fix(dbapi): add iterable methods to object proxy (backport #4205) (#4281)

This is an automatic backport of pull request #4205 done by [Mergify](https://mergify.com).


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Author: mergify[bot]

ddtrace/contrib/dbapi/__init__.py

@@ -9,6 +9,7 @@
 from ...constants import SPAN_MEASURED_KEY
 from ...ext import SpanTypes
 from ...ext import sql
+from ...internal.compat import PY2
 from ...internal.logger import get_logger
 from ...internal.utils import ArgumentError
 from ...internal.utils import get_argument_value
@@ -47,6 +48,18 @@ def __init__(self, cursor, pin, cfg):
         self._self_last_execute_operation = None
         self._self_config = cfg or config.dbapi2
 
+    def __iter__(self):
+        return self.__wrapped__.__iter__()
+
+    def __next__(self):
+        return self.__wrapped__.__next__()
+
+    if PY2:
+
+        # Python 2 iterators use `next`
+        def next(self):  # noqa: A001
+            return self.__wrapped__.next()
+
     def _trace_method(self, method, name, resource, extra_tags, *args, **kwargs):
         """
         Internal function to trace the call to the underlying cursor method

docs/spelling_wordlist.txt

@@ -94,6 +94,7 @@ initializer
 integration
 integrations
 ip
+iterable
 JSON
 jinja
 js

releasenotes/notes/fix-dbapi-cursor-iter-3e8eb0fbed08e47f.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Add iterable methods on TracedCursor. Previously these were not present and would cause iterable usage of
+    cursors in DB API integrations to fail.

tests/contrib/sqlite3/test_sqlite3.py

@@ -1,5 +1,6 @@
 import sqlite3
 import time
+from typing import TYPE_CHECKING
 
 import pytest
 
@@ -18,6 +19,19 @@
 from tests.utils import assert_is_not_measured
 
 
+if TYPE_CHECKING:
+    from typing import Generator
+
+
+@pytest.fixture
+def patched_conn():
+    # type: () -> Generator[sqlite3.Cursor, None, None]
+    patch()
+    conn = sqlite3.connect(":memory:")
+    yield conn
+    unpatch()
+
+
 class TestSQLite(TracerTestCase):
     def setUp(self):
         super(TestSQLite, self).setUp()
@@ -351,3 +365,9 @@ def test_context_manager(self):
             cursor.fetchall()
             spans = self.get_spans()
             assert len(spans) == 1
+
+
+def test_iterator_usage(patched_conn):
+    """Ensure sqlite3 patched cursors can be used as iterators."""
+    rows = next(patched_conn.execute("select 1"))
+    assert len(rows) == 1