feat: expose custom columns as category elements in OPDS feed

Co-authored-by: Vijay Kalambekar <vijaykalambekar-external@worldfamilyenglish.com>

Author: vijaykalam

cps/db.py

@@ -436,6 +436,24 @@ def __repr__(self):
     def atom_timestamp(self):
         return self.timestamp.strftime('%Y-%m-%dT%H:%M:%S+00:00') or ''
 
+    @property
+    def custom_extra_fill(self):
+        out = []
+        for col_id in cc_classes:
+            val = getattr(self, 'custom_column_' + str(col_id), None)
+            if val:
+                col_def = CalibreDB.session_factory().query(CustomColumns).filter(CustomColumns.id == col_id).first()
+                name = col_def.name if col_def else "Column {}".format(col_id)
+                values = val if isinstance(val, list) else [val]
+                for item in values:
+                    if hasattr(item, 'value'):
+                        out.append({
+                            'name': name,
+                            'value': item.value
+                        })
+        return out
+
+
     @property
     def isbn(self):
         for identifier in self.identifiers:

cps/templates/feed.xml

@@ -63,6 +63,11 @@
               term="{{tag.name}}"
               label="{{tag.name}}"/>
     {% endfor %}
+    {% for cc in entry.Books.custom_extra_fill %}
+    <category scheme="custom_column:{{cc.name}}"
+              term="{{cc.name}}"
+              label="{{cc.value}}"/>
+    {% endfor %}
     {% if entry.Books.comments[0] %}<summary>{{entry.Books.comments[0].text|striptags}}</summary>{% endif %}
     {% if entry.Books.has_cover %}
     <link type="image/jpeg" href="{{url_for('opds.feed_get_cover', book_id=entry.Books.id)}}" rel="http://opds-spec.org/image"/>