From a65f241258bec1cc6ad9643c701d178c0659ac8b Mon Sep 17 00:00:00 2001
From: Damien Elmes <git@ichi2.net>
Date: Fri, 29 Apr 2011 11:46:26 +0900
Subject: [PATCH] gracefully handle invalid queries

---
 anki/find.py       | 5 ++++-
 tests/test_find.py | 2 ++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/anki/find.py b/anki/find.py
index fe8afcd8e..3891e2f6f 100644
--- a/anki/find.py
+++ b/anki/find.py
@@ -157,7 +157,10 @@ order by %s""" % (lim, sort)
             cond = "c.id in (select id from cards order by mod desc limit 100)"
         if neg:
             cond = "not (%s)" % cond
-        self.lims['card'].append(cond)
+        if cond:
+            self.lims['card'].append(cond)
+        else:
+            self.lims['valid'] = False
 
     def _findText(self, val, neg, c):
         val = val.replace("*", "%")
diff --git a/tests/test_find.py b/tests/test_find.py
index 0434b5985..7e0f8fb87 100644
--- a/tests/test_find.py
+++ b/tests/test_find.py
@@ -110,6 +110,8 @@ def test_findCards():
     assert len(deck.findCards("helloworld", full=True)) == 1
     assert len(deck.findCards("front:helloworld")) == 0
     assert len(deck.findCards("front:helloworld", full=True)) == 1
+    # searching for an invalid special tag should not error
+    assert len(deck.findCards("is:invalid")) == 0
 
 def test_findReplace():
     deck = getEmptyDeck()