Your Question
`type Status int
// Scan 实现 Scanner 接口，用于将数据库的值映射到枚举类型 func (s Status) Scan(value any) error { switch v := value.(type) { case int64: s = Status(value.(int64)) case []uint8: data := string(v) parseInt, _ := strconv.ParseInt(data, 10, 64) *s = Status(parseInt) default: return fmt.Errorf("unsupported scan type %T", value) } return nil }
// Value 实现 Valuer 接口，用于将枚举类型映射为数据库的值 func (s Status) Value() (driver.Value, error) { return s, nil }
type Users struct { Name string Type Status }
func main() { dsn := "root:123456@tcp(127.0.0.1:3306)/go_test?charset=utf8mb4&parseTime=True&loc=Local" db, err := gorm.Open(mysql.New(mysql.Config{ DSN: dsn}), &gorm.Config{}) if err != nil { panic(err) } err = db.AutoMigrate(&Users{}) if err != nil { return } var use []Users var uses []Users db.Table("users").Where("id = ?", 1).Find(&use) db.Find(&uses) `
db.Table("users").Where("id = ?", 1).Find(&use) ------- Scan value.(type) == int64
db.Find(&uses) ------ Scan value.(type) == []uint8
The document you expected this should be explained
Expected answer
I want to know why the input parameters of the scan method are different after executing these two lines of code.
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Comment From: paradox-lab2
I tried to reproduce the problem you described, however, Scan value.(type) in db.Find(&uses) is int64 but not []uint8.
the first step, i started mysql using docker:
docker run --name gorm7201 -e MYSQL_ROOT_PASSWORD=123456 -e MYSQL_DATABASE=go_test --rm -d -p 3306:3306 mysql:8.0.40
and then go run main.go.
here's my complete test code:
package main
import (
"database/sql/driver"
"fmt"
"gorm.io/driver/mysql"
"gorm.io/gorm"
"reflect"
"strconv"
)
type Status int
// Scan 实现 Scanner 接口，用于将数据库的值映射到枚举类型
func (s *Status) Scan(value any) error {
fmt.Println(value, reflect.TypeOf(value))
switch v := value.(type) {
case int64:
*s = Status(value.(int64))
case []uint8:
data := string(v)
parseInt, _ := strconv.ParseInt(data, 10, 64)
*s = Status(parseInt)
default:
return fmt.Errorf("unsupported scan type %T", value)
}
return nil
}
// Value 实现 Valuer 接口，用于将枚举类型映射为数据库的值
func (s Status) Value() (driver.Value, error) {
return s, nil
}
type Users struct {
ID uint
Name string
Type Status
}
func main() {
dsn := "root:123456@tcp(127.0.0.1:3306)/go_test?charset=utf8mb4&parseTime=True&loc=Local"
db, err := gorm.Open(mysql.New(mysql.Config{
DSN: dsn}), &gorm.Config{})
if err != nil {
panic(err)
}
err = db.AutoMigrate(&Users{})
if err != nil {
return
}
var count int64
db.Model(&Users{}).Count(&count)
if count == 0 {
// setup data
db.Exec(`
insert into go_test.users (id, name, type)
values (1, 'user1', 0),
(2, 'user2', 1),
(3, 'user3', 2),
(4, 'user4', 3),
(5, 'user5', 4),
(6, 'user6', 5),
(7, 'user7', 6),
(8, 'user8', 7),
(9, 'user9', 8),
(10, 'user10', 9);
`)
}
var use []Users
var uses []Users
db.Table("users").Where("id = ?", 1).Find(&use)
fmt.Println("-----------------------------------------------")
db.Find(&uses)
}
the output is
0 int64
-----------------------------------------------
0 int64
1 int64
2 int64
3 int64
4 int64
5 int64
6 int64
7 int64
8 int64
9 int64
dependencies version
gorm.io/driver/mysql v1.5.7
gorm.io/gorm v1.25.12