diff --git a/data/user.go b/data/user.go
index cff1d2a..7efe964 100644
--- a/data/user.go
+++ b/data/user.go
@@ -5,7 +5,7 @@ import "github.com/google/uuid"
 type User struct {
 	Id       uint      `json:"id" gorm:"primarykey;autoincrement"`
 	UUID     uuid.UUID `json:"uuid" gorm:"type:uuid;uniqueindex;not null"`
-	UserId   string    `json:"user_id" gorm:"size:8;uniqueindex;not null"`
+	UserId   uuid.UUID `json:"user_id" gorm:"size:8;uniqueindex;not null"`
 	Email    string    `json:"email" gorm:"uniqueindex;not null"`
 	Nickname string    `json:"nickname" gorm:"not null"`
 	Type     string    `json:"type" gorm:"not null"`
@@ -20,3 +20,12 @@ func (self *User) GetByEmail(email string) error {
 	}
 	return nil
 }
+
+func (self *User) SetCheckinState(email string, state bool) error {
+	if err := Database.Where("email = ?", email).First(&self).Error; err != nil {
+		return err
+	}
+	self.Checkin = state
+	Database.Save(&self)
+	return nil
+}