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README.md

MongoDB

Installation

Docker

Start the MongoDB Docker image via Docker:

> docker run --rm --name mongo-demos --detach -p 27017:27017 mongo:4.2

Don't forget to stop it when you finish:

> docker stop mongo-demos

Maven

Start the MongoDB docker image via Maven:

> mvn docker:start

Don't forget the stop it once finished:

> mvn docker:stop

Mongo Shell

Install MongoDB Shell on macOS:

> brew tap mongodb/brew
> brew install mongodb-community-shell

Learn how to use it via the option -h,--help:

> mongo -h
MongoDB shell version v4.2.0
usage: mongo [options] [db address] [file names (ending in .js)]
db address can be:
  foo                   foo database on local machine
  192.168.0.5/foo       foo database on 192.168.0.5 machine
  192.168.0.5:9999/foo  foo database on 192.168.0.5 machine on port 9999
  mongodb://192.168.0.5:9999/foo  connection string URI can also be used
Options:
...

Interactive Mode

Connect to MongoDB via Mongo Shell:

> mongo

Once connected to MongDB via MongDB Shell, you can perform the following commands.

Display the current database:

> db
test

Switch to database test:

> use test
switched to db test

Check the MongoDB version:

> db.version()
4.0.0

Background Mode

Evaluate a string expression and return the result in JSON format. You can also use jq to transform it to something else.

mongo --quiet --eval "db.fruits.find({ ... })" | jq

Run a script and return the result in JSON format.

mongo --quiet find_fruits.js

Collections

Show collections:

> show collections
users
companies

Create a new collection (db.createCollection):

> db.createCollection("users")
{ "ok" : 1 }

Documents

Insert document(s) to collection:

> user1 = { "first_name": "Foo", "last_name": "Bar" }
{ "first_name" : "Foo", "last_name" : "Bar" }
> db.users.insert(user1)
WriteResult({ "nInserted" : 1 })
> db.users.insert([
...   { "first_name": "First1", "last_name": "Last1" },
...   { "first_name": "First2", "last_name": "Last2" },
... ])
BulkWriteResult({
	"writeErrors" : [ ],
	"writeConcernErrors" : [ ],
	"nInserted" : 2,
	"nUpserted" : 0,
	"nMatched" : 0,
	"nModified" : 0,
	"nRemoved" : 0,
	"upserted" : [ ]
})

Find documents from collection:

> db.users.find({ first_name: { $eq: "Foo" } })
{ "_id" : ObjectId("5e4908c14638a83462bc6a15"), "first_name" : "Foo", "last_name" : "Bar" }
{ "_id" : ObjectId("5e490a2a4638a83462bc6a16"), "first_name" : "Foo", "last_name" : "Bar2" }
> db.users.find({ first_name: "Foo" })
{ "_id" : ObjectId("5e4908c14638a83462bc6a15"), "first_name" : "Foo", "last_name" : "Bar" }
{ "_id" : ObjectId("5e490a2a4638a83462bc6a16"), "first_name" : "Foo", "last_name" : "Bar2" }
> db.users.find()
{ "_id" : ObjectId("5e4908c14638a83462bc6a15"), "first_name" : "Foo", "last_name" : "Bar" }
{ "_id" : ObjectId("5e490a2a4638a83462bc6a16"), "first_name" : "Foo", "last_name" : "Bar2" }

Update document(s) via db.collection.findAndModify. Although the query may match multiple documents, only one document will be modified ⚠️.

> db.users.findAndModify({ query: {}, update: { $set: { tel: "123" }}})
{
	"_id" : ObjectId("5e49118b095f13556162b497"),
	"first_name" : "First1",
	"last_name" : "Last1"
}

Update documents by adding a new field "tel" for all users:

> db.users.updateMany({}, { $set: { tel: "456" }})
{ "acknowledged" : true, "matchedCount" : 2, "modifiedCount" : 2 }

Update documents by adding a nested field "address.label" for all users:

> db.users.updateMany({}, { $set: { address: { label: "hi" }}})
{ "acknowledged" : true, "matchedCount" : 2, "modifiedCount" : 2 }

> db.users.find()
{ "_id" : ObjectId("5e4913e0095f13556162b499"), "first_name" : "Foo", "last_name" : "Bar1", "address" : { "label" : "hi" } }
{ "_id" : ObjectId("5e4913e0095f13556162b49a"), "first_name" : "Foo", "last_name" : "Bar2", "address" : { "label" : "hi" } }

Remove all documents from collection (:warning: be careful!):

> db.users.remove({})
WriteResult({ "nRemoved" : 4 })

Ports

The following table lists the default TCP ports used by MongoDB:

Default Port Description
27017 The default port for mongod and mongos instances. You can change this port with port or --port.
27018 The default port for mongod when running with --shardsvr command-line option or the shardsvr value for the clusterRole setting in a configuration file.
27019 The default port for mongod when running with --configsvr command-line option or the configsvr value for the clusterRole setting in a configuration file.

References