Flowise/packages/components/nodes/memory/MongoDBMemory/MongoDBMemory.ts

import { MongoClient, Collection, Document } from 'mongodb'
import { MongoDBChatMessageHistory } from 'langchain/stores/message/mongodb'
import { BufferMemory, BufferMemoryInput } from 'langchain/memory'
import { mapStoredMessageToChatMessage, AIMessage, HumanMessage, BaseMessage } from 'langchain/schema'
import { convertBaseMessagetoIMessage, getBaseClasses, getCredentialData, getCredentialParam } from '../../../src/utils'
import { FlowiseMemory, ICommonObject, IMessage, INode, INodeData, INodeParams, MemoryMethods, MessageType } from '../../../src/Interface'

let mongoClientSingleton = null

const getMongoClient = async (mongoDBConnectUrl) => {
    if (!mongoClientSingleton) {
        mongoClientSingleton = new MongoClient(mongoDBConnectUrl, { useNewUrlParser: true, useUnifiedTopology: true })
        await mongoClientSingleton.connect()
    }
    return mongoClientSingleton
}

class MongoDB_Memory implements INode {
    label: string
    name: string
    version: number
    description: string
    type: string
    icon: string
    category: string
    baseClasses: string[]
    credential: INodeParams
    inputs: INodeParams[]

    constructor() {
        this.label = 'MongoDB Atlas Chat Memory';
        this.name = 'MongoDBAtlasChatMemory';
        this.version = 1.0;
        this.type = 'MongoDBAtlasChatMemory';
        this.icon = 'mongodb.svg';
        this.category = 'Memory';
        this.description = 'Stores the conversation in MongoDB Atlas';
        this.baseClasses = [this.type, ...getBaseClasses(BufferMemory)];
        this.credential = {
            label: 'Connect Credential',
            name: 'credential',
            type: 'credential',
            credentialNames: ['mongoDBUrlApi']
        };
        this.inputs = [
            {
                label: 'Database',
                name: 'databaseName',
                placeholder: '<DB_NAME>',
                type: 'string'
            },
            {
                label: 'Collection Name',
                name: 'collectionName',
                placeholder: '<COLLECTION_NAME>',
                type: 'string'
            },
            {
                label: 'Session Id',
                name: 'sessionId',
                type: 'string',
                description: 'If not specified, a random id will be used. Learn <a target="_blank" href="https://docs.flowiseai.com/memory/long-term-memory#ui-and-embedded-chat">more</a>',
                default: '',
                additionalParams: true,
                optional: true
            },
            {
                label: 'Memory Key',
                name: 'memoryKey',
                type: 'string',
                default: 'chat_history',
                additionalParams: true
            }
        ];
    }

    async init(nodeData: INodeData, _: string, options: ICommonObject): Promise<any> {
        return initializeMongoDB(nodeData, options);
    }
}

const initializeMongoDB = async (nodeData: INodeData, options: ICommonObject): Promise<BufferMemory> => {
    const databaseName = nodeData.inputs?.databaseName as string;
    const collectionName = nodeData.inputs?.collectionName as string;
    const memoryKey = nodeData.inputs?.memoryKey as string;
    const sessionId = nodeData.inputs?.sessionId as string;

    const credentialData = await getCredentialData(nodeData.credential ?? '', options);
    const mongoDBConnectUrl = getCredentialParam('mongoDBConnectUrl', credentialData, nodeData);

    const client = await getMongoClient(mongoDBConnectUrl);
    const collection = client.db(databaseName).collection(collectionName);

    const mongoDBChatMessageHistory = new MongoDBChatMessageHistory({
        collection,
        sessionId
    });

    mongoDBChatMessageHistory.getMessages = async (): Promise<BaseMessage[]> => {
        const document = await collection.findOne({
            sessionId: (mongoDBChatMessageHistory as any).sessionId
        });
        const messages = document?.messages || [];
        return messages.map(mapStoredMessageToChatMessage);
    };

    mongoDBChatMessageHistory.addMessage = async (message: BaseMessage): Promise<void> => {
        const messages = [message].map((msg) => msg.toDict());
        await collection.updateOne(
            { sessionId: (mongoDBChatMessageHistory as any).sessionId },
            {
                $push: { messages: { $each: messages } }
            },
            { upsert: true }
        );
    };

    mongoDBChatMessageHistory.clear = async (): Promise<void> => {
        await collection.deleteOne({ sessionId: (mongoDBChatMessageHistory as any).sessionId });
    };

    return new BufferMemoryExtended({
        memoryKey: memoryKey ?? 'chat_history',
        chatHistory: mongoDBChatMessageHistory,
        sessionId,
        collection
    });
};

interface BufferMemoryExtendedInput {
    collection: Collection<Document>;
    sessionId: string;
}

class BufferMemoryExtended extends FlowiseMemory implements MemoryMethods {
    sessionId = '';
    collection: Collection<Document>;

    constructor(fields: BufferMemoryInput & BufferMemoryExtendedInput) {
        super(fields);
        this.sessionId = fields.sessionId;
        this.collection = fields.collection;
    }

    async getChatMessages(overrideSessionId = '', returnBaseMessages = false): Promise<IMessage[] | BaseMessage[]> {
        if (!this.collection) return [];

        const id = overrideSessionId ?? this.sessionId;
        const document = await this.collection.findOne({ sessionId: id });
        const messages = document?.messages || [];
        const baseMessages = messages.map(mapStoredMessageToChatMessage);
        return returnBaseMessages ? baseMessages : convertBaseMessagetoIMessage(baseMessages);
    }

    async addChatMessages(msgArray: { text: string; type: MessageType }[], overrideSessionId = ''): Promise<void> {
        if (!this.collection) return;

        const id = overrideSessionId ?? this.sessionId;
        const input = msgArray.find((msg) => msg.type === 'userMessage');
        const output = msgArray.find((msg) => msg.type === 'apiMessage');

        if (input) {
            const newInputMessage = new HumanMessage(input.text);
            const messageToAdd = [newInputMessage].map((msg) => msg.toDict());
            await this.collection.updateOne(
                { sessionId: id },
                {
                    $push: { messages: { $each: messageToAdd } }
                },
                { upsert: true }
            );
        }

        if (output) {
            const newOutputMessage = new AIMessage(output.text);
            const messageToAdd = [newOutputMessage].map((msg) => msg.toDict());
            await this.collection.updateOne(
                { sessionId: id },
                {
                    $push: { messages: { $each: messageToAdd } }
                },
                { upsert: true }
            );
        }
    }

    async clearChatMessages(overrideSessionId = ''): Promise<void> {
        if (!this.collection) return;

        const id = overrideSessionId ?? this.sessionId;
        await this.collection.deleteOne({ sessionId: id });
        await this.clear();
    }
}

module.exports = { nodeClass: MongoDB_Memory };