Golang中循环内如何扫描SQL行数据

Golang中循环内如何扫描SQL行数据 大家好 :wave:， 我是Go编程语言的新手，这是我在这个论坛的第一篇帖子，是一个在线课程推荐给我的。2022年还很新鲜，祝大家新年快乐。

我很难理解为什么不能在循环内返回一个sql行？或者我没有理解正确的做法？

我试图在PostgreSQL表中创建一个列，然后返回整个列的行并打印出来。我尝试在循环内完成这个操作（但行不通），而每当我在循环外做这件事时，它就能正常工作。请用你们的智慧启发我 :pray:。

数据库：

go-mvc=# select * from messages;
 id  | name  |     message     |         created_at
-----+-------+-----------------+----------------------------
 101 | Ori   | Skol!           | 2022-01-23 19:43:14.761144
 102 | Oin   | Raise the axes! | 2022-01-23 19:43:14.763818
 103 | Gloin | Bouncing around | 2022-01-23 19:43:14.764389
(3 rows)

控制器：

func CreateMessageProcessJSON(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		w.WriteHeader(405)
		return
	}
	if r.Header.Get("content-type") != "application/json" {
		w.WriteHeader(406)
		return
	}

	msgs := []models.MessageJSON{}
	helpers.ParseBody(r, &msgs)

	// 不工作
	// for _, msg := range msgs {
	// 	if err := msg.CreateFromJSON(); err != nil {
	// 		http.Error(w, http.StatusText(500), http.StatusInternalServerError)
	// 		return
	// 	}
	// }

	// 工作
	if err := msgs[0].CreateFromJSON(); err != nil {
		http.Error(w, http.StatusText(500), http.StatusInternalServerError)
		return
	}

	pd := models.PageDataJSON{
		msgs,
		models.RawData{Title: "Show json message"},
	}

	fmt.Fprintln(w, pd)
}

模型：

type MessageJSON struct {
	Id        int64     `json:"id"`
	Name      string    `json:"name"`
	Message   string    `json:"msg"`
	CreatedAt time.Time `json:"created_at"`
}

func (msg *MessageJSON) CreateFromJSON() (err error) {
	// 验证表单值
	if msg.Name == "" || msg.Message == "" {
		errors.New("this error just triggers another error")
		return
	}

	statement := `INSERT INTO messages (name, message, created_at) VALUES ($1, $2, $3) RETURNING id, name, message, created_at`

	stmt, err := db.Db.Prepare(statement)
	if err != nil {
		return
	}

	// 使用 QueryRow 返回一行并将返回的 id 扫描到 User 结构体中
	err = stmt.QueryRow(msg.Name, msg.Message, time.Now()).Scan(&msg.Id, &msg.Name, &msg.Message, &msg.CreatedAt)
	return
}

每次我发出POST请求时，列都会被创建，但 scan 似乎对我的结构体没有任何影响。

带循环的POST请求：

% curl -X POST \
http://localhost:8080/messages/createjson/process \
-H "Content-Type: application/json" \
-d '[{"name":"Ori", "msg":"Skol!"},{"name":"Oin","msg":"Raise the axes!"},{"name":"Gloin","msg":"Bouncing around"}]' -v

Note: Unnecessary use of -X or --request, POST is already inferred.
*   Trying ::1:8080...
* connect to ::1 port 8080 failed: Connection refused
*   Trying 127.0.0.1:8080...
* Connected to localhost (127.0.0.1) port 8080 (#0)
> POST /messages/createjson/process HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.77.0
> Accept: */*
> Content-Type: application/json
> Content-Length: 111
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Date: Sun, 23 Jan 2022 18:43:14 GMT
< Content-Length: 178
< Content-Type: text/plain; charset=utf-8
<
{[{0 Ori Skol! 0001-01-01 00:00:00 +0000 UTC} {0 Oin Raise the axes! 0001-01-01 00:00:00 +0000 UTC} {0 Gloin Bouncing around 0001-01-01 00:00:00 +0000 UTC}] {Show json message}}
* Connection #0 to host localhost left intact

不带循环的POST请求（会给我正确的ID，但这不是我想要的）：

% curl -X POST \
http://localhost:8080/messages/createjson/process \
-H "Content-Type: application/json" \
-d '[{"name":"ID?", "msg":"CHEERS!!!"}]' -v
Note: Unnecessary use of -X or --request, POST is already inferred.
*   Trying ::1:8080...
* connect to ::1 port 8080 failed: Connection refused
*   Trying 127.0.0.1:8080...
* Connected to localhost (127.0.0.1) port 8080 (#0)
> POST /messages/createjson/process HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.77.0
> Accept: */*
> Content-Type: application/json
> Content-Length: 35
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Date: Sun, 23 Jan 2022 18:52:18 GMT
< Content-Length: 83
< Content-Type: text/plain; charset=utf-8
<
{[{105 ID? CHEERS!!! 2022-01-23 19:52:18.941026 +0000 +0000}] {Show json message}}
* Connection #0 to host localhost left intact

保重。