Memory, base class¶

This implements the Cassandra-specific I/O facilities, and is then used by LangChain to power every other, more sophisticated, abstraction around keeping chat memory.

In [1]:

from langchain.memory import CassandraChatMessageHistory

from langchain.memory import CassandraChatMessageHistory

A database connection is needed. (If on a Colab, the only supported option is the cloud service Astra DB.)

In [2]:

# Ensure loading of database credentials into environment variables:
import os
from dotenv import load_dotenv
load_dotenv("../../../.env")

import cassio

# Ensure loading of database credentials into environment variables: import os from dotenv import load_dotenv load_dotenv("../../../.env") import cassio

Select your choice of database by editing this cell, if needed:

In [3]:

database_mode = "cassandra"  # "cassandra" / "astra_db"

database_mode = "cassandra" # "cassandra" / "astra_db"

In [4]:

if database_mode == "astra_db":
    cassio.init(
        database_id=os.environ["ASTRA_DB_ID"],
        token=os.environ["ASTRA_DB_APPLICATION_TOKEN"],
        keyspace=os.environ.get("ASTRA_DB_KEYSPACE"),  # this is optional
    )

if database_mode == "astra_db": cassio.init( database_id=os.environ["ASTRA_DB_ID"], token=os.environ["ASTRA_DB_APPLICATION_TOKEN"], keyspace=os.environ.get("ASTRA_DB_KEYSPACE"), # this is optional )

In [5]:

if database_mode == "cassandra":
    from cqlsession import getCassandraCQLSession, getCassandraCQLKeyspace
    cassio.init(
        session=getCassandraCQLSession(),
        keyspace=getCassandraCQLKeyspace(),
    )

if database_mode == "cassandra": from cqlsession import getCassandraCQLSession, getCassandraCQLKeyspace cassio.init( session=getCassandraCQLSession(), keyspace=getCassandraCQLKeyspace(), )

Create the ChatMessageHistory¶

In [6]:

message_history = CassandraChatMessageHistory(
    session_id='test-session',
    session=None,
    keyspace=None,
    ttl_seconds = 3600,
)
message_history.clear()

message_history = CassandraChatMessageHistory( session_id='test-session', session=None, keyspace=None, ttl_seconds = 3600, ) message_history.clear()

The memory starts empty:

In [7]:

message_history.messages

message_history.messages

Out[7]:

[]

Insert and retrieve chat messages¶

In [8]:

message_history.add_user_message('Hello, I am human.')

message_history.add_user_message('Hello, I am human.')

In [9]:

message_history.add_ai_message('Hello, I am the bot.')

message_history.add_ai_message('Hello, I am the bot.')

In [10]:

message_history.messages

message_history.messages

Out[10]:

[HumanMessage(content='Hello, I am human.', additional_kwargs={}, example=False),
 AIMessage(content='Hello, I am the bot.', additional_kwargs={}, example=False)]

In [11]:

message_history.clear()

message_history.clear()

In [12]:

message_history.messages

message_history.messages

Out[12]:

[]