BaseChatMessageHistory#
- class langchain_core.chat_history.BaseChatMessageHistory[source]#
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 over-ride 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.
Example: Shows a default implementation.
class FileChatMessageHistory(BaseChatMessageHistory): storage_path: str session_id: str @property def messages(self): with open(os.path.join(storage_path, session_id), 'r:utf-8') as f: messages = json.loads(f.read()) return messages_from_dict(messages) def add_messages(self, messages: Sequence[BaseMessage]) -> None: all_messages = list(self.messages) # Existing messages all_messages.extend(messages) # Add new messages serialized = [message_to_dict(message) for message in all_messages] # Can be further optimized by only writing new messages # using append mode. with open(os.path.join(storage_path, session_id), 'w') as f: json.dump(f, messages) def clear(self): with open(os.path.join(storage_path, session_id), 'w') as f: f.write("[]")
Attributes
Methods
__init__
()aadd_messages
(messages)Async add a list of messages.
aclear
()Async remove all messages from the store
add_ai_message
(message)Convenience method for adding an AI message string to the store.
add_message
(message)Add a Message object to the store.
add_messages
(messages)Add a list of messages.
add_user_message
(message)Convenience method for adding a human message string to the store.
Async version of getting messages.
clear
()Remove all messages from the store
- __init__()#
- async aadd_messages(messages: Sequence[BaseMessage]) None [source]#
Async add a list of messages.
- Parameters:
messages (Sequence[BaseMessage]) – A sequence of BaseMessage objects to store.
- Return type:
None
- add_ai_message(message: AIMessage | str) None [source]#
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 (AIMessage | str) – The AI message to add.
- Return type:
None
- add_message(message: BaseMessage) None [source]#
Add a Message object to the store.
- Parameters:
message (BaseMessage) – A BaseMessage object to store.
- Raises:
NotImplementedError – If the sub-class has not implemented an efficient add_messages method.
- Return type:
None
- add_messages(messages: Sequence[BaseMessage]) None [source]#
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 sequence of BaseMessage objects to store.
- Return type:
None
- add_user_message(message: HumanMessage | str) None [source]#
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 (HumanMessage | str) – The human message to add to the store.
- Return type:
None
- async aget_messages() List[BaseMessage] [source]#
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]
Examples using BaseChatMessageHistory