fed notes

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CRUD ​

Read / Select ​

分页 ​

go
func (s *AppRepository) GetAppList(ctx context.Context, page int, size int) ([]AppDTO, int64, error) {
	var apps []model.App
	var total int64

	db := s.db.WithContext(ctx).Model(&model.App{})

	if err := db.Count(&total).Error; err != nil {
		return nil, 0, err
	}

	if err := db.Offset((page - 1) * size).
		Limit(size).
		Find(&apps).Error; err != nil {
		return nil, 0, err
	}

	return ToAppList(apps), total, nil
}

Exists ​

go
func (s *UserRepository) ExistsByEmail(ctx context.Context, email string) (bool, error) {

	var count int64
	err := s.db.WithContext(ctx).Model(&model.User{}).Where("email = ?", email).Count(&count).Error

	if err != nil {
		return false, err
	}
	// fmt.Println("count > ", count)

	if count > 0 {
		return true, nil
	}

	return false, nil
}

未成功

First/Take/Last：未命中会返回 ErrRecordNotFound

Find：未命中通常不报错，只是结果为空（切片长度 0）

go
func (s *UserRepository) ExistsByEmail(ctx context.Context, email string) (bool, error) {
	// 如果查不到，err 就一定会是 gorm.ErrRecordNotFound
	_, err := gorm.G[model.User](s.db).Where("email = ?", email).First(ctx)

	if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
		return false, err
	}

	return true, nil
}

Create ​

todo

Update ​

todo

Delete ​

GORM 默认就是软删

go
func DeleteApp(ctx context.Context, id uint) error {
	return db.GetInstance().WithContext(ctx).Where("id = ?", id).Delete(&model.App{}).Error
}

硬删：

go
// 软删与硬删的区别仅仅只是 Unscoped()
func DeleteApp(ctx context.Context, id uint) error {
	return db.GetInstance().WithContext(ctx).Unscoped().Where("id = ?", id).Delete(&model.App{}).Error
}