Check for the existance of the function before trying to drop it.

At least on my machine, ignoring the error if the function doesn't exist
doesn't work since psycopg2 bombs.  So, we attempt to at least check if
there are any functions with a similar name before trying to drop it.
This way it should work better on an empty database where the function
has never existed.

Signed-off-by: Allan Lyons <Allan_Lyons@wycliffe.ca>

diff --git a/dak/dakdb/update3.py b/dak/dakdb/update3.py
index 406cc89b3212a59ead022c4037f29663f2f46932..5a5562fbedfe2659c5c2990f7ba125b3a25ac00c 100755 (executable)
--- a/dak/dakdb/update3.py
+++ b/dak/dakdb/update3.py
@@ -36,12 +36,15 @@ def do_update(self):
 
     try:
         c = self.db.cursor()
-        try:
-            # This might not exist on a fresh install, so don't fail
-            # needlessly
+        # The reason we try and check to see if it exists is that
+        # psycopg2 might leave the cursor invalid if the drop fails
+        c.execute("SELECT proname from pg_catalog.pg_proc WHERE proname = 'versioncmp'")
+        rows = c.fetchall()
+        if rows:
             c.execute("DROP FUNCTION versioncmp(text, text);")
-        except:
-            pass
+        else:
+            print "function already does not exist"
+
         c.execute("UPDATE config SET value = '3' WHERE name = 'db_revision'")
 
         self.db.commit()