This article documents how Mongo DB CLI tool can be used to manipulate data.

mongo_db_notes.md

MongoDB Notes

MongoDB provides several ways to manipulate data:

• mongo / mongosh: CLI
• Compass: GUI

This document focuses on the usage of CLI.

1. MongoDB Installation (Mac OS)

brew install mongodb-community

To start MongoDB:

brew services start mongodb/brew/mongodb-community

or, for short,

brew services start mongodb-community

To stop MongoDB:

brew services stop mongodb-community

To restart MongoDB:

brew services restart mongodb-community

2. Usage

1. Launch CLI: MongoDB Legacy Shell or MongoDB Shell.

   • MongoDB Legacy Shell (deprecated in MongoDB v5.0):

     mongodb

   • MongoDB Shell (introduced in MongoDB v4.0):

     mongosh

2. Display the database being used.

   db

3. Show all database instances.

   show dbs

4. Switch to a database instance.

   use examples

5. To create a new database, first switch to a non-exist database and then insert a document.

   use products
   db.products.insertOne({
     name: 'Beautiful Wardrobe',
     description: 'This is a beautiful wardrobe that you shouldn\'t miss!',
     brand: 'Wonderful',
     category: 'Wardrobe',
     likes: 4,
     tags: ['wardrobe', 'bedroom'],
     size: {
       depth: '150',
       height: '180',
       width: '200',
       unit: 'cm'
     },
     date: Date()
   })

6. Insert many documents.

   db.products.insertMany([
     {
       name: 'Beautiful Bed Frame (Double)',
       description: 'This is a beautiful wardrobe that you should never miss!',
       brand: 'Wonderful',
       category: 'Bed Frame',
       tags: ['bed frame', 'bedroom'],
       size: {
         height: '1\'',
         length: '6\'3',
         width: '4\'6'
       },
       date: Date()
     },
     {
       name: 'Wonderful Bed Frame (Single)',
       description: 'This bed frame is really wonderful!!!',
       brand: 'Wonderful',
       category: 'Bed Frame',
       tags: ['bed frame', 'bedroom'],
       size: {
         height: '1\'',
         length: '6\'3',
         width: '3\''
       },
       date: Date()
     },
     {
       name: '3-seats Sofa',
       description: 'Comfortable sofa',
       brand: 'Wonderful',
       category: 'Sofa',
       tags: ['sofa', 'living room'],
       size: {
         height: '100',
         length: '200',
         width: '60',
         unit: 'cm'
       },
       date: Date()
     }
   ])

7. Find all documents.

   db.products.find()

8. Find by criteria.

   db.products.find({ category: 'Wardrobe' })

   • To print pretty in legacy Mongo shell

   db.products.find({ brand: 'Wonderful' }).pretty()

9. Find by limiting number of documents returned.

   db.products.find().limit(2)

10. Find only one document.

    db.products.findOne({ category: 'Wardrobe' })

11. Find by descending order.

    db.products.find().sort({ category: -1 }).limit(2)

12. Print documents.

    db.products.find().forEach(function(doc) { print('Product Name: ' + doc.name) })

13. Update single document, even if more than one document is found.

    db.products.update(
      { name: 'Beautiful Bed Frame (Double)' },
      {
        $set: {
          date: Date(),
          likes: 3
        }
      },
      {
        upsert: true
      }
    )

14. Update all matched documents.

    db.products.updateMany(
      { brand: 'Wonderful' },
      {
        $set: {
            brand: 'Wonderful',
            date: Date()
        },
        $unset: {
            likes: 4
        }
      }
    )