How to use the command mongosh (with examples)

mongosh is a new shell for MongoDB and is intended to replace the existing mongo shell. It provides a user-friendly interface for interacting with MongoDB databases. In this article, we will explore different use cases of using the mongosh command.

Use case 1: Connect to a local database on the default port

Code:

mongosh

Motivation:

This use case allows us to connect to a local database on the default port (mongodb://localhost:27017). It is useful when we want to quickly connect to a MongoDB database without specifying any additional parameters.

Explanation:

• No arguments are provided to the mongosh command.
• The default connection options are used to connect to the local database.

Example output:

Current Mongosh Log ID: XXXXXXXXXXXXXXXXXX
Connecting to:          mongodb://127.0.0.1:27017/?directConnection=true&serverSelectionTimeoutMS=2000
Using MongoDB:          4.4.6
Using Mongosh:          1.0.5

For mongosh info, press Ctrl+D

Use case 2: Connect to a database

Code:

mongosh --host host --port port db_name

Motivation:

This use case allows us to connect to a specific database on a MongoDB server. It is useful when we want to work with a specific database and know the host and port information of the server.

Explanation:

• The --host argument is used to specify the hostname or IP address of the MongoDB server.
• The --port argument is used to specify the port number of the MongoDB server.
• The db_name argument is used to specify the name of the database to connect to.

Example output:

Current Mongosh Log ID: XXXXXXXXXXXXXXXXXX
Connecting to:          mongodb://host:port/db_name?directConnection=true&serverSelectionTimeoutMS=2000
Using MongoDB:          4.4.6
Using Mongosh:          1.0.5

For mongosh info, press Ctrl+D

Use case 3: Authenticate using the specified username on the specified database

Code:

mongosh --host host --port port --username username --authenticationDatabase authdb_name db_name

Motivation:

This use case allows us to authenticate using a specified username on a specific MongoDB database. It is useful when we want to connect to a database that requires authentication.

Explanation:

• The --host argument is used to specify the hostname or IP address of the MongoDB server.
• The --port argument is used to specify the port number of the MongoDB server.
• The --username argument is used to specify the username for authentication.
• The --authenticationDatabase argument is used to specify the name of the authentication database.
• The db_name argument is used to specify the name of the database to connect to.

Example output:

Current Mongosh Log ID: XXXXXXXXXXXXXXXXXX
Connecting to:          mongodb://username@host:port/db_name?authSource=authdb_name&directConnection=true&serverSelectionTimeoutMS=2000
Using MongoDB:          4.4.6
Using Mongosh:          1.0.5
Enter password:
Authentication successful

For mongosh info, press Ctrl+D

Use case 4: Evaluate a JavaScript expression on a database

Code:

mongosh --eval 'JSON.stringify(db.foo.findOne())' db_name

Motivation:

This use case allows us to evaluate a JavaScript expression on a MongoDB database. It is useful when we want to perform complex database operations or retrieve specific data using JavaScript expressions.

Explanation:

• The --eval argument is used to specify the JavaScript expression to evaluate.
• The JavaScript expression should be enclosed in single quotes.
• The db_name argument is used to specify the name of the database to connect to.

Example output:

Current Mongosh Log ID: XXXXXXXXXXXXXXXXXX
Connecting to:          mongodb://127.0.0.1:27017/db_name?directConnection=true&serverSelectionTimeoutMS=2000
Using MongoDB:          4.4.6
Using Mongosh:          1.0.5

{\"_id\": \"XXXXXXXXXXXXXXXX\", \"name\": \"John Doe\", \"age\": 30}

For mongosh info, press Ctrl+D

Conclusion:

The mongosh command provides a flexible and user-friendly way to interact with MongoDB databases. Whether you need to connect to a local or remote database, authenticate with a specific user, or evaluate JavaScript expressions, mongosh has you covered. Use the provided examples to get started with using mongosh for your MongoDB database needs.