Fork and clone this repository.

By the end of the lesson, students should be able to:

• Use the MongoDB shell to interact with MongoDB databases and collections
• Create, Read, Update, and Delete documents in MongoDB collections using the MongoDB shell.

Basic JavaScript.

Required readings:

• Completely unbiased explanation of noSQL
• Mongo DB Is Web Scale
• Getting Started with MongoDB (MongoDB Shell Edition)

We'll run brew install mongodb then execute the first two commands suggested.

Run sudo apt-get install mongodb

Relational databases are good at modeling data that fits into tables. What do you use if your data isn't that structured?

Perhaps a noSQL data-store.

MongoDB is a schema-less document-store that organizes documents in collections. What does this mean?

We'll use mongo-crud as the database to hold our tables and mongo to interact with it. mongo is MongoDB's command line client which lets us execute commands interactively and from scripts.

First let's fire up our server:

mongod

In a new tab start the mongo shell:

$ mongo mongo-crud
MongoDB shell version: 3.0.7
connecting to: mongo-crud
>

The command to list databases is show databases (or show dbs):

> show databases
local  0.078GB
>

Unlike PostgreSQL, MongoDB lets us select a database that hasn't been created. When we add a collection, the database will be created.

If we didn't specify the database on the command line we can connect to a database with use <database name>:

MongoDB shell version: 3.0.7
connecting to: test
> use mongo-crud
switched to db mongo-crud
> show databases
local  0.078GB
>

Our first collection will be called people. It has no entries.

> show collections
> db.people.count();
0

This is a common pattern in MongoDB: you can refer to things that don't yet exist, and it will cooperate. MongoDB won't create them until you give it something to remember.

• Inserting data - Overview of adding documents to a collection.
• db..insert() - detailed documentation of MongoDB's insert collection method.
• Importing data - overview of MongoDB's mongoimport command line utility.
• mongoimport - detailed documentation of MongoDB's mongoimport command line utility.

MongoDB's mongoimport command will let us load bulk data from a JSON or CSV file.

First we'll load data in bulk from sample-data/csv/people.csv. We'll save the command in scripts/import/people.sh.

mongoimport --db=mongo-crud --collection=people --type=csv --headerline --file=sample/csv/people.csv

If we want to clear the collection before the import we pass the --drop flag.

Run this script by typing:

sh path_to_file.sh

Now that we've inserted data into it, the mongo-crud database and the people collection both exist.

$ mongo mongo-crud
MongoDB shell version: 3.0.7
connecting to: mongo-crud
> show dbs
local       0.078GB
mongo-crud  0.078GB
> show collections
people
system.indexes
> db.people.count();
2438

Next we'll use the insert collection method to add a few more people. We'll save our invocations in insert/people.js. We'll execute that script using the mongo load method. Let's give these people a middle_initial or a nick_name. Note that the attributes we choose for these people need not match those from the data we loaded in bulk.

> load('scripts/insert/people.js');

MongoDB uses JSON natively (technically BSON), which makes it well suited for JavaScript applications. Conveniently, MongoDB lets us specify the JSON as a JavaScript object.

Together we'll add a few cities then we'll bulk load sample-data/csv/cities.csv.

Add a pet to the pets collection using insert then bulk load sample-data/csv/pets.csv.

Next add a person to the people collection using insert then bulk load sample-data/csv/people.csv.

• Querying - Overview of retrieving data from MongoDB.
• Queries - More detailed overview on retrieving data.
• find - Detailed documentation on the find collection method.
• findOne - Detailed documentation on the findOne collection method.
• Data aggregation - Overview of summarizing documents.
• aggregate - Detailed documentation on the aggregate collection method.

Let's see some what we can learn about the people in the database.

Note: When using the REPL the .pretty() method can be quite helpful.

What do we see?

• MongoDB gave each of our documents a unique ID field, called _id.

• MongoDB doesn't care that some documents have fewer or more attributes.

Together we'll build a query to get all the cities. How about with some over a certain population size.

Woah, this looks like javascript. I wonder if we could use javascript?...

Write a query to get all the animals of a kind born before 2010.

Challenge: Using the docs select all animals that are fish, sort them by date.

• Updating Data - overview of changing documents
• update - detailed documentation of MongoDB's update collection method.
• Update Operators - The different modifications we can make during an update.

MongoDB makes it easy to add an array of items to a document. We'll update some people and give them some pets.

Let's update some cities population.

Update weight for pets then people.

• Removing Data - Overview of removing documents from a collection.
• remove - detailed documentation of MongoDB's remove collection method.

If we want to clean up, db.<collection>.drop(); drops the specified collection and db.dropDatabase(); drops the current database.

We'll remove a few people from the data-store.

Let's remove all the cities with CA as a region

Remove pets born before 1996 then people taller than 5'11".

• [BSON Types]https://docs.mongodb.org/manual/reference/bson-types/