Add BeforeSave hook for type for duplicate detection

db/type.go

@@ -1,10 +1,42 @@
 package db
 
-import "gorm.io/gorm"
+import (
+	"errors"
+
+	"gorm.io/gorm"
+)
 
 type Type struct {
 	gorm.Model
 	Name    string
 	Comment string
 	Color   string
+	UserID  uint
+	User    *User
+}
+
+var (
+	ERROR_TYPE_NAME_EMPTY      = errors.New("The 'Name' field of 'Type' cannot be empty")
+	ERROR_TYPE_NAME_NOT_UNIQUE = errors.New("The 'Name' field of 'Type' have to be unique for user")
+)
+
+func (t *Type) BeforeSave(tx *gorm.DB) error {
+	if t.Name == "" {
+		return ERROR_TYPE_NAME_EMPTY
+	}
+
+	var dup Type
+	if err := tx.Find(&dup, Type{Name: t.Name, UserID: t.UserID}).Error; err != nil {
+		return err
+	}
+
+	if t.ID != dup.ID && dup.ID != 0 {
+		return ERROR_TYPE_NAME_NOT_UNIQUE
+	}
+
+	return nil
+}
+
+func (t *Type) GetID() uint {
+	return t.ID
 }