) error {
	return json.Unmarshal(data, i)
}

func main() {

	// To run Redis as a container, see: https://hub.docker.com/_/redis/
	//
	// To connect from the client, see:
	// https://redis.uptrace.dev/guide/server.html#connecting-to-redis-server
	rdb := redis.NewClient(&redis.Options{
		Addr:     "localhost:6379",
		Password: "", // no password set
		DB:       0,  // use default DB
	})

	// Creates a Context which will time out after 200ms
	// See: https://go.dev/blog/context
	timeout, _ := time.ParseDuration("200ms")
	ctx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()

	// Congratulations to mum & dad!
	baby := Baby{
		Name:        "Charlie",
		DateOfBirth: time.Now(),
	}

	start := time.Now()
	cmd := rdb.Set(ctx, "charlie", baby, timeout)
	val, err := cmd.Result()
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	// This will just emit `OK`
	fmt.Println(val)

	getCmd := rdb.Get(ctx, "charlie")
	data, err := getCmd.Bytes()
	if err == redis.Nil {
		fmt.Println("No babies found!")
	} else if err != nil {
		fmt.Println(err)
		os.Exit(1)
	} else {
		var baby Baby
		err = baby.UnmarshalBinary(data)
		if err != nil {
			fmt.Println(err)
			os.Exit(1)
		}
		fmt.Println(baby)
	}

	fmt.Printf("Took %q\n", time.Since(start))
}