From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Fri, 12 Feb 2021 02:21:35 +0000 (+0100)
Subject: Set up row maker and loaders only once in a server-side cursor lifetime
X-Git-Tag: 3.0.dev0~106^2~16
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=88ac162dfa1d5fa8116c023ff06f057e8885136b;p=thirdparty%2Fpsycopg.git

Set up row maker and loaders only once in a server-side cursor lifetime

It wasn't happening once per movement, as I was fearing, but it was happening
exactly twice: once on DECLARE, once on describe_portal(). We actually
don't care about the DECLARE result: it was being set on the cursor only
to detect errors, so now that's done manually.
---

diff --git a/psycopg3/psycopg3/server_cursor.py b/psycopg3/psycopg3/server_cursor.py
index f1386047f..851839ec7 100644
--- a/psycopg3/psycopg3/server_cursor.py
+++ b/psycopg3/psycopg3/server_cursor.py
@@ -61,11 +61,12 @@ class ServerCursorHelper(Generic[ConnectionType]):
 
         yield from cur._start_query(query)
         pgq = cur._convert_query(query, params)
-        cur._execute_send(pgq)
+        cur._execute_send(pgq, no_pqexec=True)
         results = yield from execute(conn.pgconn)
-        cur._execute_results(results)
+        if results[-1].status != pq.ExecStatus.COMMAND_OK:
+            cur._raise_from_results(results)
 
-        # The above result is an COMMAND_OK. Get the cursor result shape
+        # The above result only returned COMMAND_OK. Get the cursor shape
         yield from self._describe_gen(cur)
 
     def _describe_gen(self, cur: BaseCursor[ConnectionType]) -> PQGen[None]:
diff --git a/tests/test_server_cursor.py b/tests/test_server_cursor.py
index 6e908a407..a4e6c0124 100644
--- a/tests/test_server_cursor.py
+++ b/tests/test_server_cursor.py
@@ -151,13 +151,23 @@ def test_nextset(conn):
 
 
 def test_row_factory(conn):
+    n = 0
+
     def my_row_factory(cur):
-        return lambda values: [-v for v in values]
+        nonlocal n
+        n += 1
+        return lambda values: [n] + [-v for v in values]
 
     cur = conn.cursor("foo", row_factory=my_row_factory)
-    cur.execute("select generate_series(1, 3)")
-    r = cur.fetchall()
-    assert r == [[-1], [-2], [-3]]
+    cur.execute("select generate_series(1, 3)", scrollable=True)
+    rows = cur.fetchall()
+    cur.scroll(0, "absolute")
+    while 1:
+        row = cur.fetchone()
+        if not row:
+            break
+        rows.append(row)
+    assert rows == [[1, -1], [1, -2], [1, -3]] * 2
 
 
 def test_rownumber(conn):
diff --git a/tests/test_server_cursor_async.py b/tests/test_server_cursor_async.py
index 5625cd885..191d3dd7f 100644
--- a/tests/test_server_cursor_async.py
+++ b/tests/test_server_cursor_async.py
@@ -153,13 +153,23 @@ async def test_nextset(aconn):
 
 
 async def test_row_factory(aconn):
+    n = 0
+
     def my_row_factory(cur):
-        return lambda values: [-v for v in values]
+        nonlocal n
+        n += 1
+        return lambda values: [n] + [-v for v in values]
 
     cur = aconn.cursor("foo", row_factory=my_row_factory)
-    await cur.execute("select generate_series(1, 3)")
-    r = await cur.fetchall()
-    assert r == [[-1], [-2], [-3]]
+    await cur.execute("select generate_series(1, 3)", scrollable=True)
+    rows = await cur.fetchall()
+    await cur.scroll(0, "absolute")
+    while 1:
+        row = await cur.fetchone()
+        if not row:
+            break
+        rows.append(row)
+    assert rows == [[1, -1], [1, -2], [1, -3]] * 2
 
 
 async def test_rownumber(aconn):