photoview/api/graphql/models/album.go

package models

import (
	"crypto/md5"
	"encoding/hex"

	"gorm.io/gorm"
)

type Album struct {
	Model
	Title         string `gorm:"not null"`
	ParentAlbumID *int   `gorm:"index"`
	ParentAlbum   *Album `gorm:"constraint:OnDelete:SET NULL;"`
	// OwnerID       int `gorm:"not null"`
	// Owner         User
	Owners   []User `gorm:"many2many:user_albums;constraint:OnDelete:CASCADE;"`
	Path     string `gorm:"not null"`
	PathHash string `gorm:"unique"`
}

func (a *Album) FilePath() string {
	return a.Path
}

func (a *Album) BeforeSave(tx *gorm.DB) (err error) {
	hash := md5.Sum([]byte(a.Path))
	a.PathHash = hex.EncodeToString(hash[:])
	return nil
}

// GetChildren performs a recursive query to get all the children of the album.
// An optional filter can be provided that can be used to modify the query on the children.
func (a *Album) GetChildren(db *gorm.DB, filter func(*gorm.DB) *gorm.DB) (children []*Album, err error) {
	return GetChildrenFromAlbums(db, filter, []int{a.ID})
}

func GetChildrenFromAlbums(db *gorm.DB, filter func(*gorm.DB) *gorm.DB, albumIDs []int) (children []*Album, err error) {
	query := db.Model(&Album{}).Table("sub_albums")

	if filter != nil {
		query = filter(query)
	}

	err = db.Raw(`
	WITH recursive sub_albums AS (
		SELECT * FROM albums AS root WHERE id IN (?)
		UNION ALL
		SELECT child.* FROM albums AS child JOIN sub_albums ON child.parent_album_id = sub_albums.id
	)

	?
	`, albumIDs, query).Find(&children).Error

	return children, err
}