This is my note from Wilson Ren’s web dev course on Udemy. Wilson is using version 4.4.2 to build a demo project while I prefer to explore with newer version and add some structure and background knowledge to my wander.

Installation with homebrew #

Official document for installation on Mac:

https://www.mongodb.com/docs/v6.0/tutorial/install-mongodb-on-os-x/

brew tap mongodb/brew
brew update
brew install mongodb-community

# To start mongodb/brew/mongodb-community now and restart at login:
brew services start mongodb/brew/mongodb-community
brew services stop mongodb/brew/mongodb-community

# To verify that MongoDB is running, perform one of the following:
brew services list

# to use MongoDB
mongosh

# to use the MongoDB Database Tools
mongotop

The binary command to start MongoDB changed from mongo (v4.4)to mongosh(current version 6.0.6), which may cause some confusion. At first I ran mongo and mongod, and neither gave me correct response.

After checking /usr/local/bin(you can get this path by running brew --prefix) directory, I found all binary commands related with mongo, and legitimately guessed which to run.

list of mongo related binary commands:

mongod mongodump mongoexport mongofiles mongoimport

mongorestore mongos mongosh mongostat mongotop

As the document says: “The legacy mongo shell was deprecated in MongoDB 5.0 and removed in MongoDB 6.0. The new MongoDB Shell, mongosh, offers numerous advantages over the legacy shell. … Some legacy methods are unavailable or have been replaced with updated methods in mongosh. To maintain backwards compatibility, the legacy methods that mongosh supports use the same syntax as the corresponding methods in the mongo shell.”

Basic facts to know about MongoDB #

MongoDB is not relational database.
MongoDB use BSON instead of JSON to store things. BSON stands for Binary JSON. It is a binary encoded serialization of JSON documents, and supports more data formats than JSON - for example, float, and binary objects.
Collections in MongoDB is like tables in MySQL.
Mongo’s shell is a fully functional javascript shell, so it can process js code.

Basic commands #

Within mongosh console, here are some common commands to use:

db // to show current database
use [someDB]
use [anotherDB]
show dbs // to show all databases
show collections // to show all collections

CRUD #

Document: https://www.mongodb.com/docs/mongodb-shell/crud/

Create -> insert #

// db.collection.insertOne()
use sample_mflix
db.movies.insertOne(
  {
    title: "The Favourite",
    genres: [ "Drama", "History" ],
    runtime: 121,
    rated: "R",
    year: 2018,
    directors: [ "Yorgos Lanthimos" ],
    cast: [ "Olivia Colman", "Emma Stone", "Rachel Weisz" ],
    type: "movie"
  }
)

// db.collection.insertMany() pass an array of documents to method
use sample_mflix
db.movies.insertMany([
   {
      title: "Jurassic World: Fallen Kingdom",
      genres: [ "Action", "Sci-Fi" ],
      runtime: 130,
      rated: "PG-13",
      year: 2018,
      directors: [ "J. A. Bayona" ],
      cast: [ "Chris Pratt", "Bryce Dallas Howard", "Rafe Spall" ],
      type: "movie"
    },
    {
      title: "Tag",
      genres: [ "Comedy", "Action" ],
      runtime: 105,
      rated: "R",
      year: 2018,
      directors: [ "Jeff Tomsic" ],
      cast: [ "Annabelle Wallis", "Jeremy Renner", "Jon Hamm" ],
      type: "movie"
    }
])

Read(query) -> find #

// db.collection.find()
use sample_mflix
db.movies.find() // to return all documents from collection
// = SELECT * FROM movies

db.movies.find( { "title": "Titanic" } )
// = SELECT * FROM movies WHERE title = "Titanic"

db.movies.find( { rated: { $in: [ "PG", "PG-13" ] } } )
// = SELECT * FROM movies WHERE rated in ("PG", "PG-13")

db.movies.find( { countries: "Mexico", "imdb.rating": { $gte: 7 } } )
// implicit AND operator (there is no actual AND)

db.movies.find( {
     year: 2010,
     $or: [ { "awards.wins": { $gte: 5 } }, { genres: "Drama" } ]
} )
// explicit OR operator

Update -> update #

// db.collection.updateOne()
// $set
use sample_mflix
db.movies.updateOne( { title: "Twilight" },
{
  $set: {
    plot: "A teenage girl risks everything–including her life–when she falls in love with a vampire."
  },
  $currentDate: { lastUpdated: true }
})

// db.collection.updateMany()
use sample_airbnb
db.listingsAndReviews.updateMany(
  { security_deposit: { $lt: 100 } },
  {
    $set: { security_deposit: 100, minimum_nights: 1 }
  }
)

// db.collection.replaceOne()
db.accounts.replaceOne(
  { account_id: 371138 },
  { account_id: 893421, limit: 5000, products: [ "Investment", "Brokerage" ] }
)
db.accounts.findOne( { account_id: 893421 } )

Delete -> delete #

// db.collection.deleteMany()
// if want to delete all, pass an empty filter document {} to method
use sample_mflix
db.movies.deleteMany({})
db.movies.deleteMany( { title: "Titanic" } )

// db.collection.deleteOne()
// will delete only the first that matches condition
use sample_mflix
db.movies.deleteOne( { cast: "Brad Pitt" } )