From fcbe0466a6eee8d76aa4aec23e5cc6f5de1a59d8 Mon Sep 17 00:00:00 2001
From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Fri, 4 Mar 2011 20:30:43 +0000
Subject: [PATCH] Correctly detect an empty query sent to the backend

Closes ticket #46.
---
 NEWS                 | 6 ++++++
 psycopg/pqpath.c     | 7 +++++++
 tests/test_cursor.py | 6 ++++++
 3 files changed, 19 insertions(+)

diff --git a/NEWS b/NEWS
index a7e634e3..1eea8af6 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,9 @@
+What's new in psycopg 2.4.1
+---------------------------
+
+  - Correctly detect an empty query sent to the backend (ticket #46).
+
+
 What's new in psycopg 2.4
 -------------------------
 
diff --git a/psycopg/pqpath.c b/psycopg/pqpath.c
index 1a5278b5..8d144dce 100644
--- a/psycopg/pqpath.c
+++ b/psycopg/pqpath.c
@@ -1359,6 +1359,13 @@ pq_fetch(cursorObject *curs)
         /* don't clear curs->pgres, because it contains the results! */
         break;
 
+    case PGRES_EMPTY_QUERY:
+        PyErr_SetString(ProgrammingError,
+            "can't execute an empty query");
+        IFCLEARPGRES(curs->pgres);
+        ex = -1;
+        break;
+
     default:
         Dprintf("pq_fetch: uh-oh, something FAILED: pgconn = %p", curs->conn);
         pq_raise(curs->conn, curs, NULL);
diff --git a/tests/test_cursor.py b/tests/test_cursor.py
index 1860ddc6..836f710d 100755
--- a/tests/test_cursor.py
+++ b/tests/test_cursor.py
@@ -37,6 +37,12 @@ class CursorTests(unittest.TestCase):
     def tearDown(self):
         self.conn.close()
 
+    def test_empty_query(self):
+        cur = self.conn.cursor()
+        self.assertRaises(psycopg2.ProgrammingError, cur.execute, "")
+        self.assertRaises(psycopg2.ProgrammingError, cur.execute, " ")
+        self.assertRaises(psycopg2.ProgrammingError, cur.execute, ";")
+
     def test_executemany_propagate_exceptions(self):
         conn = self.conn
         cur = conn.cursor()