fix(utils): Avoid double serialization of strings in safe_serialize

ericapisani · claude · ericapisani · commit 5937e9c401a1 · 2026-03-04T14:23:01.000-05:00
When serialize_item() already returns a string (for plain strings,
callables, or objects with __dict__), skip json.dumps to prevent
wrapping the value in extra quotes with escaped characters.

Co-Authored-By: Claude &lt;noreply@anthropic.com&gt;
diff --git a/sentry_sdk/utils.py b/sentry_sdk/utils.py
@@ -2005,7 +2005,11 @@ def serialize_item(
 
     try:
         serialized = serialize_item(data)
-        return json.dumps(serialized, default=str)
+        return (
+            json.dumps(serialized, default=str)
+            if not isinstance(serialized, str)
+            else serialized
+        )
     except Exception:
         return str(data)
 
diff --git a/tests/test_utils.py b/tests/test_utils.py
@@ -35,6 +35,7 @@
     exc_info_from_error,
     get_lines_from_file,
     package_version,
+    safe_serialize,
 )
 
 
@@ -1062,5 +1063,36 @@ def fake_getlines(filename):
         assert result == expected_result
 
 
+def test_safe_serialize_plain_string():
+    assert safe_serialize("already a string") == "already a string"
+
+
+def test_safe_serialize_json_string():
+    assert safe_serialize('{"key": "value"}') == '{"key": "value"}'
+
+
+def test_safe_serialize_dict():
+    assert safe_serialize({"key": "value"}) == '{"key": "value"}'
+
+
+def test_safe_serialize_callable():
+    def my_func():
+        pass
+
+    result = safe_serialize(my_func)
+    assert result.startswith("<function")
+    assert '"' not in result[:1]  # no wrapping quotes from json.dumps
+
+
+def test_safe_serialize_object():
+    class MyClass:
+        def __init__(self):
+            self.x = 1
+
+    result = safe_serialize(MyClass())
+    assert result.startswith("<MyClass")
+    assert '"' not in result[:1]  # no wrapping quotes from json.dumps
+
+
 def test_package_version_is_none():
     assert package_version("non_existent_package") is None
