MongoDB Shell Commands Cheat Sheet.

This is a Cheat Sheet for interacting with the Mongo Shell ( mongo on your command line). This is for MongoDB Community Edition.

Preface:

1. After installing MongoDB and successfully running mongod to run the mongo service, open a new terminal window and type mongo to open a Mongo Shell.
2. You should see your command line change and be replaced with a > symbol. If you type db and see test or some other response then you have succesfully entered into the Mongo Shell and can start testing out the commands in this doc!

If you've never used the Mongo shell before, then I recommend skimming through these 3 doc as you read through this doc:

Mongo Manual can help you with getting started using the Shell.

FAQ for MongoDB Fundamentals and other FAQs can be found in the side-bar after visiting that link.

The Mongo Shell reference can be found here.

Quick Start

You can execute JavaScript commands in the shell. Type these commands into your commandline:

1. use sampleDB

• This makes a new database called sampleDB. It has no collections yet so it's not actually saved yet, which is why if you type show dbs it doesn't show up.

2. db.cars.insert( [{make:"Honda", doors:2}, {make:"VW", doors:4}] )

• This makes a new collection called cars and inserts 2 documents into it. .insert() will make the collections if it doesn't already exist. Now that our db has a collection, if you type show dbs you will see it listed with the rest of the databases.

3. db.cars.find({})

• This will list all the cars in your database.

This is where it gets fun:

1. let tempCar = {make: "Ford", doors:3}
2. db.cars.insert(tempCar)
3. db.cars.find({}).forEach(car => print(`${car.make} has ${car.doors} doors.`))

Notice that not only do we see out new Ford in our database, but we also get 3 messages printed out to the shell.

Note: Just because we can use JavaScript in the Shell doesn't mean we can use these same commands in Node.js though:

"JavaScript in MondgoDB: Although these methods use JavaScript, most interactions with MongoDB do not use JavaScript but use an idiomatic driver in the language of the interacting application."

This means that if we want to build an application then we should use the library provided by MongoDB. The Node.js Docs are found here.

Docs

Anything that looks like db.<something>() will be found in Database Methods.

Anything that looks like db.collection.<something> will be found in Collection Methods.

Use db.help() to get a list of all database commands. ( Note that it's pretty long.)

Anything in < > should be replaced with your unique values. IE: You want to have a database called Cars you would use the command use <db> but you would type it as use Cars.

Databases:

This table will list the commands most commonly used when working with the database as a whole.

Collections:

This Table lists the commands most commonly used when working with collections as a whole.

Data

This section is broken down into 5 sub-sections. The first 4 match the CRUD Verbs of Create, Read, Update, Delete, and the last one is a list of Combos like findAndUpdate. Check here for the Mongo Docs on Crud

Couple notes here:

1. All of these commands start with db.<collection> where <collection> is the name of the collection you want to call these methods on. Any exceptions will be noted in the description.
2. {query} Is referring to queries like {<field>: '<value>', <field>:'<value>', etc). IE: { book: 'Golden River Doth Flows', author: 'I.P. Freely', etc}. They are field-value pairs that are used to make documents, and also used during searches, aka queries.

Create

Read

Most of these commands allow methods to be chained onto them.

Update

Delete

Combos

These are some combo commands that really just do the same thing as their base commands, but have a couple extra options.

All of these can leave their {query} blank and it will find the first document and execute it's verb on that item.