Golangのgormで、PrimaryKeyにUUIDを使う ref: http://qiita.com/roothybrid7/items/dc58bae01f941e1a72be

file0.txt

// gorm.Model
//type Model struct {
//    ID        uint64 `gorm:"primary_key"`
//    CreatedAt time.Time
//    UpdatedAt time.Time
//    DeletedAt *time.Time
//}

type User struct {
    gorm.Model
    Name string
}

model.go

var (
    reqKey        private
    UUIDGenerator = func(db *gorm.DB) UUID {
        var uuid uint64
        db.Unscoped().Raw("SELECT UUID_SHORT()").Row().Scan(&uuid)
        return UUID(uuid)
    }
)

// MARK: Gorm callbacks

func UpdateUUIDWhenCreate(scope *gorm.Scope) {
    if !scope.HasError() {
        scope.SetColumn("UUID", UUIDGenerator(scope.DB())) // Primary Key
    }
}

func init() {
    // XXX: DBのtimestampをUTCにする
    gorm.NowFunc = util.NowUtcFunc
gorm.DefaultCallback.Create().Before("gorm:save_before_associations").Register("myapp:update_uuid_when_create", UpdateUUIDWhenCreate)
}

user.go

type User struct {
    //gorm.Model        // see: https://github.com/jinzhu/gorm#conventions
    SoftModel
    Username       string          `sql:"size:180;not null;index" json:"username"`

uuid.go

package typedef

import (
    "errors"
    "strconv"
)

// UUIDは、RDBではuint64で保存するが、
// APIのレスポンスやRedisでは16進数の文字列に変換して返すためのType
type UUID uint64

func (u UUID) IsZero() bool {
    return u == 0
}

func (u UUID) MarshalJSON() ([]byte, error) {
    hex := UintToHex(u)
    if hex != "" {
        return []byte(`"` + UintToHex(u) + `"`), nil
    }
    return nil, errors.New("UUID.MarshalText: invalid value")
}

// TODO: 多分タブルクオートを先にトリミングする必要がある
func (u *UUID) UnmarshalJSON(data []byte) (err error) {
    i := UUID(UintFromHex(string(data)))
    u = &i
    return
}

func (u UUID) MarshalText() ([]byte, error) {
    hex := UintToHex(u)
    if hex != "" {
        return []byte(UintToHex(u)), nil
    }
    return nil, errors.New("UUID.MarshalText: invalid value")
}

func (u *UUID) UnmarshalText(data []byte) (err error) {
    i := UUID(UintFromHex(string(data)))
    u = &i
    return
}

func (u UUID) ToHex() string {
    return strconv.FormatUint(uint64(u), 16)
}

// MARK: Helpers

func UintToHex(i interface{}) string {
    switch v := i.(type) {
    case uint64:
        return strconv.FormatUint(v, 16)
    case UUID:
        return strconv.FormatUint(uint64(v), 16)
    }
    return ""
}

func UintFromHex(hex string) uint64 {
    if num, err := strconv.ParseUint(hex, 16, 64); err != nil {
        return 0
    } else {
        return num
    }
}