Make Cursor an iterator conforming to DB-API 2.0 (#785)

Author: Copilot

src/MySQLdb/cursors.py

@@ -8,7 +8,6 @@
 
 from ._exceptions import ProgrammingError
 
-
 #: Regular expression for ``Cursor.executemany```.
 #: executemany only supports simple bulk insert.
 #: You can use it to load large dataset.
@@ -329,7 +328,13 @@ def _fetch_row(self, size=1):
         return self._result.fetch_row(size, self._fetch_type)
 
     def __iter__(self):
-        return iter(self.fetchone, None)
+        return self
+
+    def __next__(self):
+        row = self.fetchone()
+        if row is None:
+            raise StopIteration
+        return row
 
     def __getattr__(self, name):
         # DB-API 2.0 optional extension says these errors can be accessed
@@ -419,11 +424,6 @@ def scroll(self, value, mode="relative"):
             raise IndexError("out of range")
         self.rownumber = r
 
-    def __iter__(self):
-        self._check_executed()
-        result = self.rownumber and self._rows[self.rownumber :] or self._rows
-        return iter(result)
-
 
 class CursorUseResultMixIn:
     """This is a MixIn class which causes the result set to be stored
@@ -464,17 +464,6 @@ def fetchall(self):
         self.rownumber = self.rownumber + len(r)
         return r
 
-    def __iter__(self):
-        return self
-
-    def next(self):
-        row = self.fetchone()
-        if row is None:
-            raise StopIteration
-        return row
-
-    __next__ = next
-
 
 class CursorTupleRowsMixIn:
     """This is a MixIn class that causes all rows to be returned as tuples,

tests/test_cursor.py

@@ -284,3 +284,27 @@ def test_sscursor_warning_count():
     rows = cursor.fetchmany(2)
     assert len(rows) == 1
     assert cursor.warning_count == 1
+
+
+@pytest.mark.parametrize("Cursor", [MySQLdb.cursors.Cursor, MySQLdb.cursors.SSCursor])
+def test_cursor_is_iterator(Cursor):
+    conn = connect()
+    cursor = conn.cursor(Cursor)
+
+    cursor.execute("DROP TABLE IF EXISTS test_cursor_is_iterator")
+    cursor.execute(
+        "CREATE TABLE test_cursor_is_iterator (id INT PRIMARY KEY, name VARCHAR(20))"
+    )
+    _tables.append("test_cursor_is_iterator")
+    cursor.executemany(
+        "INSERT INTO test_cursor_is_iterator (id, name) VALUES (%s, %s)",
+        [(1, "a"), (2, "b"), (3, "c")],
+    )
+
+    cursor.execute("SELECT name FROM test_cursor_is_iterator ORDER BY id")
+    assert iter(cursor) is cursor
+    assert next(cursor) == ("a",)
+    assert next(cursor) == ("b",)
+    assert next(cursor) == ("c",)
+    with pytest.raises(StopIteration):
+        next(cursor)