Skip to main content
100%

MongoDb singleton connection in NodeJs

✓ Published0🌍 Public
Aackuser
Last edited Apr 5, 2013
Created on Nov 24, 2016

This example shows a singleton pattern for a MongoDB connection in Node.js, ensuring only one database connection is reused across the application. The code uses the `mongodb` library’s `Db`, `Connection`, and `Server` constructors to create a connection to a local database at `127.0.0.1` with `auto_reconnect` enabled. A module-level `connectionInstance` variable caches the open connection; on each call, the exported function either returns the cached instance via a callback or opens a new one if none exists. The approach avoids repeated connection overhead by relying on the `db.open` method.

AI-generated description

Similar vizzes

Loading thumbnail…

Gist 444255

This example demonstrates a Node.js server that queries MongoDB collections and logs their contents to the console, primarily as a backend testing or debugging tool. The code uses the `mongo.Db` and `mongo.Server` APIs to connect to a local MongoDB instance on port 27017, then defines HTTP routes via a `get()` handler. For each route, it retrieves documents from specific collections—`some-collection` and `another-collection` (the latter with a limit of 10)—and prints each item using `sys.puts` and `sys.inspect`. The visualization aspect is absent; the example focuses on database interaction and response handling.

CCaged
59% match
Loading thumbnail…

use node.js to copy from one mongo db to another

This example shows how to copy a MongoDB collection from one database to another using Node.js. The script opens both source and target databases via `mongodb.Server` and `mongodb.Db`, authenticates with credentials parsed from the URLs, then uses `sourceCollection.find().toArray()` and `targetCollection.insert()` to move all documents. It relies on the native MongoDB driver and Node’s `url.parse` for connection details, logging the number of inserted documents on success or exiting with an error otherwise.

RRandomEtc
56% match
Loading thumbnail…

Notify socket.io users when MongoDB data collection changes

This example shows how MongoDB data changes are streamed to connected Socket.io users in real time. It uses the MongoDB `User.watch()` change stream to monitor collection modifications, and on each change, queries all users via `User.find({})` before emitting the updated dataset through `socket.emit('users', data)`. The code integrates with an Express app and a Socket.io server, logging connection events and collection changes to the console. No visualization library is involved; the focus is on the backend data pipeline that pushes fresh data to clients.

Aackuser
51% match
Loading thumbnail…

The correct shared module for Nest.js - https://blog.entrostat.com/setting-up-a-database-module-in-nest-js/

This example shows how to structure a shared Nest.js module that integrates TypeORM with a database connection. The `SharedModule` imports `DatabaseModule` and uses `TypeOrmModule.forFeature` to register the `User` entity for a specific database connection, while also exporting `DatabaseModule` and `UserService` for reuse elsewhere. The code relies on Nest.js decorators like `@Module`, `@Injectable`, and the TypeORM API, with configuration accessed via `Config.get.databases.main.name`.

Aackuser
51% match
Loading thumbnail…

Gist 3999923c627bd9069b071df1ecf6864f

This example demonstrates how to configure a MySQL database connection using the Knex.js query builder. The code explicitly defines a client as `mysql` and passes connection parameters such as `host`, `user`, `password`, and `database` from environment variables (`process.env.jimDBHost`, etc.). It illustrates the typical setup pattern for connecting Knex to a MySQL server, preparing the connection object for subsequent queries. The visualization highlights the structure of the `require('knex')({...})` initialization call, focusing on the configuration object that specifies both the client type and the secure credential handling through environment variables.

JJWTappert
50% match
Loading thumbnail…

[远程数据库导出 Mongodb] #mongodb

This example demonstrates a command-line workflow for exporting a remote MongoDB collection to a local JSON file. The script uses the `mongoexport` utility with explicit `--username`, `--password`, `--host`, `--port`, and `--authenticationDatabase` parameters to authenticate against the `admin` database, then extracts documents from the `spider_resume_test` collection in the `spider` database. It also applies `--skip` and `--limit` options to paginate the export, writing the results to `cv.json` on the desktop. The command shows a direct CRUD operation without any visualization library; the output is a raw data file rather than a rendered chart.

SShawn91
50% match
Loading thumbnail…

Notify socket.io users when MongoDB data collection changes

This example shows a real-time notification system that pushes MongoDB collection changes to connected socket.io clients. The code sets a watch on the User collection using MongoDB’s changeStream API, then listens for socket connections. Upon any change event, it queries the full User collection with `User.find({})` and emits the updated data to the client via `socket.emit('users', data)`. It demonstrates live data synchronization between a MongoDB backend and browser clients through socket.io’s event-driven communication.

Aackuser
50% match
Loading thumbnail…

Mongo Basics Drills

This example shows a series of MongoDB shell commands that demonstrate basic CRUD operations and query patterns against a restaurant dataset. The code performs actions like finding all documents, sorting and limiting results, retrieving documents by `_id` or field values, counting records, deleting single documents, and updating either one or many documents using `updateOne` and `update` with the `$set` operator. It also illustrates how to obtain an `ObjectId` from a query result and use it for subsequent operations. The visualization presents these commands as a linear drill sequence, making the MongoDB query syntax and workflow explicit.

Aarcox80
50% match