英文:
Go lang map multi result
问题
以下是翻译好的内容：
var newR []struct {id stringeventid stringexcel_id stringuserid stringhallid string}i := 0for rows.Next() {var id, eventid, excel_id, userid, hallid stringerr = rows.Scan(&id, &eventid, &excel_id, &userid, &hallid)// 这里是我想要做的newR = append(newR, struct {id stringeventid stringexcel_id stringuserid stringhallid string}{})newR[i].id = idnewR[i].eventid = eventidnewR[i].excel_id = excel_idnewR[i].userid = useridnewR[i].hallid = hallidi++}最终我得到了一个错误消息 "runtime error: index out of range"在 /myapp/app/controllers/app.go（大约在第122行）newR[i].id = id有什么建议或提示将会有所帮助。谢谢。
英文:
var newR[] struct {id stringeventid stringexcel_id stringuserid stringhallid string}i := 0for rows.Next() {var id, eventid, excel_id, userid, hallid stringerr = rows.Scan(&id, &eventid, &excel_id, &userid, &hallid)// Here is what I want to donewR[i].id = idnewR[i].eventid = eventidnewR[i].excel_id = excel_idnewR[i].userid = useridnewR[i].hallid = hallidi++}
Eventually I got an error msg "runtime error: index out of range"
In /myapp/app/controllers/app.go (around line 122)
newR[i].id = id
Any suggestions or tips will helps. Thanks.
答案1
得分: 0
使用append函数来添加一个新元素并初始化一个尚未分配的切片。
newElement := struct {id stringeventid stringexcel_id stringuserid stringhallid string} {id: id,eventid: eventid,excel_id: excel_id,userid: userid,hallid: hallid,}newR = append(newR, newElement)...
抱歉我没有使用fmt或测试它，但我是从我的手机上输入的。
英文:
Use append to add a new element and initialize a not yet allocated slice.
newElement := struct {id stringeventid stringexcel_id stringuserid stringhallid string} {id: id,eventid: eventid,excel_id: excel_id,userid: userid,hallid: hallid,}newR = append(newR, newElement)
...
Sorry for not fmt or test it out but I typed this from my mobile.
答案2
得分: 0
你不需要为每个字段创建本地变量，只需创建一个结构体并使用它来读取数据，并使用切片来累积结果：
// 结构体定义必须在函数体外部type newR struct {id stringeventid stringexcel_id stringuserid stringhallid string}var newRs []newRfor rows.Next() {var current newRerr = rows.Scan(¤t.id, ¤t.eventid, ¤t.excel_id, ¤t.userid, ¤t.hallid)newRs = append(newRs, current)}// 在 `rows.Next()` 和 `rows.Scan(...)` 之后最好检查错误
请注意，我已经将代码中的 & 替换为 &，因为它是 HTML 实体编码的表示形式。
英文:
You do not need to create a local variables for each field, just create a struct and use it to read data into and use a slice to accumulate results:
// struct definition must be out of functions bodytype newR struct {id stringeventid stringexcel_id stringuserid stringhallid string}var newRs []newRfor rows.Next() {var current newRerr = rows.Scan(&current.id, &current.eventid, &current.excel_id, &current.userid, &current.hallid)newRs = append(newRs, r)}
And also it is better to check for errors after rows.Next() and rows.Scan(...).
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论