Ensure that empty subtitles - ie those with a value of None - are set…

… to null in the database rather than the string "None" (#2249)

alembic/versions/20250114_c800cc42184a_set_none_subtitles_to_null.py

@@ -0,0 +1,23 @@
+"""Set none subtitles to null
+
+Revision ID: c800cc42184a
+Revises: 579786fecbf4
+Create Date: 2025-01-14 18:36:21.116427+00:00
+
+"""
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "c800cc42184a"
+down_revision = "579786fecbf4"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.execute("update editions set subtitle = null where subtitle = 'None'")
+
+
+def downgrade() -> None:
+    pass

src/palace/manager/core/opds2_import.py

@@ -630,7 +630,11 @@ def _extract_publication_metadata(
         self.log.debug(f"Started extracting metadata from publication {publication}")
 
         title = str(publication.metadata.title)
-        subtitle = str(publication.metadata.subtitle)
+        subtitle = (
+            str(publication.metadata.subtitle)
+            if publication.metadata.subtitle
+            else None
+        )
 
         languages = first_or_default(publication.metadata.languages)
         derived_medium = self._extract_medium_from_links(publication.links)