@notross/mongo-singleton/esm/client.js

A lightweight, zero-fuss way to get a single shared MongoDB connection across your Node.js codebase.

import { MongoClient, ServerApiVersion } from 'mongodb';
import { buildConnectionString, Logger } from './utils';
const mongodbConfig = {
    serverApi: {
        version: ServerApiVersion.v1,
        strict: true,
        deprecationErrors: true,
    },
};
const logger = new Logger();
/**
 * MongoSingleton
 *
 * Manages a single, shared MongoDB connection for the application.
 * Subsequent calls to `.connect()` return the same connection.
 *
 * Like me, it's single and looking for a connection. 💔
 */
export default class MongoSingleton {
    /**
     * @param connectionProps - Either a full ConnectionProps object, a SparseConnectionProps object, or a raw MongoDB URI string.
     * @param database - The name of the database to operate on.
     */
    constructor(connectionProps, database) {
        this.client = null;
        this.database = null;
        this.status = 'Disconnected';
        this.error = null;
        this.initializeLogging(connectionProps);
        this.databaseName = database;
        if (typeof connectionProps === 'string') {
            this.uri = connectionProps;
        }
        else {
            this.uri = connectionProps.uri ||
                buildConnectionString(connectionProps);
        }
    }
    initializeLogging(props) {
        var _a, _b;
        const logging = typeof props === 'object'
            ? (_a = props.logging) !== null && _a !== void 0 ? _a : true
            : true;
        logger.toggleLogging(logging);
        const levels = typeof props === 'object'
            ? (_b = props.logLevels) !== null && _b !== void 0 ? _b : undefined
            : undefined;
        logger.setLevels(levels);
    }
    initializeClient() {
        if (this.client) {
            return this.client;
        }
        const client = new MongoClient(this.uri, mongodbConfig);
        return client;
    }
    initializeDatabase(client) {
        this.database = client.db(this.databaseName);
        return this.database;
    }
    getDb(client) {
        return this.database || this.initializeDatabase(client);
    }
    /**
     * Establishes a connection to MongoDB if not already connected.
     * If already connected, returns the existing client and database.
     *
     * @returns Promise resolving to the connected MongoClient and Db.
     * @example
     * const { client, database } = await mongoClient.connect();
     */
    async connect() {
        if (this.client) {
            return {
                client: this.client,
                database: this.getDb(this.client),
            };
        }
        this.client = this.initializeClient();
        await this.client.connect().then((client) => this.initializeDatabase(client));
        this.client.on('connectionReady', () => {
            this.status = 'MongoDB connection is ready';
            logger.log(this.status);
        });
        this.client.on('close', () => {
            this.status = 'MongoDB connection closed';
            logger.log(this.status);
        });
        this.client.on('error', (err) => {
            this.status = 'MongoDB connection error';
            this.error = err;
            logger.error(this.status, err);
        });
        this.client.on('reconnect', () => {
            this.status = 'MongoDB reconnected';
            logger.log(this.status);
        });
        this.client.on('reconnectFailed', () => {
            this.status = 'MongoDB reconnection failed';
            logger.error(this.status);
        });
        this.client.on('timeout', () => {
            this.status = 'MongoDB connection timed out';
            logger.error(this.status);
        });
        this.client.on('serverHeartbeatFailed', (err) => {
            this.status = 'MongoDB server heartbeat failed:';
            this.error = err;
            logger.error(this.status, this.error);
        });
        this.client.on('serverHeartbeatSucceeded', () => {
            this.status = 'MongoDB server heartbeat succeeded';
            logger.log(this.status);
        });
        this.client.on('serverClosed', () => {
            this.status = 'MongoDB server closed';
            logger.log(this.status);
        });
        this.client.on('serverOpening', () => {
            this.status = 'MongoDB server opening';
            logger.log(this.status);
        });
        return {
            client: this.client,
            database: this.getDb(this.client),
        };
    }
    /**
     * Gracefully closes the MongoDB connection and resets internal state.
     * If no client exists, logs a warning instead.
     */
    async disconnect() {
        if (this.client) {
            await this.client.close().then(() => {
                this.client = null;
                this.database = null;
                this.status = 'Disconnected from MongoDB';
                logger.log(this.status);
            }).catch((err) => {
                this.status = 'Error disconnecting from MongoDB';
                this.error = err;
                logger.error(this.status, err);
            });
        }
        else {
            this.status = 'No MongoDB client to disconnect';
            logger.warn(this.status);
        }
    }
}
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