[gnome-music] query: rework playlists query

[Carlos Garnacho <carlosg src gnome org>]

commit 120b275c4e5b601d3c97dd940f64358eebd6de3c
Author: Carlos Garnacho <carlosg gnome org>
Date:   Wed Dec 30 12:07:18 2015 +0100

    query: rework playlists query
    
    No need to deep nest filters and optionals, it can all be done in
    the main query.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=759587

 gnomemusic/query.py |   21 ++++++---------------
 1 files changed, 6 insertions(+), 15 deletions(-)
---
diff --git a/gnomemusic/query.py b/gnomemusic/query.py
index 3a7fc58..a3a6aa4 100644
--- a/gnomemusic/query.py
+++ b/gnomemusic/query.py
@@ -252,24 +252,15 @@ class Query():
         nfo:entryCounter(?playlist) AS childcount
         {
             %(where_clause)s
+            ?playlist a nmm:Playlist .
             OPTIONAL {
-                ?playlist a nfo:FileDataObject .
-                FILTER (
-                    EXISTS {
-                        ?playlist tracker:available 'true'
-                        FILTER (
-                            tracker:uri-is-descendant(
-                                '%(music_dir)s', nie:url(?playlist)
-                            ) ||
-                            tracker:uri-is-descendant(
-                                '%(download_dir)s', nie:url(?playlist)
-                            )
-                        )
-                    }
-                )
+                ?playlist nie:url ?url ;
+                          tracker:available true .
+            FILTER (STRSTARTS (?url, '%(download_dir)s/') ||
+                    STRSTARTS (?url, '%(music_dir)s/'))
             }
         }
-    ORDER BY fn:lower-case(?title)
+    ORDER BY LCASE(?title)
     '''.replace('\n', ' ').strip() % {
             'where_clause': where_clause.replace('\n', ' ').strip(),
             'music_dir': Query.MUSIC_URI,