opentelemetry-instrumentation-pymongo: fix invalid mongodb collection attribute type (#3942)

* opentelemetry-instrumentation-pymongo: fix invalid mongodb collection attribute type

* update CHANGELOG.md

CHANGELOG.md

@@ -50,6 +50,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#3904](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3904))
 - build: bump ruff to 0.14.1
   ([#3842](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3842))
+- `opentelemetry-instrumentation-pymongo`: Fix invalid mongodb collection attribute type
+  ([#3942](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3942))
 
 ## Version 1.38.0/0.59b0 (2025-10-16)
 

instrumentation/opentelemetry-instrumentation-pymongo/src/opentelemetry/instrumentation/pymongo/__init__.py

@@ -138,7 +138,7 @@ class CommandTracer(monitoring.CommandListener):
         command_name = event.command_name
         span_name = f"{event.database_name}.{command_name}"
         statement = self._get_statement_by_command_name(command_name, event)
-        collection = event.command.get(event.command_name)
+        collection = _get_command_collection_name(event)
 
         try:
             span = self._tracer.start_span(span_name, kind=SpanKind.CLIENT)
@@ -226,6 +226,13 @@ class CommandTracer(monitoring.CommandListener):
         return statement
 
 
+def _get_command_collection_name(event: CommandEvent) -> str | None:
+    collection_name = event.command.get(event.command_name)
+    if not collection_name or not isinstance(collection_name, str):
+        return None
+    return collection_name
+
+
 def _get_span_dict_key(
     event: CommandEvent,
 ) -> int | tuple[int, tuple[str, int | None]]:

instrumentation/opentelemetry-instrumentation-pymongo/tests/test_pymongo.py

@@ -278,6 +278,43 @@ class TestPymongo(TestBase):
             span.attributes[SpanAttributes.DB_STATEMENT], "aggregate"
         )
 
+    def test_collection_name_attribute(self):
+        scenarios = [
+            (
+                {
+                    "command_name": "find",
+                    "find": "test_collection",
+                },
+                "test_collection",
+            ),
+            ({"command_name": "find"}, None),
+            ({"command_name": "find", "find": b"invalid"}, None),
+        ]
+        for command_attrs, expected in scenarios:
+            with self.subTest(command_attrs=command_attrs, expected=expected):
+                mock_event = MockEvent(command_attrs)
+
+                command_tracer = CommandTracer(
+                    self.tracer, capture_statement=True
+                )
+                command_tracer.started(event=mock_event)
+                command_tracer.succeeded(event=mock_event)
+
+                spans_list = self.memory_exporter.get_finished_spans()
+
+                self.assertEqual(len(spans_list), 1)
+                span = spans_list[0]
+
+                self.assertEqual(
+                    span.attributes[SpanAttributes.DB_STATEMENT], "find"
+                )
+
+                self.assertEqual(
+                    span.attributes.get(SpanAttributes.DB_MONGODB_COLLECTION),
+                    expected,
+                )
+                self.memory_exporter.clear()
+
 
 class MockCommand:
     def __init__(self, command_attrs):