From 8c35da51a4cd2898dde207c5f48f0f605d4a1251 Mon Sep 17 00:00:00 2001
From: Rodolfo Carvalho <rodolfo.carvalho@sentry.io>
Date: Fri, 26 Jun 2020 11:59:53 +0200
Subject: [PATCH] feat: Access transaction in current scope (#734)

Specially when trying to add spans to automatically instrumented
transactions, users need access to the current transaction.

This gives direct access no matter how deep the code is in the
transaction/span tree.
---
 sentry_sdk/scope.py   | 27 +++++++++++++++++++++++++--
 tests/test_tracing.py | 16 +++++++++++++++-
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/sentry_sdk/scope.py b/sentry_sdk/scope.py
index c721b56505..e5478cebc9 100644
--- a/sentry_sdk/scope.py
+++ b/sentry_sdk/scope.py
@@ -134,10 +134,33 @@ def fingerprint(self, value):
         """When set this overrides the default fingerprint."""
         self._fingerprint = value
 
-    @_attr_setter
+    @property
+    def transaction(self):
+        # type: () -> Any
+        # would be type: () -> Optional[Span], see https://github.com/python/mypy/issues/3004
+        # XXX: update return type to Optional[Transaction]
+        """Return the transaction (root span) in the scope."""
+        if self._span is None or self._span._span_recorder is None:
+            return None
+        try:
+            return self._span._span_recorder.spans[0]
+        except (AttributeError, IndexError):
+            return None
+
+    @transaction.setter
     def transaction(self, value):
-        # type: (Optional[str]) -> None
+        # type: (Any) -> None
+        # would be type: (Optional[str]) -> None, see https://github.com/python/mypy/issues/3004
         """When set this forces a specific transaction name to be set."""
+        # XXX: the docstring above is misleading. The implementation of
+        # apply_to_event prefers an existing value of event.transaction over
+        # anything set in the scope.
+        # XXX: note that with the introduction of the Scope.transaction getter,
+        # there is a semantic and type mismatch between getter and setter. The
+        # getter returns a transaction, the setter sets a transaction name.
+        # Without breaking version compatibility, we could make the setter set a
+        # transaction name or transaction (self._span) depending on the type of
+        # the value argument.
         self._transaction = value
         span = self._span
         if span:
diff --git a/tests/test_tracing.py b/tests/test_tracing.py
index af479ee90d..d49eeaf826 100644
--- a/tests/test_tracing.py
+++ b/tests/test_tracing.py
@@ -3,7 +3,7 @@
 
 import pytest
 
-from sentry_sdk import Hub, capture_message
+from sentry_sdk import Hub, capture_message, start_span
 from sentry_sdk.tracing import Span
 
 
@@ -181,3 +181,17 @@ def before_send(event, hint):
         pass
 
     assert len(events) == 1
+
+
+def test_get_transaction_from_scope(sentry_init, capture_events):
+    sentry_init(traces_sample_rate=1.0)
+    events = capture_events()
+
+    with start_span(transaction="/"):
+        with start_span(op="child-span"):
+            with start_span(op="child-child-span"):
+                scope = Hub.current.scope
+                assert scope.span.op == "child-child-span"
+                assert scope.transaction.transaction == "/"
+
+    assert len(events) == 1