fix(dbapi): executemany() hiding all the results except the last (#181)

Author: Ilya Gurov

google/cloud/spanner_dbapi/cursor.py

@@ -37,6 +37,7 @@
 from google.cloud.spanner_dbapi.parse_utils import get_param_types
 from google.cloud.spanner_dbapi.parse_utils import sql_pyformat_args_to_spanner
 from google.cloud.spanner_dbapi.utils import PeekIterator
+from google.cloud.spanner_dbapi.utils import StreamedManyResultSets
 
 _UNSET_COUNT = -1
 
@@ -210,8 +211,20 @@ def executemany(self, operation, seq_of_params):
         """
         self._raise_if_closed()
 
+        classification = parse_utils.classify_stmt(operation)
+        if classification == parse_utils.STMT_DDL:
+            raise ProgrammingError(
+                "Executing DDL statements with executemany() method is not allowed."
+            )
+
+        many_result_set = StreamedManyResultSets()
+
         for params in seq_of_params:
             self.execute(operation, params)
+            many_result_set.add_iter(self._itr)
+
+        self._result_set = many_result_set
+        self._itr = many_result_set
 
     def fetchone(self):
         """Fetch the next row of a query result set, returning a single

google/cloud/spanner_dbapi/utils.py

@@ -14,6 +14,8 @@
 
 import re
 
+re_UNICODE_POINTS = re.compile(r"([^\s]*[\u0080-\uFFFF]+[^\s]*)")
+
 
 class PeekIterator:
     """
@@ -55,7 +57,43 @@ def __iter__(self):
         return self
 
 
-re_UNICODE_POINTS = re.compile(r"([^\s]*[\u0080-\uFFFF]+[^\s]*)")
+class StreamedManyResultSets:
+    """Iterator to walk through several `StreamedResultsSet` iterators.
+    This type of iterator is used by `Cursor.executemany()`
+    method to iterate through several `StreamedResultsSet`
+    iterators like they all are merged into single iterator.
+    """
+
+    def __init__(self):
+        self._iterators = []
+        self._index = 0
+
+    def add_iter(self, iterator):
+        """Add new iterator into this one.
+        :type iterator: :class:`google.cloud.spanner_v1.streamed.StreamedResultSet`
+        :param iterator: Iterator to merge into this one.
+        """
+        self._iterators.append(iterator)
+
+    def __next__(self):
+        """Return the next value from the currently streamed iterator.
+        If the current iterator is streamed to the end,
+        start to stream the next one.
+        :rtype: list
+        :returns: The next result row.
+        """
+        try:
+            res = next(self._iterators[self._index])
+        except StopIteration:
+            self._index += 1
+            res = self.__next__()
+        except IndexError:
+            raise StopIteration
+
+        return res
+
+    def __iter__(self):
+        return self
 
 
 def backtick_unicode(sql):

tests/system/test_system_dbapi.py

@@ -305,6 +305,46 @@ def test_results_checksum(self):
 
         self.assertEqual(cursor._checksum.checksum.digest(), checksum.digest())
 
+    def test_execute_many(self):
+        # connect to the test database
+        conn = Connection(Config.INSTANCE, self._db)
+        cursor = conn.cursor()
+
+        cursor.execute(
+            """
+INSERT INTO contacts (contact_id, first_name, last_name, email)
+VALUES (1, 'first-name', 'last-name', 'test.email@example.com'),
+       (2, 'first-name2', 'last-name2', 'test.email2@example.com')
+        """
+        )
+        conn.commit()
+
+        cursor.executemany(
+            """
+SELECT * FROM contacts WHERE contact_id = @a1
+""",
+            ({"a1": 1}, {"a1": 2}),
+        )
+        res = cursor.fetchall()
+        conn.commit()
+
+        self.assertEqual(len(res), 2)
+        self.assertEqual(res[0][0], 1)
+        self.assertEqual(res[1][0], 2)
+
+        # checking that execute() and executemany()
+        # results are not mixed together
+        cursor.execute(
+            """
+SELECT * FROM contacts WHERE contact_id = 1
+""",
+        )
+        res = cursor.fetchone()
+        conn.commit()
+
+        self.assertEqual(res[0], 1)
+        conn.close()
+
 
 def clear_table(transaction):
     """Clear the test table."""

tests/unit/spanner_dbapi/test_cursor.py

@@ -257,6 +257,22 @@ def test_executemany_on_closed_cursor(self):
         with self.assertRaises(InterfaceError):
             cursor.executemany("""SELECT * FROM table1 WHERE "col1" = @a1""", ())
 
+    def test_executemany_DLL(self):
+        from google.cloud.spanner_dbapi import connect, ProgrammingError
+
+        with mock.patch(
+            "google.cloud.spanner_v1.instance.Instance.exists", return_value=True,
+        ):
+            with mock.patch(
+                "google.cloud.spanner_v1.database.Database.exists", return_value=True,
+            ):
+                connection = connect("test-instance", "test-database")
+
+        cursor = connection.cursor()
+
+        with self.assertRaises(ProgrammingError):
+            cursor.executemany("""DROP DATABASE database_name""", ())
+
     def test_executemany(self):
         from google.cloud.spanner_dbapi import connect
 
@@ -272,6 +288,9 @@ def test_executemany(self):
                 connection = connect("test-instance", "test-database")
 
         cursor = connection.cursor()
+        cursor._result_set = [1, 2, 3]
+        cursor._itr = iter([1, 2, 3])
+
         with mock.patch(
             "google.cloud.spanner_dbapi.cursor.Cursor.execute"
         ) as execute_mock: