mysql - Golang 映射多结果

Question

var newR[] struct {
        id string
        eventid string
        excel_id string
        userid string
        hallid string
}

i := 0
for rows.Next() {
    var id, eventid, excel_id, userid, hallid string
    err = rows.Scan(&id, &eventid, &excel_id, &userid, &hallid)

    // Here is what I want to do
    newR[i].id = id
    newR[i].eventid = eventid
    newR[i].excel_id = excel_id
    newR[i].userid = userid
    newR[i].hallid = hallid
    i++
}

最终我收到一条错误消息“运行时错误:索引超出范围”在/myapp/app/controllers/app.go(大约第 122 行)

newR[i].id = id

任何建议或提示都会有所帮助。谢谢。

Answer 1

您不需要为每个字段创建局部变量，只需创建一个结构并使用它来读取数据并使用 slice 来累积结果:

// struct definition must be out of functions body
type newR struct {
    id string
    eventid string
    excel_id string
    userid string
    hallid string
}

var newRs []newR
for rows.Next() {
    var current newR
    err = rows.Scan(&current.id, &current.eventid, &current.excel_id, &current.userid, &current.hallid)
    newRs = append(newRs, r)
}

而且最好在 rows.Next() 和 rows.Scan(...) 之后检查错误。