Customize Server Logic

The MongoDB Chatbot Server provides a few ways to customize the server to meet the needs of your application.

You can add Express.js middleware to validate requests or include custom data in requests.

You can also add custom data to the persisted conversation.

Middleware

You can configure the server to run custom middleware, ConversationsMiddleware. The ConversationsMiddleware include a custom Response.locals object that you can use to access the app's ConversationsService with the conversationsService property and a customData object, where you can store arbitrary data.

Add multiple middleware to the server via the ConversationRouterParams.middleware

Here's a basic middleware and how you can add it to the server.

import { ConversationsMiddleware, AppConfig } from "mongodb-chatbot-server";

const someMiddleware: ConversationsMiddleware = async (req, res, next) => {
  try {
    const conversation = await res.locals.conversations.findById(
      req.params.conversationId
    );
    // ...do something with the conversation

    // Add custom data to the response
    res.locals.customData = {
      foo: "bar",
    };
  } catch (err) {
    next(err);
  } finally {
    next();
  }
};

const appConfig: AppConfig = {
  // ...other config
  conversationsRouterParams: {
    middleware: [someMiddleware],
    // ...other config
  },
};
// ...create app

Request Validation

You can use custom middleware to validate the request before it's processed by the /conversations routes.

import { ConversationsMiddleware } from "mongodb-chatbot-server";

const requireUserId: ConversationsMiddleware = async (req, res, next) => {
  const userId = req.headers.userId;
  if (!userId) {
    return res.status(400).json({
      error: "Missing userId header",
    });
  }
  next();
};

Include Custom Data to be Processed by the Server

You can also use the middleware to modify the request or response objects. For example, you could store additional data in the Response.locals object or perform user authentication.

import { ConversationsMiddleware } from "mongodb-chatbot-server";
import { authenticateUser } from "./auth"; // Some authentication function

const authenticateUser: ConversationsMiddleware = async (req, res, next) => {
  try {
    const token = req.headers.authToken;
    if (!token) {
      return res.status(400).json({
        error: "Missing authToken header",
      });
    }
    // Authenticate user
    const user = await authenticateUser(token);
    if (!user) {
      return res.status(401).json({
        error: "Invalid authToken",
      });
    }
    // Add authenticated user data to the response
    res.locals.customData = {
      user,
    };
    next();
  } catch (err) {
    next(err);
  }
};

Included Middleware

The MongoDB Chatbot Server includes the following middleware.

• requireRequestOrigin(): Requires that the request includes a X-Request-Origin or origin header. Enabled by default.
• requireValidIpAddress(): Requires that the request includes a X-Forwarded-For header with a valid IP address. Enabled by default.

Add Custom Data

You can add custom data to the persisted conversation or to individual messages.

AddCustomDataFunc

Add custom data using a AddCustomDataFunc function.

The function accepts the Express Request and Response. The Response includes the ConversationsRouterLocals in the Response.locals property. The function returns a Promise that resolves to a ConversationCustomData object.

import { AddCustomDataFunc } from "mongodb-chatbot-server";

const addOriginAndIpToCustomData: AddCustomDataFunc = async (req, res) =>
  res.locals.customData.origin
    ? { origin: res.locals.customData.origin, ip: req.ip }
    : undefined;

Add Custom Data to Conversation

You can add custom data to the Conversation.customData property persisted in the database.

To add custom data to the conversation, set the ConversationsRouterParams.createConversationCustomData to a CustomDataFunc. This function is run when you create a conversation with the POST /conversations endpoint.

import { AddCustomData, AppConfig } from "mongodb-chatbot-server";

const addOriginAndIpToCustomData: AddCustomDataFunc = async (req, res) =>
  res.locals.customData.origin
    ? { origin: res.locals.customData.origin, ip: req.ip }
    : undefined;

const appConfig: AppConfig = {
  // ...other config
  conversationsRouterParams: {
    createConversationCustomData: addOriginAndIpToCustomData,
    // ...other config
  },
};
// ...create app

This creates a Conversation in the database with the following schema:

{
  _id: ObjectId("Some ObjectId"),
  messages: [ /*...*/ ],
  createdAt: Date("Some Date"),
  customData: {
    origin: "https://example.com";
    ip: "192.158.1.38";
  }
}

Add Custom Data to Messages

You can add custom data to the Conversation.messages[].customData property persisted in the database.

To add custom data to the conversation, set the ConversationsRouterParams.addMessageToConversationCustomData to a CustomDataFunc. This function is run when you create a conversation with the POST /conversations/:conversationId/messages endpoint.

import { AddCustomData, AppConfig } from "mongodb-chatbot-server";

const addOriginAndIpToCustomData: AddCustomDataFunc = async (req, res) =>
  res.locals.customData.origin
    ? { origin: res.locals.customData.origin, ip: req.ip }
    : undefined;

const appConfig: AppConfig = {
  // ...other config
  conversationsRouterParams: {
    addMessageToConversationCustomData: addOriginAndIpToCustomData,
    // ...other config
  },
};
// ...create app

This creates a Conversation in the database with the following schema:

{
  _id: ObjectId("Some ObjectId"),
  createdAt: Date("Some Date"),
  messages: [ /*...other messages*/,
    {
      _id: ObjectId("Some ObjectId"),
      role: "user",
      content: "Some message",
      createdAt: Date("Some Date"),
      customData: {
        origin: "https://example.com",
        ip: "192.158.1.38",
      }
    },
    {/*...assistant message*/}],
}

Included Custom Data Functions

By default, the MongoDB Chatbot Server includes custom data functions that add the following custom data:

• Conversation.customData: origin and ip from the request.
• For all user messages, Message.customData: origin and from the request.