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Create a MongoClient

This guide shows you how to connect to a MongoDB instance or replica set deployment by using the .NET/C# Driver.

Overview

Connecting to a MongoDB deployment requires the following components:

Connection URI, also known as a connection string, which tells the .NET/C# Driver which MongoDB deployment to connect to.
MongoClient object, which creates and sustains the connection to the MongoDB deployment and lets you perform data operations.

You can also specify connection settings in either of these components to customize the way the .NET/C# Driver behaves while connected to MongoDB.

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

Connection URI

A standard connection URI 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 authentication settings, 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 to the MongoClient constructor. In the following example, the driver uses a sample connection URI to connect to a MongoDB deployment running on port 27017 of localhost:

const string uri = "mongodb://localhost:27017/";
var client = new MongoClient(uri);

Manage MongoClient Disposables

When you use MongoClient, we recommend giving it a singleton lifetime scope. However, this might cause excessive memory usage and undisposed resources.

In v3.0 and later of the .NET/C# Driver, a new MongoClient implements IDisposable to dispose of resources while using a singleton lifetime scope. This implementation allows the MongoClient class and any classes that implement the IMongoClient interface to access a Dispose() method. After you dispose of the client, any member connections return an ObjectDisposedException error.

Disposing of MongoClient does not dispose of the cluster and the underlying connections. To dispose of these resources, call ClusterRegistry.UnregisterAndDisposeCluster(). To learn more about the ClusterRegistry.UnregisterAndDisposeCluster() method, see UnregisterAndDisposeCluster() in the .NET/C# Driver API documentation.

Configure the Connection

You can configure your connection in the following ways:

Specifying parameters in the connection URI
Specifying settings on a MongoClientSettings or MongoUrlBuilder object

To learn more about configuring your connection, see the Specify Connection Options guide.

API Documentation

To learn more about creating a MongoClient object with the .NET/C# Driver, see the following API documentation:

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