Docs Menu

Docs Home → Develop Applications → Python Drivers → PyMongo

Create a MongoClient

On this page

  • Overview
  • Connection URI
  • MongoClient
  • API Documentation

Overview

To connect to a MongoDB deployment, you need two things:

  • A connection URI, also known as a connection string, which tells PyMongo which MongoDB deployment to connect to.

  • A MongoClient object, which creates the connection to the MongoDB deployment and lets you perform operations on it.

You can also use either of these components to customize the way PyMongo behaves while connected to MongoDB.

This guide shows you how to create a connection string and use a MongoClient object to connect to MongoDB.

Connection URI

A standard connection string includes the following components:

Component
Description
mongodb://
Required. A prefix that identifies this as a string in the standard connection format.
username:password
Optional. Authentication credentials. If you include these, the client authenticates the user against the database specified in authSource. For more information about the authSource connection option, see Authentication Mechanisms.
host[:port]
Required. The host and optional port number where MongoDB is running. If you don't include the port number, the driver uses the default port, 27017.
/defaultauthdb
Optional. The authentication database to use if the connection string includes username:password@ authentication credentials but not the authSource option. If you don't include this component, the client authenticates the user against the admin database.
?<options>
Optional. A query string that specifies connection-specific options as <name>=<value> pairs. See Specify Connection Options for a full description of these options.

For more information about creating a connection string, see Connection Strings in the MongoDB Server documentation.

MongoClient

To create a connection to MongoDB, pass a connection URI as a string to the MongoClient constructor. In the following example, the driver uses a sample connection URI to connect to a MongoDB instance on port 27017 of localhost:

from pymongo import MongoClient
uri = "mongodb://localhost:27017/"
client = MongoClient(uri)

Tip

Reusing Your Client

Because each MongoClient object represents a pool of connections to the database, most applications require only a single instance of MongoClient, even across multiple requests. However, if you fork a process, the child process does need its own MongoClient object. To learn more, see the FAQ page.

API Documentation

To learn more about creating a MongoClient object in PyMongo, see the following API documentation:

← Connect to MongoDB
Choose a Connection Target →

On this page