SQL选择查询的循环结果

Question

So am learning Go - Language atm and I still confused on how do I iterate arraylist that I get from SQL when I execute my query

here is for the detail

I got a file named CustomerDao.go which contains a bunch of queries and the query I uses now is

SELECT mst_customer.mcus_mlok_pk , mst_customer.mcus_mlok_kode , mst_customer.mcus_nama FROM frontend.mst_customer;

which will return 50 rows of data and 3 columns yes? now the confusing part is when I reach my controller which is like this

func GetArrayListCustomer(queryType string) (map[string]CustomerModelResponse, error) {
    logger := customlogger.GetInstance()
    logger.Println("Service: GetArrayListCustomer Start")

    queryText := dao.CustomerDAO(queryType)
    res, err := config.GetDbByPath("myDatabase").GetDb().Query(queryText)

    mapList := make(map[string]CustomerModelResponse)
    var custResponse CustomerModelResponse

    if config.FancyHandleError(err) {
        logger.Println("Service: GetArrayListCustomer -> Error " + err.Error())
        return mapList, err
    }
    defer res.Close()
    for res.Next() {
        errs := res.Scan(&custResponse.McusmlokPk, &custResponse.McusmlokKode, &custResponse.McusNama)
        for _, eachCust := range res {
            //the error goes here , for some reason
        }
    }
    return mapList, nil
}

and then I try to loop the value then the error show that I cannot range over res which is a *sql.Rows how do I declare those result as an array not as a *sql.Rows type?

Answer 1

You need to scan your values into a struct, using rows.Next you loop over the sql results your query gives, you need to scan those results (on each loop) into your desired struct, and save that struct into something (a map in this case)

func GetArrayListCustomer(queryType string) (map[string]CustomerModelResponse, error) {
    logger := customlogger.GetInstance()
    logger.Println("Service: GetArrayListCustomer Start")

    queryText := dao.CustomerDAO(queryType)
    res, err := config.GetDbByPath("myDatabase").GetDb().Query(queryText)

    mapList := make(map[string]CustomerModelResponse)

    if config.FancyHandleError(err) {
        logger.Println("Service: GetArrayListCustomer -> Error " + err.Error())
        return mapList, err
    }
    defer res.Close()
    for res.Next() {
        var custResponse CustomerModelResponse
        if err := res.Scan(&custResponse.McusmlokPk, &custResponse.McusmlokKode, &custResponse.McusNama); err != nil {
            // Handle error
        }
        mapList[cutResponse.McusmlokPk] = custResponse
    }
    // Now mapList is a map with McusmlokPk as key and CustomerModelResponse struct as value
    return mapList, nil
}