mirror of
https://github.com/hwchase17/langchain.git
synced 2025-09-28 15:00:23 +00:00
0f9b4bf244
**Description:** The current implementation of `DynamoDBChatMessageHistory` updates the `History` attribute for a given chat history record by first extracting the existing contents into memory, appending the new message, and then using the `put_item` method to put the record back. This has the effect of overwriting any additional attributes someone may want to include in the record, like chat session metadata. This PR suggests changing from using `put_item` to using `update_item` instead which will keep any other attributes in the record untouched. The change is backward compatible since 1. `update_item` is an "upsert" operation, creating the record if it doesn't already exist, otherwise updating it 2. It only touches the db insert call and passes the exact same information. The rest of the class is left untouched **Dependencies:** None **Tests and docs:** No unit tests currently exist for the `DynamoDBChatMessageHistory` class. This PR adds the file `libs/community/tests/unit_tests/chat_message_histories/test_dynamodb_chat_message_history.py` to test the `add_message` and `clear` methods. I wanted to use the moto library to mock DynamoDB calls but I could not get poetry to resolve it so I mocked those calls myself in the test. Therefore, no test dependencies were added. The change was tested on a test DynamoDB table as well. The first three images below show the current behavior. First a message is added to chat history, then a value is inserted in the record in some other attribute, and finally another message is added to the record, destroying the other attribute.    The next three images show the new behavior. Once again a value is added to an attribute other than the History attribute, but now when the followup message is added it does not destroy that other attribute. The History attribute itself is unaffected by this change.    The doc located at `docs/docs/integrations/memory/aws_dynamodb.ipynb` required no changes and was tested as well.