Improve performance when testing if user owns an album

This is done by querying parent albums instead of sub-albums,
which changes the runtime from exponential to linear time.

This fixes #388

api/graphql/models/album.go

@@ -54,3 +54,27 @@ func GetChildrenFromAlbums(db *gorm.DB, filter func(*gorm.DB) *gorm.DB, albumIDs
 
 	return children, err
 }
+
+func (a *Album) GetParents(db *gorm.DB, filter func(*gorm.DB) *gorm.DB) (parents []*Album, err error) {
+	return GetParentsFromAlbums(db, filter, a.ID)
+}
+
+func GetParentsFromAlbums(db *gorm.DB, filter func(*gorm.DB) *gorm.DB, albumID int) (parents []*Album, err error) {
+	query := db.Model(&Album{}).Table("super_albums")
+
+	if filter != nil {
+		query = filter(query)
+	}
+
+	err = db.Raw(`
+	WITH recursive super_albums AS (
+		SELECT * FROM albums AS leaf WHERE id = ?
+		UNION ALL
+		SELECT parent.* from albums AS parent JOIN super_albums ON parent.id = super_albums.parent_album_id
+	)
+
+	?
+	`, albumID, query).Find(&parents).Error
+
+	return parents, err
+}

api/graphql/models/album_test.go

@@ -8,7 +8,7 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestAlbumGetChildren(t *testing.T) {
+func TestAlbumGetChildrenAndParents(t *testing.T) {
 	db := test_utils.DatabaseTest(t)
 
 	rootAlbum := models.Album{
@@ -51,43 +51,73 @@ func TestAlbumGetChildren(t *testing.T) {
 		return
 	}
 
-	root_children, err := rootAlbum.GetChildren(db, nil)
-	if !assert.NoError(t, err) {
-		return
-	}
+	verifyResult := func(t *testing.T, expected_albums []*models.Album, result []*models.Album) {
+		assert.Equal(t, len(expected_albums), len(result))
 
-	expected_children := []*models.Album{
-		{
-			Title: "root",
-			Path:  "/photos",
-		},
-		{
-			Title: "child1",
-			Path:  "/photos/child1",
-		},
-		{
-			Title: "child2",
-			Path:  "/photos/child2",
-		},
-		{
-			Title: "subchild",
-			Path:  "/photos/child1/subchild",
-		},
+		for _, expected := range expected_albums {
+			found_expected := false
+			for _, item := range result {
+				if item.Title == expected.Title && item.Path == expected.Path {
+					found_expected = true
+					break
+				}
+			}
+			if !found_expected {
+				assert.Failf(t, "albums did not match", "expected to find item: %v", expected)
+			}
+		}
 	}
 
-	assert.Equal(t, len(expected_children), len(root_children))
+	t.Run("Album get children", func(t *testing.T) {
+		root_children, err := rootAlbum.GetChildren(db, nil)
+		if !assert.NoError(t, err) {
+			return
+		}
 
-	for _, expected := range expected_children {
-		found_expected := false
-		for _, item := range root_children {
-			if item.Title == expected.Title && item.Path == expected.Path {
-				found_expected = true
-				break
-			}
+		expected_children := []*models.Album{
+			{
+				Title: "root",
+				Path:  "/photos",
+			},
+			{
+				Title: "child1",
+				Path:  "/photos/child1",
+			},
+			{
+				Title: "child2",
+				Path:  "/photos/child2",
+			},
+			{
+				Title: "subchild",
+				Path:  "/photos/child1/subchild",
+			},
+		}
+
+		verifyResult(t, expected_children, root_children)
+	})
+
+	t.Run("Album get parents", func(t *testing.T) {
+		parents, err := sub_child.GetParents(db, nil)
+		if !assert.NoError(t, err) {
+			return
 		}
-		if !found_expected {
-			assert.Failf(t, "root children did not match", "expected to find item: %v", expected)
+
+		expected_parents := []*models.Album{
+			{
+				Title: "root",
+				Path:  "/photos",
+			},
+			{
+				Title: "child1",
+				Path:  "/photos/child1",
+			},
+			{
+				Title: "subchild",
+				Path:  "/photos/child1/subchild",
+			},
 		}
-	}
+
+		verifyResult(t, expected_parents, parents)
+	})
 
 }

api/graphql/models/user.go

@@ -175,13 +175,13 @@ func (user *User) OwnsAlbum(db *gorm.DB, album *Album) (bool, error) {
 	}
 
 	filter := func(query *gorm.DB) *gorm.DB {
-		return query.Where("id = ?", album.ID)
+		return query.Where("id IN (?)", albumIDs)
 	}
 
-	ownedAlbum, err := GetChildrenFromAlbums(db, filter, albumIDs)
+	ownedParents, err := album.GetParents(db, filter)
 	if err != nil {
 		return false, err
 	}
 
-	return len(ownedAlbum) > 0, nil
+	return len(ownedParents) > 0, nil
 }