chat_history

Convert a sequence of messages to strings and concatenate them into one string.

Run a function in an executor.

Message from an AI.

An AIMessage is returned from a chat model as a response to a prompt.

This message represents the output of the model and consists of both the raw output as returned by the model and standardized fields (e.g., tool calls, usage metadata) added by the LangChain framework.

Message from the user.

A HumanMessage is a message that is passed in from a user to the model.

Abstract base class for storing chat message history.

Implementations guidelines:

Implementations are expected to over-ride all or some of the following methods:

• add_messages: sync variant for bulk addition of messages
• aadd_messages: async variant for bulk addition of messages
• messages: sync variant for getting messages
• aget_messages: async variant for getting messages
• clear: sync variant for clearing messages
• aclear: async variant for clearing messages

add_messages contains a default implementation that calls add_message for each message in the sequence. This is provided for backwards compatibility with existing implementations which only had add_message.

Async variants all have default implementations that call the sync variants. Implementers can choose to override the async implementations to provide truly async implementations.

Usage guidelines:

When used for updating history, users should favor usage of add_messages over add_message or other variants like add_user_message and add_ai_message to avoid unnecessary round-trips to the underlying persistence layer.

In memory implementation of chat message history.

Stores messages in a memory list.