Fix #1605: parsing bare + and - in queries

beets/dbcore/queryparse.py

@@ -188,7 +188,11 @@ def parse_sorted_query(model_cls, parts, prefixes={}):
             ))
             del subquery_parts[:]
         else:
-            if part.endswith((u'+', u'-')) and u':' not in part:
+            # Sort parts (1) end in + or -, (2) don't have a field, and
+            # (3) consist of more than just the + or -.
+            if part.endswith((u'+', u'-')) \
+                    and u':' not in part \
+                    and len(part) > 1:
                 sort_parts.append(part)
             else:
                 subquery_parts.append(part)

docs/changelog.rst

@@ -47,6 +47,8 @@ Fixes:
   encounters an error. :bug:`1592`
 * Case-insensitive path queries might have returned nothing because of a
   wrong SQL query.
+* Fix a crash when a query contains a "+" or "-" alone in a component.
+  :bug:`1605`
 
 
 1.3.14 (August 2, 2015)

test/test_dbcore.py

@@ -518,6 +518,12 @@ def test_leading_comma_or_query(self):
         self.assertIsInstance(s, dbcore.query.NullSort)
         self.assertEqual(len(q.subqueries), 3)
 
+    def test_only_direction(self):
+        q, s = self.psq('-')
+        self.assertIsInstance(q, dbcore.query.AndQuery)
+        self.assertIsInstance(s, dbcore.query.NullSort)
+        self.assertEqual(len(q.subqueries), 1)
+
 
 class ResultsIteratorTest(unittest.TestCase):
     def setUp(self):