Write Scripts for the MongoDB Shell¶
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You can write scripts for the MongoDB Shell that manipulate data in MongoDB or perform administrative operations.
This tutorial introduces using the MongoDB Shell with JavaScript to access MongoDB.
Open a New Connection¶
From the MongoDB Shell or from a JavaScript file, you can instantiate
database connections using the Mongo method:
new Mongo()
new Mongo(<host>)
new Mongo(<host:port>)note
The MongoDB Shell does not support the
ClientSideFieldLevelEncryptionOptions
document with the Mongo method.
Consider a MongoDB instance running on localhost on the default port.
example
The following example:
- Instantiates a new connection to the instance, and
- Sets the global
dbvariable tomyDatabaseusing theMongo.getDBmethod.
conn = Mongo();
db = conn.getDB("myDatabase");If you connect to a MongoDB instance that enforces access control, you must include the credentials in the connection string.
example
The following command connects to a MongoDB instance that is:
- Running on
localhoston the default port, and - Secured using SCRAM.
conn = Mongo("mongodb://<username>:<password>@localhost:27017/<authDB>");note
The MongoDB Shell redacts credentials from the command history and the logs.
Additionally, you can use the connect() method to connect to the MongoDB instance.
example
The following command:
- Connects to the MongoDB instance that is running on
localhostwith the non-default port27020, and - Sets the global
dbvariable.
db = connect("localhost:27020/myDatabase");Use require() to Include External Files and Modules¶
important
A complete description of Node.js, modules, and the require() function is out of scope for this tutorial. To learn more, refer to the Node.js Documentation.
You can use the require() function in the MongoDB Shell to include modules which exist in separate files.
Require a File¶
You can require() JavaScript files in the MongoDB Shell without any
additional setup or configuration.
note
The MongoDB Shell does not execute files imported with require().
The MongoDB Shell adds everything from an imported file to the current
execution scope.
example
Use one of the following commands include a file from the current
working directory named tests.js:
require('./tests.js')var tests = require('./tests.js')Require a Native Module¶
You can require() native Node modules (such as
fs) in the
MongoDB Shell without any additional setup or configuration.
example
Use one of the following commands to include the fs module:
require('fs')var fs = require('fs');Require a Non-Native Module¶
To require() non-native Node modules (such as those downloaded from
npm) you must install the module globally
or to the node_modules directory in your current working directory.
Once you install or copy your desired package to one of the module
directories, you can require() that package.
example
Use one of the following commands to include the moment:
require('moment')var moment = require('moment')Execute a JavaScript File¶
You can execute a .js file from within the MongoDB Shell
using the .load command.
example
The following command loads and executes the myjstest.js file:
.load myjstest.jsThe .load command accepts relative and absolute paths. If the
current working directory of the MongoDB Shell is /data/db,
and myjstest.js resides in the /data/db/scripts directory, then
the following calls within the MongoDB Shell are equivalent:
.load scripts/myjstest.js
.load /data/db/scripts/myjstest.jsnote
There is no search path for the .load command. If the desired
script is not in the current working directory or the full specified
path, the MongoDB Shell cannot access the file.