Add the news category

src/calibre/db/categories.py

@@ -53,8 +53,7 @@ class Tag(object):
 
 def find_categories(field_metadata):
     for category, cat in field_metadata.iteritems():
-        if (cat['is_category'] and cat['kind'] not in {'user', 'search'} and
-            category != 'news'):
+        if (cat['is_category'] and cat['kind'] not in {'user', 'search'}):
             yield (category, cat['is_multiple'].get('cache_to_list', None), False)
         elif (cat['datatype'] == 'composite' and
               cat['display'].get('make_category', False)):
@@ -102,8 +101,11 @@ def get_categories(dbcache, sort='name', book_ids=None, icon_map=None):
     book_ids = frozenset(book_ids) if book_ids else book_ids
     for category, is_multiple, is_composite in find_categories(fm):
         tag_class = create_tag_class(category, fm, icon_map)
-        cats = dbcache.fields[category].get_categories(
-            tag_class, book_rating_map, lang_map, book_ids)
+        if category == 'news':
+            cats = dbcache.fields['tags'].get_news_category(tag_class, book_ids)
+        else:
+            cats = dbcache.fields[category].get_categories(
+                tag_class, book_rating_map, lang_map, book_ids)
         if sort == 'popularity':
             key=attrgetter('count')
         elif sort == 'rating':

src/calibre/db/fields.py

@@ -441,6 +441,34 @@ class SeriesField(ManyToOneField):
         val = self.table.id_map[item_id]
         return title_sort(val, order=tss, lang=lang)
 
+class TagsField(ManyToManyField):
+
+    def get_news_category(self, tag_class, book_ids=None):
+        news_id = None
+        ans = []
+        for item_id, val in self.table.id_map.iteritems():
+            if val == _('News'):
+                news_id = item_id
+                break
+        if news_id is None:
+            return ans
+
+        news_books = self.table.col_book_map[news_id]
+        if book_ids is not None:
+            news_books = news_books.intersection(book_ids)
+        if not news_books:
+            return ans
+        for item_id, item_book_ids in self.table.col_book_map.iteritems():
+            item_book_ids = item_book_ids.intersection(news_books)
+            if item_book_ids:
+                name = self.category_formatter(self.table.id_map[item_id])
+                if name == _('News'):
+                    continue
+                c = tag_class(name, id=item_id, sort=name,
+                              id_set=item_book_ids, count=len(item_book_ids))
+                ans.append(c)
+        return ans
+
 def create_field(name, table):
     cls = {
             ONE_ONE : OneToOneField,
@@ -455,6 +483,8 @@ def create_field(name, table):
         cls = FormatsField
     elif name == 'identifiers':
         cls = IdentifiersField
+    elif name == 'tags':
+        cls = TagsField
     elif table.metadata['datatype'] == 'composite':
         cls = CompositeField
     elif table.metadata['datatype'] == 'series':