16_b_CREATING_A_MONGODB_STORE_ADAPTER.md

Building Out the MongoDB Store Adapter for Your Hyv Project

Overview

Having outlined our MongoDB store adapter class, the next stage involves the implementation of set and get methods, as mandated by the StoreAdapter interface. This guide will direct you through this process.

Prerequisites

In addition to the prerequisites from the first part, you will need a running MongoDB database that the MongoDB store adapter can interact with.

Guide

Implementing the Set Method

The set method is used for storing messages. It accepts a message as a parameter, generates a unique ID for it using nanoid, and then preserves the message in the MongoDB database via the MessageModel.

class MongoDBStoreAdapter {
    /**
     * Stores a message in MongoDB and returns the messageId.
     * @async
     * @template Message - A type that extends ModelMessage.
     * @param message - The message to store.
     * @returns - A Promise that resolves to the messageId.
     */
    async set<Message extends ModelMessage>(message: Message): Promise<string> {
        const messageId = nanoid();
        await new MessageModel({ _id: messageId, message }).save();

        return messageId;
    }
}

Implementing the Get Method

Subsequently, the get method is defined for retrieving messages. It takes a message ID as an input, fetches the corresponding message from the MongoDB database using MessageModel, and then returns the message.

class MongoDBStoreAdapter {
    /**
     * Retrieves a message by messageId from MongoDB.
     * @async
     * @param messageId - The messageId of the message to retrieve.
     * @returns - A Promise that resolves to the message.
     * @throws - If there is an error retrieving the message.
     */
    async get(messageId: string): Promise<ModelMessage> {
        const doc = await MessageModel.findById(messageId);
        if (doc) {
            return doc.message;
        }

        throw new Error(`Error retrieving message with ID ${messageId}`);
    }
}

If no message matching the provided ID is found, the method will throw an error.

Connecting to MongoDB

Before employing the MongoDBStoreAdapter, it is essential to establish a connection to your MongoDB database using Mongoose. This can be done in your main application file:

mongoose.connect("mongodb://localhost:27017/mydb", {
    useNewUrlParser: true,
    useUnifiedTopology: true,
});

Make sure to replace 'mongodb://localhost:27017/mydb' with your MongoDB database's connection string.

Following successful connection, the MongoDBStoreAdapter can now be used as a store for an Agent within Hyv:

import { Agent } from "@hyv/core";
import { GPTModelAdapter } from "@hyv/openai";
import { MongoDBStoreAdapter } from "./MongoDBStoreAdapter";

const store = new MongoDBStoreAdapter();
const agent = new Agent(new GPTModelAdapter(), { store });

// Now you can use the agent to assign and retrieve messages...

Summary

This guide led you through the process of building out the MongoDB store adapter for your Hyv project. We implemented the set and get methods, connected to MongoDB, and incorporated the adapter into a Hyv Agent. This tutorial demonstrated the process for MongoDB; however, you can apply a similar approach to establish store adapters for any other database or storage system. Simply implement the StoreAdapter interface according to your specific database or storage system's requirements.

Tags

Hyv, StoreAdapter, MongoDB, Mongoose, nanoid, ModelMessage, Node.js, npm, Agent, GPTModelAdapter