Working on HIMS SaaS using MEAN stack

Question

I was facing an issue with changing models on the fly — since we don’t just need isolation based on string or ID, but also data-level differences for each HIMS instance. To handle this, I created a simple library. Could you help me verify if this approach will work, and point out any potential issues I might face with aggregation? I’m already aware that aggregation can't be performed between two different databases.

// utils/TenantConnectionManager.js
import mongoose from "mongoose";
class TenantConnectionManager {
 constructor() {
 this.connections = {}; // { apiKey: { conn, timer } }
 this.TIMEOUT = 60 * 60 * 1000; // 1 hour
 }
 /**
 * Get or create a tenant connection
 */
 async getConnection(apiKey, dbURI) {
 if (this.connections[apiKey]) {
 // Reset timeout
 clearTimeout(this.connections[apiKey].timer);
 this.connections[apiKey].timer = setTimeout(() => {
 this.disconnect(apiKey);
 }, this.TIMEOUT);
 return this.connections[apiKey].conn;
 }
 // Create fresh connection
 const conn = await mongoose.createConnection(dbURI, {
 useNewUrlParser: true,
 useUnifiedTopology: true,
 });
 const timer = setTimeout(() => {
 this.disconnect(apiKey);
 }, this.TIMEOUT);
 this.connections[apiKey] = { conn, timer };
 console.log(`✅ Connected to tenant DB for API key: ${apiKey}`);
 return conn;
 }
 /**
 * Disconnect tenant DB
 */
 async disconnect(apiKey) {
 if (this.connections[apiKey]) {
 await this.connections[apiKey].conn.close();
 clearTimeout(this.connections[apiKey].timer);
 delete this.connections[apiKey];
 console.log(`❌ Disconnected tenant DB for API key: ${apiKey}`);
 }
 }
 /**
 * Register a model on a tenant connection
 */
 async setModel(apiKey, dbURI, modelName, schema) {
 const conn = await this.getConnection(apiKey, dbURI);
 if (!conn.models[modelName]) {
 try {
 conn.model(modelName, schema);
 } catch (err) {
 if (err.name !== "OverwriteModelError") throw err;
 }
 }
 return conn.model(modelName);
 }
 /**
 * Get a registered model
 */
 async getModel(apiKey, dbURI, modelName) {
 const conn = await this.getConnection(apiKey, dbURI);
 if (!conn.models[modelName]) {
 throw new Error(
 `Model "${modelName}" not registered for tenant ${apiKey}`
 );
 }
 return conn.model(modelName);
 }
}
export default new TenantConnectionManager();