Add option for MongoDBChatMessageHistory to allow specifying the Session Id field name

[userlerueda]

Checked

• I searched existing ideas and did not find a similar one
• I added a very descriptive title
• I've clearly described the feature request and motivation for it

Feature request

Add an optional keyword argument to MongoDBChatMessageHistory to allow specifying the session_id field name.

Motivation

In our organization, we have a different naming convention for mongodb fields than camelCase. There is not a single answer to using camelCase vs snake_case. The suggestion is to make the library flexible enough to allow this to be changed and not having to hardcode the value without an option to be modified.

Proposal (If applicable)

Change

langchain/libs/partners/mongodb/langchain_mongodb/chat_message_histories.py

Lines 30 to 49 in 9ef1569

	def __init__(
	self,
	connection_string: str,
	session_id: str,
	database_name: str = DEFAULT_DBNAME,
	collection_name: str = DEFAULT_COLLECTION_NAME,
	):
	self.connection_string = connection_string
	self.session_id = session_id
	self.database_name = database_name
	self.collection_name = collection_name
	try:
	self.client: MongoClient = MongoClient(connection_string)
	except errors.ConnectionFailure as error:
	logger.error(error)
	self.db = self.client[database_name]
	self.collection = self.db[collection_name]
	self.collection.create_index("SessionId")

to allow for the value to be passed during initialization. I can submit a PR if this is something that can be accepted.

[userlerueda]

I have submitted a proposal via #22944 that allows this customization