purchase notify, fix preview

app/core/models/node_storage.py

@@ -1,3 +1,4 @@
+import json
 from base58 import b58decode
 from sqlalchemy import Column, BigInteger, Integer, String, ForeignKey, DateTime, JSON, Boolean
 from sqlalchemy.orm import relationship
@@ -139,6 +140,13 @@ class StoredContent(AlchemyBase, AudioContentMixin):
             "created": spec_field_created,
             "updated": spec_field_updated,
         }
+    
+    def metadata_json(self, db_session):
+        metadata_cid = self.meta.get('metadata_cid')
+        if metadata_cid:
+            metadata_content = StoredContent.from_cid(db_session, metadata_cid)
+            with open(metadata_content.filepath, 'r') as f:
+                return json.loads(f.read())
 
     @classmethod
     def from_cid(cls, db_session, content_id):