Databases, MongoDB, and Mongoose - ryantc94/Knights-of-Arthur GitHub Wiki

Relational Databases

• Tables
• Each Table has columns and the rows contain data
• each row/column block contains a primary key to id it
• Follows ACID
• http://r937.com/relational.html
• Examples: MySQL, PostgreSQL, Oracle, Microsoft SQL Server

NoSQL

• Types

1. key-value: like a dictionary / hash map
2. Document: like JSON (MongoDB)
3. Column
4. Graph … https://en.wikipedia.org/wiki/NoSQL#Types_and_examples_of_NoSQL_databases

MongoDB

• Document is a single record in MongoDB
• Collection is a group of documents

Commandline

• mongod: to start mongodb
• mongo: to connect client to local instance

Shell Commands

• show databases

• use [database] <- adds a database

• show collections

• db.dropDatabase()

• db.collectionName.drop()

• help

• CRUD (create, read, update, delete)

• db.[collection].insert(obj)

• db.[collection].find(obj)

• db.[collection].update(obj, obj)

• db.[collection].remove(obj)

Mongoose

• schema: same as a collection
• model: actual constructors used to create objects
• object: same as document
• Mongoose only throws error when there is actually an err, not finding something is not an error https://stackoverflow.com/questions/38329730/mongoose-always-return-null-instead-of-an-error-when-no-result-found

ORM/ODM (how do these work???)

• map objects in your app to their counterparts in your database

Steps:

Create file called db.js

const mongoose = require(‘mongoose’);
mongoose.connect(‘mongodb://localhost/catdb);

//Create Schema

const Test = new mongoose.Test({
name: String,   <- Datatype
updated_at: Date
});

//register Schema

mongoose.model(‘Test’, Test)

App.js 

// initializes connection to db
require(./db)

Routes

const mongoose = require(‘mongoose’)
const Test = mongoose.model(‘Test’)

.post(url, function(req, res) {
new Test({
name
update
}).save(function(err, test, count) {
res.redirect
})
})

Embedding Documents

Foo: [Bar] <- Foo contains array of Bar

Field Specifications

type max min
required default

Slugs ???