anthropic[patch]: be robust to null fields when translating usage metadata (#31151)

libs/partners/anthropic/langchain_anthropic/chat_models.py

@@ -1844,11 +1844,11 @@ def _create_usage_metadata(anthropic_usage: BaseModel) -> UsageMetadata:
 
     # Anthropic input_tokens exclude cached token counts.
     input_tokens = (
-        getattr(anthropic_usage, "input_tokens", 0)
+        (getattr(anthropic_usage, "input_tokens", 0) or 0)
         + (input_token_details["cache_read"] or 0)
         + (input_token_details["cache_creation"] or 0)
     )
-    output_tokens = getattr(anthropic_usage, "output_tokens", 0)
+    output_tokens = getattr(anthropic_usage, "output_tokens", 0) or 0
     return UsageMetadata(
         input_tokens=input_tokens,
         output_tokens=output_tokens,

libs/partners/anthropic/tests/unit_tests/test_chat_models.py

@@ -1,7 +1,7 @@
 """Test chat model integration."""
 
 import os
-from typing import Any, Callable, Literal, cast
+from typing import Any, Callable, Literal, Optional, cast
 from unittest.mock import patch
 
 import anthropic
@@ -15,6 +15,7 @@ from pytest import CaptureFixture, MonkeyPatch
 
 from langchain_anthropic import ChatAnthropic
 from langchain_anthropic.chat_models import (
+    _create_usage_metadata,
     _format_image,
     _format_messages,
     _merge_messages,
@@ -954,3 +955,42 @@ def test_get_num_tokens_from_messages_passes_kwargs() -> None:
     assert (
         _Client.return_value.beta.messages.count_tokens.call_args.kwargs["foo"] == "bar"
     )
+
+
+def test_usage_metadata_standardization() -> None:
+    class UsageModel(BaseModel):
+        input_tokens: int = 10
+        output_tokens: int = 5
+        cache_read_input_tokens: int = 3
+        cache_creation_input_tokens: int = 2
+
+    # Happy path
+    usage = UsageModel()
+    result = _create_usage_metadata(usage)
+    assert result["input_tokens"] == 15  # 10 + 3 + 2
+    assert result["output_tokens"] == 5
+    assert result["total_tokens"] == 20
+    assert result["input_token_details"] == {"cache_read": 3, "cache_creation": 2}
+
+    # Null input and output tokens
+    class UsageModelNulls(BaseModel):
+        input_tokens: Optional[int] = None
+        output_tokens: Optional[int] = None
+        cache_read_input_tokens: Optional[int] = None
+        cache_creation_input_tokens: Optional[int] = None
+
+    usage_nulls = UsageModelNulls()
+    result = _create_usage_metadata(usage_nulls)
+    assert result["input_tokens"] == 0
+    assert result["output_tokens"] == 0
+    assert result["total_tokens"] == 0
+
+    # Test missing fields
+    class UsageModelMissing(BaseModel):
+        pass
+
+    usage_missing = UsageModelMissing()
+    result = _create_usage_metadata(usage_missing)
+    assert result["input_tokens"] == 0
+    assert result["output_tokens"] == 0
+    assert result["total_tokens"] == 0