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[pkg] go-redis 筆記

資料來源

基本使用​

建立 client​

/**
 * Source
 * https://betterstack.com/community/guides/scaling-go/redis-caching-golang/
 * https://ithelp.ithome.com.tw/articles/10249929
 **/
func NewClient(ctx context.Context) *redis.Client {
	rdb := redis.NewClient(&redis.Options{
		Addr:     "localhost:6379",
		Password: "",
		DB:       0,
	})

	// Perform basic diagnostic to check if the connection is working
	pong, err := rdb.Ping(ctx).Result()
	if err != nil {
		log.Fatalln("Redis connection was refused")
	}

	fmt.Println(pong)
	return rdb
}

func main() {
	ctx := context.Background()
	rdb := NewClient(ctx)

	// Ensure that the connection is properly close gracefully
	defer rdb.Close()
}

Set：使用 client 設值與更新值​

Update

在 Redis 中，更新資料也是用 SET。

/**
 * Source
 * https://betterstack.com/community/guides/scaling-go/redis-caching-golang/
 * https://ithelp.ithome.com.tw/articles/10249929
 **/
func main() {
  ctx := context.Background()
	rdb := NewClient(ctx)
	defer rdb.Close()

  // 設成 0 表示不會過期
	err := rdb.Set(ctx, "FOO", "BAR", 0).Err()
  // // highlight-end
	if err != nil {
		fmt.Println("Failed to add FOO <> BAR key-value pair")
		return
	}

	rdb.Set(ctx, "INT", 5, 0)
	rdb.Set(ctx, "FLOAT", 5.5, 0)
	rdb.Set(ctx, "EXPIRING", 15, 30*time.Minute)
  
	// set struct data
	type Person struct {
		Name string `redis:"name"`
		Age  int    `redis:"age"`
	}
	rdb.HSet(ctx, "STRUCT", Person{"John Doe", 15})
}

Get：使用 client 取值​

/**
 * Source
 * https://betterstack.com/community/guides/scaling-go/redis-caching-golang/
 * https://ithelp.ithome.com.tw/articles/10249929
 **/
func main() {
	ctx := context.Background()
	rdb := NewClient(ctx)
	defer rdb.Close()  

	// 取值
 	result, err := rdb.Get(ctx, "FOO").Result()
	if err != nil {
		log.Println("client.Get failed", err)
	}

	// 取值並判斷值是否存在（字串）
	result, err = rdb.Get(ctx, "BAR").Result()
	if err == redis.Nil {
		fmt.Println("Key BAR not found in Redis cache")
	} else if err != nil {
		fmt.Println("client.Get failed", err)
	} else {
		fmt.Printf("BAR has value %s\n", result)
	}
  
	// 讀取 Int 
	intValue, err := rdb.Get(ctx, "INT").Int()
	if err != nil {
		fmt.Println("Key INT not found in Redis cache")
	} else {
		fmt.Printf("INT has value %d\n", intValue)
	}  
  
	// 讀取 struct data
	var person Person
	err = rdb.HGetAll(ctx, "STRUCT").Scan(&person)
	if err != nil {
		fmt.Println("Key STRUCT not found in Redis cache")
	} else {
		fmt.Printf("STRUCT has value %+v\n", person)
	}  
}

Del：刪除資料​

/**
 * Source
 * https://betterstack.com/community/guides/scaling-go/redis-caching-golang/
 **/
func main() {
  ctx := context.Background()
	rdb := NewClient(ctx)
	defer rdb.Close()

	rdb.Set(ctx, "FOO", "BAR", 0)
	result, err := rdb.Get(ctx, "FOO").Result()
	if err != nil {
		fmt.Println("FOO not found")
	} else {
		fmt.Printf("FOO has value %s\n", result)
	}

	// Deleting the key "FOO" and its associated value
	rdb.Del(ctx, "FOO")
	result, err = rdb.Get(ctx, "FOO").Result()
	if err != nil {
		fmt.Println("FOO not found")
	} else {
		fmt.Printf("FOO has value %s\n", result)
	}
}

參考​