Fix multiple calls of getresult() after send_query()

docs/contents/changelog.rst

@@ -13,6 +13,7 @@ Version 5.2.5 (to be released)
     - generated columns can be requested with the `get_generated()` method
     - generated columns are ignored by the insert, update and upsert method
 - Avoid internal query and error when casting the `sql_identifier` type (#82)
+- Fix issue with multiple calls of `getresult()` after `send_query()` (#80)
 
 Version 5.2.4 (2022-03-26)
 --------------------------

pgquery.c

@@ -139,8 +139,9 @@ _get_async_result(queryObject *self, int keep) {
         Py_END_ALLOW_THREADS
         if (!self->result) {
             /* end of result set, return None */
-            Py_DECREF(self->pgcnx);
-            self->pgcnx = NULL;
+            self->max_row = 0;
+            self->num_fields = 0;
+            self->col_types = NULL;
             Py_INCREF(Py_None);
             return Py_None;
         }
@@ -161,7 +162,7 @@ _get_async_result(queryObject *self, int keep) {
                 }
             }
             else if (result == Py_None) {
-                /* It's would be confusing to return None here because the
+                /* It would be confusing to return None here because the
                    caller has to call again until we return None. We can't
                    just consume that final None because we don't know if there
                    are additional statements following this one, so we return
@@ -180,7 +181,12 @@ _get_async_result(queryObject *self, int keep) {
             Py_DECREF(self);
             return NULL;
         }
+    } else if (self->async == 2 &&
+               !self->max_row && !self->num_fields && !self->col_types) {
+        Py_INCREF(Py_None);
+        return Py_None;
     }
+
     /* return the query object itself as sentinel for a normal query result */
     return (PyObject *)self;
 }
@@ -722,7 +728,6 @@ query_namedresult(queryObject *self, PyObject *noargs)
     }
 
     if ((res_list = _get_async_result(self, 1)) == (PyObject *)self) {
-
         res = PyObject_CallFunction(namediter, "(O)", self);
         if (!res) return NULL;
         if (PyList_Check(res)) return res;

tests/test_classic_connection.py

@@ -580,6 +580,17 @@ def testNamedresultAsync(self):
         self.assertEqual(v._fields, ('alias0',))
         self.assertEqual(v.alias0, 0)
         self.assertIsNone(query.namedresult())
+        self.assertIsNone(query.namedresult())
+
+    def testListFieldsAfterSecondGetResultAsync(self):
+        q = "select 1 as one"
+        query = self.c.send_query(q)
+        self.assertEqual(query.getresult(), [(1,)])
+        self.assertEqual(query.listfields(), ('one',))
+        self.assertIsNone(query.getresult())
+        self.assertEqual(query.listfields(), ())
+        self.assertIsNone(query.getresult())
+        self.assertEqual(query.listfields(), ())
 
     def testGet3Cols(self):
         q = "select 1,2,3"

tests/test_classic_dbwrapper.py

@@ -158,6 +158,23 @@ def testDeleteDb(self):
         self.assertRaises(pg.InternalError, db.close)
         del db
 
+    def testAsyncQueryBeforeDeletion(self):
+        db = DB()
+        query = db.send_query('select 1')
+        self.assertEqual(query.getresult(), [(1,)])
+        self.assertIsNone(query.getresult())
+        self.assertIsNone(query.getresult())
+        del db
+        gc.collect()
+
+    def testAsyncQueryAfterDeletion(self):
+        db = DB()
+        query = db.send_query('select 1')
+        del db
+        gc.collect()
+        self.assertIsNone(query.getresult())
+        self.assertIsNone(query.getresult())
+
 
 class TestDBClassBasic(unittest.TestCase):
     """Test existence of the DB class wrapped pg connection methods."""