Added FalkorDB Chat History Support i.e implemenation, tests, and example notebook

docs/docs/integrations/memory/falkordb_chat_message_history.ipynb

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+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# FalkorDB\n",
+    "\n",
+    "<a href='https://docs.falkordb.com/' target='_blank'>FalkorDB</a> is an open-source graph database management system, renowned for its efficient management of highly connected data. Unlike traditional databases that store data in tables, FalkorDB uses a graph structure with nodes, edges, and properties to represent and store data. This design allows for high-performance queries on complex data relationships.\n",
+    "\n",
+    "This notebook goes over how to use `FalkorDB` to store chat message history\n",
+    "\n",
+    "**NOTE**: You can use FalkorDB locally or use FalkorDB Cloud. <a href='https://docs.falkordb.com/' target='blank'>See installation instructions</a>"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# For this example notebook we will be using FalkorDB locally\n",
+    "host = 'localhost'\n",
+    "port = 6379"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain_community.chat_message_histories import FalkorDBChatMessageHistory\n",
+    "\n",
+    "history = FalkorDBChatMessageHistory(\n",
+    "    host=host,\n",
+    "    port=port,\n",
+    "    session_id=\"session_id_1\"\n",
+    ")\n",
+    "\n",
+    "history.add_user_message(\"hi!\")\n",
+    "\n",
+    "history.add_ai_message(\"whats up?\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "history.messages"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "name": "python",
+   "version": "3.11.7"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}

libs/community/langchain_community/chat_message_histories/falkordb.py

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+from typing import List, Optional, Union
+import os
+import redis.exceptions
+
+from langchain_core.chat_history import BaseChatMessageHistory
+from langchain_core.messages import (
+    AIMessage,
+    BaseMessage,
+    HumanMessage,
+)
+
+from langchain_community.graphs import FalkorDBGraph
+
+
+class FalkorDBChatMessageHistory(BaseChatMessageHistory):
+    """Chat message history stored in a Falkor database.
+
+    This class handles storing and retrieving chat messages in a FalkorDB database.
+    It creates a session and stores messages in a message chain, maintaining a link
+    between subsequent messages.
+
+    Args:
+        session_id (Union[str, int]): The session ID for storing and retrieving messages
+                                also the name of the database.
+        username (Optional[str]): Username for authenticating with FalkorDB.
+        password (Optional[str]): Password for authenticating with FalkorDB.
+        host (str): Host where the FalkorDB is running. Defaults to 'localhost'.
+        port (int): Port number where the FalkorDB is running. Defaults to 6379.
+        node_label (str): Label for the session node in the graph. Defaults to "Session".
+        window (int): The number of messages to retrieve when querying the history. Defaults to 3.
+        ssl (bool): Whether to use SSL for connecting to the database. Defaults to False.
+        graph (Optional[FalkorDBGraph]): Optionally provide an existing FalkorDBGraph object for connecting.
+
+    Example:
+        .. code-block:: python
+            from langchain_community.chat_message_histories import FalkorDBChatMessageHistory
+
+            history = FalkorDBChatMessageHistory(
+                session_id="1234",
+                host="localhost",
+                port=6379,
+            )
+            history.add_message(HumanMessage(content="Hello!"))
+    """
+
+    def __init__(
+        self,
+        session_id: Union[str, int],
+        username: Optional[str] = None,
+        password: Optional[str] = None,
+        host: str = "localhost",
+        port: int = 6379,
+        node_label: str = "Session",
+        window: int = 3,
+        ssl: bool = False,
+        *,
+        graph: Optional[FalkorDBGraph] = None,
+    ) -> None:
+        """Initialize the FalkorDBChatMessageHistory class with the session and connection details."""
+        try:
+            import falkordb
+        except ImportError:
+            raise ImportError(
+                "Could not import falkordb python package."
+                "Please install it with `pip install falkordb`."
+            )
+
+        if not session_id:
+            raise ValueError("Please ensure that the session_id parameter is provided.")
+
+        if graph:
+            self._database = graph._graph
+            self._driver = graph._driver
+        else:
+            self._host = host
+            self._port = port
+            self._username = username or os.environ.get("FALKORDB_USERNAME")
+            self._password = password or os.environ.get("FALKORDB_PASSWORD")
+            self._ssl = ssl
+
+            try:
+                self._driver = falkordb.FalkorDB(
+                    host=self._host,
+                    port=self._port,
+                    username=self._username,
+                    password=self._password,
+                    ssl=self._ssl,
+                )
+            except redis.exceptions.ConnectionError:
+                raise ValueError(
+                    "Could not connect to FalkorDB database. "
+                    "Please ensure that the host and port are correct."
+                )
+            except redis.exceptions.AuthenticationError:
+                raise ValueError(
+                    "Could not connect to FalkorDB database. "
+                    "Please ensure that the username and password are correct."
+                )
+
+        self._database = self._driver.select_graph(session_id)
+        self._session_id = session_id
+        self._node_label = node_label
+        self._window = window
+
+        self._database.query(
+            f"MERGE (s:{self._node_label} {{id:$session_id}})",
+            {"session_id": self._session_id},
+        )
+
+        try:
+            self._database.create_node_vector_index(
+                f"{self._node_label}", "id", dim=5, similarity_function="cosine"
+            )
+        except Exception as e:
+            if "already indexed" in e:
+                raise ValueError(f"{self._node_label} has already been indexed")
+
+    def _process_records(self, records: list) -> list:
+        """Process the records from FalkorDB and convert them into BaseMessage objects.
+
+        Args:
+            records (list): The raw records fetched from the FalkorDB query.
+
+        Returns:
+            list: A list of `BaseMessage` objects.
+        """
+        messages = []
+
+        for record in records:
+            content = record[0].get("data", {}).get("content", "")
+            message_type = record[0].get("type", "").lower()
+
+            if message_type == "human":
+                messages.append(
+                    HumanMessage(
+                        content=content, additional_kwargs={}, response_metadata={}
+                    )
+                )
+            elif message_type == "ai":
+                messages.append(
+                    AIMessage(
+                        content=content, additional_kwargs={}, response_metadata={}
+                    )
+                )
+            else:
+                print(f"Unknown message type: {message_type}")
+
+        return messages
+
+    @property
+    def messages(self) -> List[BaseMessage]:
+        """Retrieve the messages from FalkorDB for the session.
+
+        Returns:
+            List[BaseMessage]: A list of messages in the current session.
+        """
+        query = (
+            f"MATCH (s:{self._node_label})-[:LAST_MESSAGE]->(last_message) "
+            "WHERE s.id = $session_id MATCH p=(last_message)<-[:NEXT*0.."
+            f"{self._window*2}]-() WITH p, length(p) AS length "
+            "ORDER BY length DESC LIMIT 1 UNWIND reverse(nodes(p)) AS node "
+            "RETURN {data:{content: node.content}, type:node.type} AS result"
+        )
+
+        records = self._database.query(
+            query, {"session_id": self._session_id}
+        ).result_set
+
+        messages = self._process_records(records)
+        return messages
+
+    @messages.setter
+    def messages(self, messages: List[BaseMessage]) -> None:
+        """Block direct assignment to 'messages' to prevent misuse."""
+        raise NotImplementedError(
+            "Direct assignment to 'messages' is not allowed."
+            " Use the 'add_message' method instead."
+        )
+
+    def add_message(self, message: BaseMessage) -> None:
+        """Append a message to the session in FalkorDB.
+
+        Args:
+            message (BaseMessage): The message object to add to the session.
+        """
+        create_query = (
+            f"MATCH (s:{self._node_label}) WHERE s.id = $session_id "
+            "CREATE (new:Message {type: $type, content: $content}) "
+            "WITH s, new "
+            "OPTIONAL MATCH (s)-[lm:LAST_MESSAGE]->(last_message:Message) "
+            "FOREACH (_ IN CASE WHEN last_message IS NULL THEN [] ELSE [1] END | "
+            "  MERGE (last_message)-[:NEXT]->(new)) "
+            "MERGE (s)-[:LAST_MESSAGE]->(new) "
+        )
+
+        self._database.query(
+            create_query,
+            {
+                "type": message.type,
+                "content": message.content,
+                "session_id": self._session_id,
+            },
+        )
+
+    def clear(self) -> None:
+        """Clear all messages from the session in FalkorDB.
+
+        Deletes all messages linked to the session and resets the message history.
+
+        Raises:
+            ValueError: If there is an issue with the query or the session.
+        """
+        query = (
+            f"MATCH (s:{self._node_label})-[:LAST_MESSAGE|NEXT*0..]->(m:Message) "
+            "WHERE s.id = $session_id "
+            "WITH m DELETE m"
+        )
+        self._database.query(query, {"session_id": self._session_id})

libs/community/tests/integration_tests/chat_message_histories/test_falkordb_chat_message_history.py

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+"""
+Integration tests for FalkorDB Chat History/Memory functionality.
+
+Note:
+These tests are conducted using a local FalkorDB instance but can also 
+be run against a Cloud FalkorDB instance. Ensure that appropriate host,port
+cusername, and password configurations are set up 
+before running the tests.
+
+Test Cases:
+1. test_add_messages: Test basic functionality of adding and retrieving
+   chat messages from FalkorDB.
+2. test_add_messages_graph_object: Test chat message functionality
+   when passing the FalkorDB driver through a graph object.
+
+"""
+from langchain_core.messages import AIMessage, HumanMessage
+
+from langchain_community.chat_message_histories.falkordb import FalkorDBChatMessageHistory
+from langchain_community.graphs import FalkorDBGraph
+
+def test_add_messages() -> None:
+    """Basic testing: add messages to the FalkorDBChatMessageHistory."""
+    message_store = FalkorDBChatMessageHistory("500daysofSadiya")
+    message_store.clear()
+    assert len(message_store.messages) == 0
+    message_store.add_user_message("Hello! Language Chain!")
+    message_store.add_ai_message("Hi Guys!")
+
+    # create another message store to check if the messages are stored correctly
+    message_store_another = FalkorDBChatMessageHistory("Shebrokemyheart")
+    message_store_another.clear()
+    assert len(message_store_another.messages) == 0
+    message_store_another.add_user_message("Hello! Bot!")
+    message_store_another.add_ai_message("Hi there!")
+    message_store_another.add_user_message("How's this pr going?")
+
+    # Now check if the messages are stored in the database correctly
+    assert len(message_store.messages) == 2
+    assert isinstance(message_store.messages[0], HumanMessage)
+    assert isinstance(message_store.messages[1], AIMessage)
+    assert message_store.messages[0].content == "Hello! Language Chain!"
+    assert message_store.messages[1].content == "Hi Guys!"
+
+    assert len(message_store_another.messages) == 3
+    assert isinstance(message_store_another.messages[0], HumanMessage)
+    assert isinstance(message_store_another.messages[1], AIMessage)
+    assert isinstance(message_store_another.messages[2], HumanMessage)
+    assert message_store_another.messages[0].content == "Hello! Bot!"
+    assert message_store_another.messages[1].content == "Hi there!"
+    assert message_store_another.messages[2].content == "How's this pr going?"
+
+    # Now clear the first history
+    message_store.clear()
+    assert len(message_store.messages) == 0
+    assert len(message_store_another.messages) == 3
+    message_store_another.clear()
+    assert len(message_store.messages) == 0
+    assert len(message_store_another.messages) == 0
+
+
+def test_add_messages_graph_object() -> None:
+    """Basic testing: Passing driver through graph object."""
+    graph = FalkorDBGraph("NeverGonnaLetYouDownNevergonnagiveyouup")
+    message_store = FalkorDBChatMessageHistory(
+        "Gonnahavetoteachmehowtoloveyouagain", graph=graph
+    )
+    message_store.clear()
+    assert len(message_store.messages) == 0
+    message_store.add_user_message("Hello! Language Chain!")
+    message_store.add_ai_message("Hi Guys!")
+    # Now check if the messages are stored in the database correctly
+    assert len(message_store.messages) == 2