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129cd69 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 | import json
import logging
from typing import List
from langchain_core.chat_history import BaseChatMessageHistory
from langchain_core.messages import (
BaseMessage,
message_to_dict,
messages_from_dict,
)
logger = logging.getLogger(__name__)
DEFAULT_CONNECTION_STRING = "postgresql://postgres:mypassword@localhost/chat_history"
class PostgresChatMessageHistory(BaseChatMessageHistory):
"""Chat message history stored in a Postgres database."""
def __init__(
self,
session_id: str,
connection_string: str = DEFAULT_CONNECTION_STRING,
table_name: str = "message_store",
):
import psycopg
from psycopg.rows import dict_row
try:
self.connection = psycopg.connect(connection_string)
self.cursor = self.connection.cursor(row_factory=dict_row)
except psycopg.OperationalError as error:
logger.error(error)
self.session_id = session_id
self.table_name = table_name
self._create_table_if_not_exists()
def _create_table_if_not_exists(self) -> None:
create_table_query = f"""CREATE TABLE IF NOT EXISTS {self.table_name} (
id SERIAL PRIMARY KEY,
session_id TEXT NOT NULL,
message JSONB NOT NULL
);"""
self.cursor.execute(create_table_query)
self.connection.commit()
@property
def messages(self) -> List[BaseMessage]: # type: ignore
"""Retrieve the messages from PostgreSQL"""
query = (
f"SELECT message FROM {self.table_name} WHERE session_id = %s ORDER BY id;"
)
self.cursor.execute(query, (self.session_id,))
items = [record["message"] for record in self.cursor.fetchall()]
messages = messages_from_dict(items)
return messages
def add_message(self, message: BaseMessage) -> None:
"""Append the message to the record in PostgreSQL"""
from psycopg import sql
query = sql.SQL("INSERT INTO {} (session_id, message) VALUES (%s, %s);").format(
sql.Identifier(self.table_name)
)
self.cursor.execute(
query, (self.session_id, json.dumps(message_to_dict(message)))
)
self.connection.commit()
def clear(self) -> None:
"""Clear session memory from PostgreSQL"""
query = f"DELETE FROM {self.table_name} WHERE session_id = %s;"
self.cursor.execute(query, (self.session_id,))
self.connection.commit()
def __del__(self) -> None:
if self.cursor:
self.cursor.close()
if self.connection:
self.connection.close()
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