kdszafranski/prime-mongo-crud-lecture-notes

Mongo CRUD/Intro Lecture Notes

Open Mongo shell: mongo

Database

Create a new datbase called 'sigma':

use sigma

Create a new Collection called 'books':

db.createCollection('books')

Create a session variable as a short-hand:

var books = db.books

List Collections in current db

show collections

CRUD Syntax

CRUD Operations Docs

Create (Insert)

books.insert({
  title: "Snow Crash",
  author: "Neal Stephenson",
  edition: 1.2
  });

See what's in the Collection.

books.find()

books.findOne() Returns the first Document that matches.

Query criteria needs quotes if the field name has dots in it.

books.find({title: "Snow Crash"})

books.find({"ratings.1.score": 999})

Examples to Insert

books.insert({ title: "A Tale of Two Cities", author: "Charles Dickens", edition: 2, published: new ISODate('1859-5-20') });

books.insert({ title: "Murder on the Orient Express", author: "Agatha Christie", edition: 2 });

books.insert({ title: "Snow Crash", author: "Neal Steve", edition: 1.2, ratings: [ {score: 5}, {score: 1} ] });

books.insert({ title: "Catcher in the Rye", author: "Someone", edition: 1, ratings: [ {score: 2}, {score: 5}, {score: 3.5}, {score: 4} ]} );

Read (Find)

All books in our Collection:

books.find(); or books.find({})

Make it pretty by chaining .pretty() onto your query.

books.find().pretty()

Specific:

books.find({title: "Snow Crash"});

Like Search:

books.find({title: /Cat/});

$exists checks if this Document has a property/field.

books.find( {ratings: {$exists: true} } )

Query Operators

By Date. Before today:

books.find({published: {$lt: new Date('2016-11-28')}})

Find based on given edition numbers range

books.find({'edition':{$lt: 3}, 'edition':{$gt: 1.2} })

Partial List

• $lt, $gt (less-than, greater-than)
• $lte, $gte (less-,greater-than or equals)
• $ne (not equal)
• Implicit AND is used when multiple fields are specified.
• Explicit $and possible

Update

books.update()

books.update({title:"Catcher in the Rye"}, {$set: author: "J. D. Salinger"});

Arrays

Push into an existing array on a Document:

books.update({title: "Catcher in the Rye"}, {$push: {ratings: {score: 4.5}}})

books.update({title: "Catcher in the Rye"}, {$push: {ratings: {score: 9}}})

Update a value in an array

Find It:

books.find({title: "Catcher in the Rye"})

Update It:

books.update({title: "Catcher in the Rye"}, {$set: {"ratings.1.score": 999}})

Delete (Remove)

books.remove({"_id" : ObjectId("583dc0b4482c7736c1d27058")}) 583dc0b4482c7736c1d27058