Composite column based categories

src/calibre/db/categories.py

@@ -135,11 +135,19 @@ def get_categories(dbcache, sort='name', book_ids=None, icon_map=None):
 
     categories = {}
     book_ids = frozenset(book_ids) if book_ids else book_ids
+    get_metadata = partial(dbcache._get_metadata, get_user_categories=False)
+    bids = None
+
     for category, is_multiple, is_composite in find_categories(fm):
         tag_class = create_tag_class(category, fm, icon_map)
         # TODO: Handle composite column based categories (both is_multiple and
         # not is_multiple)
-        if category == 'news':
+        if is_composite:
+            if bids is None:
+                bids = dbcache._all_book_ids() if book_ids is None else book_ids
+            cats = dbcache.fields[category].get_composite_categories(
+                tag_class, book_rating_map, bids, is_multiple, get_metadata)
+        elif category == 'news':
             cats = dbcache.fields['tags'].get_news_category(tag_class, book_ids)
         else:
             cats = dbcache.fields[category].get_categories(

src/calibre/db/fields.py

@@ -186,6 +186,25 @@ class CompositeField(OneToOneField):
         for val, book_ids in val_map.iteritems():
             yield val, book_ids
 
+    def get_composite_categories(self, tag_class, book_rating_map, book_ids,
+                                 is_multiple, get_metadata):
+        ans = []
+        id_map = defaultdict(set)
+        for book_id in book_ids:
+            val = self.get_value_with_cache(book_id, get_metadata)
+            vals = [x.strip() for x in val.split(is_multiple)] if is_multiple else [val]
+            for val in vals:
+                if val:
+                    id_map[val].add(book_id)
+        for item_id, item_book_ids in id_map.iteritems():
+            ratings = tuple(r for r in (book_rating_map.get(book_id, 0) for
+                                        book_id in item_book_ids) if r > 0)
+            avg = sum(ratings)/len(ratings) if ratings else 0
+            c = tag_class(item_id, id=item_id, sort=item_id, avg=avg,
+                            id_set=item_book_ids, count=len(item_book_ids))
+            ans.append(c)
+        return ans
+
 class OnDeviceField(OneToOneField):
 
     def __init__(self, name, table):

src/calibre/db/tables.py

@@ -98,10 +98,10 @@ class CompositeTable(OneToOneTable):
         self.book_col_map = {}
         d = self.metadata['display']
         self.composite_template = ['composite_template']
-        self.contains_html = d['contains_html']
+        self.contains_html = d.get('contains_html', False)
-        self.make_category = d['make_category']
+        self.make_category = d.get('make_category', False)
-        self.composite_sort = d['composite_sort']
+        self.composite_sort = d.get('composite_sort', False)
-        self.use_decorations = d['use_decorations']
+        self.use_decorations = d.get('use_decorations', False)
 
 class ManyToOneTable(Table):