From 763ef9262ceedaa0e80bc1fc2947ea12386688de Mon Sep 17 00:00:00 2001
From: Brace Sproul <braceasproul@gmail.com>
Date: Thu, 10 Oct 2024 18:23:43 -0700
Subject: [PATCH] fix(openai): Ensure usage_metadata is serialized when
 invoking (#6966)

---
 libs/langchain-openai/src/chat_models.ts | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libs/langchain-openai/src/chat_models.ts b/libs/langchain-openai/src/chat_models.ts
index 93a3dbd30e45..728d08eabed0 100644
--- a/libs/langchain-openai/src/chat_models.ts
+++ b/libs/langchain-openai/src/chat_models.ts
@@ -1506,6 +1506,11 @@ export class ChatOpenAI<
         if (isAIMessage(generation.message)) {
           generation.message.usage_metadata = usageMetadata;
         }
+        // Fields are not serialized unless passed to the constructor
+        // Doing this ensures all fields on the message are serialized
+        generation.message = new AIMessage({
+          ...generation.message,
+        });
         generations.push(generation);
       }
       return {