1) Ensure that Calibres always uses the same names for tag and search categories.

2) Add code to verify the names are reserved. 
3) add compatibility names to the reserved words list
4) fix model to show the correct search label 'data' for the timestamp column
5) change internal naming of icons and user categories to avoid namespace collisions
6) fix get_categories to do the right thing with rating fields

src/calibre/ebooks/metadata/book/__init__.py

@@ -89,11 +89,18 @@ CALIBRE_METADATA_FIELDS = frozenset([
 )
 
 CALIBRE_RESERVED_LABELS = frozenset([
-    'search',  # reserved for saved searches
-    'date',
-    'all',
-    'ondevice',
-    'inlibrary',
+    'all',          # search term
+    'author_sort',  # can appear in device collection customization
+    'date',         # search term
+    'formats',      # search term
+    'inlibrary',    # search term
+    'news',         # search term
+    'ondevice',     # search term
+    'search',       # search term
+    'format',       # The next four are here for backwards compatibility
+    'tag',          # with searching. The terms can be used without the
+    'author',       # trailing 's'.
+    'comment',      # Sigh ...
     ]
 )
 

src/calibre/gui2/library/models.py

@@ -631,7 +631,10 @@ class BooksModel(QAbstractTableModel): # {{{
             if section >= len(self.column_map): # same problem as in data, the column_map can be wrong
                 return None
             if role == Qt.ToolTipRole:
-                return QVariant(_('The lookup/search name is "{0}"').format(self.column_map[section]))
+                ht = self.column_map[section]
+                if ht == 'timestamp': # change help text because users know this field as 'date'
+                    ht = 'date'
+                return QVariant(_('The lookup/search name is "{0}"').format(ht))
             if role == Qt.DisplayRole:
                 return QVariant(self.headers[self.column_map[section]])
             return NONE
@@ -730,11 +733,13 @@ class BooksModel(QAbstractTableModel): # {{{
 class OnDeviceSearch(SearchQueryParser): # {{{
 
     USABLE_LOCATIONS = [
-        'collections',
-        'title',
-        'author',
-        'format',
         'all',
+        'author',
+        'authors',
+        'collections',
+        'format',
+        'formats',
+        'title',
     ]
 
 

src/calibre/gui2/tag_view.py

@@ -14,8 +14,7 @@ from PyQt4.Qt import Qt, QTreeView, QApplication, pyqtSignal, \
                      QAbstractItemModel, QVariant, QModelIndex
 from calibre.gui2 import config, NONE
 from calibre.utils.config import prefs
-from calibre.utils.search_query_parser import saved_searches
-from calibre.library.database2 import Tag
+from calibre.ebooks.metadata.book import RESERVED_METADATA_FIELDS
 
 class TagsView(QTreeView): # {{{
 
@@ -204,17 +203,22 @@ class TagsModel(QAbstractItemModel): # {{{
         QAbstractItemModel.__init__(self, parent)
 
         # must do this here because 'QPixmap: Must construct a QApplication
-        # before a QPaintDevice'
-        self.category_icon_map = {'authors': QIcon(I('user_profile.svg')),
+        # before a QPaintDevice'. The ':' in front avoids polluting either the
+        # user-defined categories (':' at end) or columns namespaces (no ':').
+        self.category_icon_map = {
+                    'authors'   : QIcon(I('user_profile.svg')),
                     'series'    : QIcon(I('series.svg')),
                     'formats'   : QIcon(I('book.svg')),
-                    'publishers': QIcon(I('publisher.png')),
-                    'ratings':QIcon(I('star.png')),
+                    'publisher' : QIcon(I('publisher.png')),
+                    'rating'    : QIcon(I('star.png')),
                     'news'      : QIcon(I('news.svg')),
                     'tags'      : QIcon(I('tags.svg')),
-                    '*custom':QIcon(I('column.svg')),
-                    '*user':QIcon(I('drawer.svg')),
+                    ':custom'   : QIcon(I('column.svg')),
+                    ':user'     : QIcon(I('drawer.svg')),
                     'search'    : QIcon(I('search.svg'))}
+        for k in self.category_icon_map.keys():
+            if not k.startswith(':') and k not in RESERVED_METADATA_FIELDS:
+                raise ValueError('Tag category [%s] is not a reserved word.' %(k))
         self.icon_state_map = [None, QIcon(I('plus.svg')), QIcon(I('minus.svg'))]
         self.db = db
         self.search_restriction = ''
@@ -381,9 +385,9 @@ class TagsModel(QAbstractItemModel): # {{{
 
     def tokens(self):
         ans = []
-        tags_seen = []
+        tags_seen = set()
         for i, key in enumerate(self.row_map):
-            if key.endswith('*'): # User category, so skip it. The tag will be marked in its real category
+            if key.endswith(':'): # User category, so skip it. The tag will be marked in its real category
                 continue
             category_item = self.root_item.children[i]
             for tag_item in category_item.children:
@@ -394,10 +398,10 @@ class TagsModel(QAbstractItemModel): # {{{
                     if tag.name[0] == u'\u2605': # char is a star. Assume rating
                         ans.append('%s%s:%s'%(prefix, category, len(tag.name)))
                     else:
-                        if category == 'tag':
+                        if category == 'tags':
                             if tag.name in tags_seen:
                                 continue
-                            tags_seen.append(tag.name)
+                            tags_seen.add(tag.name)
                         ans.append('%s%s:"=%s"'%(prefix, category, tag.name))
         return ans
 

src/calibre/library/database2.py

@@ -37,6 +37,7 @@ from calibre.utils.ordered_dict import OrderedDict
 from calibre.utils.config import prefs
 from calibre.utils.search_query_parser import saved_searches
 from calibre.ebooks import BOOK_EXTENSIONS, check_ebook_format
+from calibre.ebooks.metadata.book import RESERVED_METADATA_FIELDS
 
 if iswindows:
     import calibre.utils.winshell as winshell
@@ -137,10 +138,10 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
                 ('formats',   {'table':None, 'column':None,
                                'type':None, 'is_multiple':False,
                                'kind':'standard', 'name':_('Formats')}),
-                ('publishers',{'table':'publishers', 'column':'name',
+                ('publisher', {'table':'publishers', 'column':'name',
                                'type':'text', 'is_multiple':False,
                                'kind':'standard', 'name':_('Publishers')}),
-                ('ratings',   {'table':'ratings', 'column':'rating',
+                ('rating',    {'table':'ratings', 'column':'rating',
                                'type':'rating', 'is_multiple':False,
                                'kind':'standard', 'name':_('Ratings')}),
                 ('news',      {'table':'news', 'column':'name',
@@ -152,6 +153,8 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         ]
         self.tag_browser_categories = OrderedDict()
         for k,v in tag_browser_categories_items:
+            if k not in RESERVED_METADATA_FIELDS:
+                raise ValueError('Tag category [%s] is not a reserved word.' %(k))
             self.tag_browser_categories[k] = v
 
         self.connect()
@@ -694,25 +697,25 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
                     if category in icon_map:
                         icon = icon_map[category]
                 elif self.tag_browser_categories[category]['kind'] == 'custom':
-                    icon = icon_map['*custom']
-                    icon_map[category] = icon_map['*custom']
+                    icon = icon_map[':custom']
+                    icon_map[category] = icon
                     tooltip = self.custom_column_label_map[category]['name']
 
             datatype = self.tag_browser_categories[category]['type']
             if datatype == 'rating':
-                item_zero_func = (lambda x: len(formatter(r[1])) > 0)
+                item_not_zero_func = (lambda x: x[1] > 0 and x[2] > 0)
                 formatter = (lambda x:u'\u2605'*int(round(x/2.)))
             elif category == 'authors':
-                item_zero_func = (lambda x: x[2] > 0)
+                item_not_zero_func = (lambda x: x[2] > 0)
                 # Clean up the authors strings to human-readable form
                 formatter = (lambda x: x.replace('|', ','))
             else:
-                item_zero_func = (lambda x: x[2] > 0)
+                item_not_zero_func = (lambda x: x[2] > 0)
                 formatter = (lambda x:x)
 
             categories[category] = [Tag(formatter(r[1]), count=r[2], id=r[0],
                                         icon=icon, tooltip = tooltip)
-                                    for r in data if item_zero_func(r)]
+                                    for r in data if item_not_zero_func(r)]
 
         # We delayed computing the standard formats category because it does not
         # use a view, but is computed dynamically
@@ -767,14 +770,14 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
                     items.append(taglist[label][name])
                 # else: do nothing, to not include nodes w zero counts
             if len(items):
-                cat_name = user_cat+'*' # add the * to avoid name collision
+                cat_name = user_cat+':' # add the ':' to avoid name collision
                 self.tag_browser_categories[cat_name] = {
                                 'table':None,  'column':None,
                                 'type':None,   'is_multiple':False,
                                 'kind':'user', 'name':user_cat}
                 # Not a problem if we accumulate entries in the icon map
                 if icon_map is not None:
-                    icon_map[cat_name] = icon_map['*user']
+                    icon_map[cat_name] = icon_map[':user']
                 if sort_on_count:
                     categories[cat_name] = \
                         sorted(items, cmp=(lambda x, y: cmp(y.count, x.count)))

src/calibre/utils/search_query_parser.py

@@ -22,7 +22,7 @@ from calibre.utils.pyparsing import Keyword, Group, Forward, CharsNotIn, Suppres
                       OneOrMore, oneOf, CaselessLiteral, Optional, NoMatch, ParseException
 from calibre.constants import preferred_encoding
 from calibre.utils.config import prefs
-
+from calibre.ebooks.metadata.book import RESERVED_METADATA_FIELDS
 
 '''
 This class manages access to the preference holding the saved search queries.
@@ -87,21 +87,25 @@ class SearchQueryParser(object):
     '''
 
     DEFAULT_LOCATIONS = [
-        'tag',
-        'title',
-        'author',
+        'all',
+        'author',       # compatibility
+        'authors',
+        'comment',      # compatibility
+        'comments',
+        'cover',
+        'date',
+        'format',       # compatibility
+        'formats',
+        'isbn',
+        'ondevice',
+        'pubdate',
         'publisher',
+        'search',
         'series',
         'rating',
-        'cover',
-        'comments',
-        'format',
-        'isbn',
-        'search',
-        'date',
-        'pubdate',
-        'ondevice',
-        'all',
+        'tag',          # compatibility
+        'tags',
+        'title',
                  ]
 
     @staticmethod
@@ -118,6 +122,9 @@ class SearchQueryParser(object):
         return failed
 
     def __init__(self, locations=None, test=False):
+        for k in self.DEFAULT_LOCATIONS:
+            if k not in RESERVED_METADATA_FIELDS:
+                raise ValueError('Search location [%s] is not a reserved word.' %(k))
         if locations is None:
             locations = self.DEFAULT_LOCATIONS
         self._tests_failed = False