langchain_community.chat_message_histories.momento.MomentoChatMessageHistory¶

class langchain_community.chat_message_histories.momento.MomentoChatMessageHistory(session_id: str, cache_client: momento.CacheClient, cache_name: str, *, key_prefix: str = 'message_store:', ttl: Optional[timedelta] = None, ensure_cache_exists: bool = True)[source]¶

Chat message history cache that uses Momento as a backend.

See https://gomomento.com/

Instantiate a chat message history cache that uses Momento as a backend.

Note: to instantiate the cache client passed to MomentoChatMessageHistory, you must have a Momento account at https://gomomento.com/.

Parameters

  • session_id (str) – The session ID to use for this chat session.

  • cache_client (CacheClient) – The Momento cache client.

  • cache_name (str) – The name of the cache to use to store the messages.

  • key_prefix (str, optional) – The prefix to apply to the cache key. Defaults to “message_store:”.

  • ttl (Optional[timedelta], optional) – The TTL to use for the messages. Defaults to None, ie the default TTL of the cache will be used.

  • ensure_cache_exists (bool, optional) – Create the cache if it doesn’t exist. Defaults to True.

Raises

  • ImportError – Momento python package is not installed.

  • TypeError – cache_client is not of type momento.CacheClientObject

Attributes

messages

Retrieve the messages from Momento.

Methods

__init__(session_id, cache_client, cache_name, *)

Instantiate a chat message history cache that uses Momento as a backend.

aadd_messages(messages)

Add a list of messages.

aclear()

Remove all messages from the store

add_ai_message(message)

Convenience method for adding an AI message string to the store.

add_message(message)

Store a message in the cache.

add_messages(messages)

Add a list of messages.

add_user_message(message)

Convenience method for adding a human message string to the store.

aget_messages()

Async version of getting messages.

clear()

Remove the session's messages from the cache.

from_client_params(session_id, cache_name, ...)

Construct cache from CacheClient parameters.
__init__(session_id: str, cache_client: momento.CacheClient, cache_name: str, *, key_prefix: str = 'message_store:', ttl: Optional[timedelta] = None, ensure_cache_exists: bool = True)[source]¶

Instantiate a chat message history cache that uses Momento as a backend.

Note: to instantiate the cache client passed to MomentoChatMessageHistory, you must have a Momento account at https://gomomento.com/.

Parameters

  • session_id (str) – The session ID to use for this chat session.

  • cache_client (CacheClient) – The Momento cache client.

  • cache_name (str) – The name of the cache to use to store the messages.

  • key_prefix (str, optional) – The prefix to apply to the cache key. Defaults to “message_store:”.

  • ttl (Optional[timedelta], optional) – The TTL to use for the messages. Defaults to None, ie the default TTL of the cache will be used.

  • ensure_cache_exists (bool, optional) – Create the cache if it doesn’t exist. Defaults to True.

Raises

  • ImportError – Momento python package is not installed.

  • TypeError – cache_client is not of type momento.CacheClientObject

async aadd_messages(messages: Sequence[BaseMessage]) → None¶

Add a list of messages.

Parameters

messages (Sequence[BaseMessage]) – A list of BaseMessage objects to store.

Return type

None

async aclear() → None¶

Remove all messages from the store

Return type

None

add_ai_message(message: Union[AIMessage, str]) → None¶

Convenience method for adding an AI message string to the store.

Please note that this is a convenience method. Code should favor the bulk add_messages interface instead to save on round-trips to the underlying persistence layer.

This method may be deprecated in a future release.

Parameters

message (Union[AIMessage, str]) – The AI message to add.

Return type

None

add_message(message: BaseMessage) → None[source]¶

Store a message in the cache.

Parameters

message (BaseMessage) – The message object to store.

Raises

  • SdkException – Momento service or network error.

  • Exception – Unexpected response.

Return type

None

add_messages(messages: Sequence[BaseMessage]) → None¶

Add a list of messages.

Implementations should over-ride this method to handle bulk addition of messages in an efficient manner to avoid unnecessary round-trips to the underlying store.

Parameters

messages (Sequence[BaseMessage]) – A list of BaseMessage objects to store.

Return type

None

add_user_message(message: Union[HumanMessage, str]) → None¶

Convenience method for adding a human message string to the store.

Please note that this is a convenience method. Code should favor the bulk add_messages interface instead to save on round-trips to the underlying persistence layer.

This method may be deprecated in a future release.

Parameters

message (Union[HumanMessage, str]) – The human message to add

Return type

None

async aget_messages() → List[BaseMessage]¶

Async version of getting messages.

Can over-ride this method to provide an efficient async implementation.

In general, fetching messages may involve IO to the underlying persistence layer.

Return type

List[BaseMessage]

clear() → None[source]¶

Remove the session’s messages from the cache.

Raises

  • SdkException – Momento service or network error.

  • Exception – Unexpected response.

Return type

None

classmethod from_client_params(session_id: str, cache_name: str, ttl: timedelta, *, configuration: Optional[momento.config.Configuration] = None, api_key: Optional[str] = None, auth_token: Optional[str] = None, **kwargs: Any) → MomentoChatMessageHistory[source]¶

Construct cache from CacheClient parameters.

Parameters

  • session_id (str) –

  • cache_name (str) –

  • ttl (timedelta) –

  • configuration (Optional[momento.config.Configuration]) –

  • api_key (Optional[str]) –

  • auth_token (Optional[str]) –

  • kwargs (Any) –

Return type

MomentoChatMessageHistory

Examples using MomentoChatMessageHistory¶