如何将MySQL TIMESTAMP值扫描（）到time.Time变量中？

Question

I have this Go code:

package main

import (
    "fmt"
    "database/sql"
    _"github.com/go-sql-driver/mysql"
    "time"
)

type User struct {
    id                  uint32
    name                string
    email               string
    rating              uint8
    subscription        uint8
    date_registered     time.Time
    online              string
}

// main entry point
func main() {
    // setup db connection
    db, err := sql.Open("mysql", "user:@tcp(127.0.0.1:3306)/c9?parseTime=true")
    if err != nil {
        fmt.Println(err)
    }
    defer db.Close()

    // query
    rows, err := db.Query("SELECT * FROM users WHERE id = ?", 1)
    if err != nil {
        fmt.Println(err)
    }
    defer rows.Close()

    usr := User{}
    for rows.Next() {
        err := rows.Scan(&usr.id, &usr.name, &usr.email, &usr.rating, &usr.subscription, &usr.date_registered, &usr.online)
        if err != nil {
            fmt.Println(err)
        }
    }
    fmt.Println(usr)
    err = rows.Err()
    if err != nil {
        fmt.Println(err)
    }
}

This is what I get from MySQL console:

mysql> describe users;
+-----------------+---------------------+------+-----+-------------------+----------------+
| Field           | Type                | Null | Key | Default           | Extra          |
+-----------------+---------------------+------+-----+-------------------+----------------+
| id              | int(10) unsigned    | NO   | PRI | NULL              | auto_increment |
| name            | varchar(50)         | NO   |     | NULL              |                |
| email           | varchar(50)         | NO   |     | NULL              |                |
| rating          | tinyint(3) unsigned | YES  |     | NULL              |                |
| subscription    | tinyint(3) unsigned | NO   |     | 0                 |                |
| date_registered | timestamp           | NO   |     | CURRENT_TIMESTAMP |                |
| online          | char(1)             | NO   |     | N                 |                |
+-----------------+---------------------+------+-----+-------------------+----------------+
7 rows in set (0.00 sec)

mysql> SELECT * FROM users;
+----+------------+-----------------------+--------+--------------+---------------------+--------+
| id | name       | email                 | rating | subscription | date_registered     | online |
+----+------------+-----------------------+--------+--------------+---------------------+--------+
|  1 | alakhazamm | [e-mail] |   NULL |            0 | 2014-10-28 15:37:44 | N      |
+----+------------+-----------------------+--------+--------------+---------------------+--------+
1 row in set (0.00 sec)

---

After .Scan(), fmt.Println(usr) prints

{1 alakhazamm [e-mail] 0 0 {0 0 <nil>} }

The last two fields of the struct are wrong but I have no idea why. I've tried using date_registered string in the struct definition, but I get an empty string after .Scan(). I've also read in the driver's docs that ?parseTime=true parses MySQL DATE and DATETIME values into time.Time, but they don't mention TIMESTAMP which is what I'm currently using.

Am I missing something important or is it a bug/missing feature of the library?

Answer 1

I've found the cause of the error.

Since rating is NULL in the database, the scanner gave the error

sql: Scan error on column index 3: converting string "nil" to a uint8: strconv.ParseUint: parsing "nil": invalid syntax

I've updated the database row and now usr.date_registered and usr.online hold the correct values.

I guess I'll have to make the MySQL field NOT NULL and just use -1 to indicate a non-initialised value.