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npm

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package manager for node.js

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cannot find package

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express = require('express') in app.js

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so we have do npm install express

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also requires express and mongodb

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we could install these indivually or with package.json

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we just have to say npm install

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installs them in node_modules directory

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you could also install them globally

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helloworld in mongodb

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node.js driver

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communicates with mongod with BSON, a binary jSON

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driver is written in javascript

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handles things behind the scenes

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how to install

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cannot find module mongodb

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installs mongodb module

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var mc = require('mongodb').MongoClient;

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access the driver

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pass in a callback, it calls it when done connecting

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helloworld in express

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takes care of routing and details of web application for us

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callback takes two arguments

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app.get has respond and request in callback

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express server started on port 8080

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in app.get, the star is wildcard for any handler that is not handled

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extending helloworld in express

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make file views/hello.html

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<h1>Hello, {name}</h1>

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templating engine: consolidate

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a set of wrappers for template libraries for express

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app.engine('html',cons.swig);

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cons is consolidate and swig is the templating engine

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helloworld with mongodb, express, and swig

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adding calls to mongo db from the last example

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Server = require('mongodb').Server;

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told it to use the native BSON parser

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not registering a callback

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it looks like we are using our database connection before it is even connected

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but we actually start listening as soon as the database connection is open

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we are just setting up mongoClient as an object and then pass it as a parameter in the callback

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express: handling GET requests

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registering only one route

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app.get('/:name', ...

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uses this template

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express: handling POST requests

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form to pick radio button choice

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we have app.get and app.post

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express.bodyParser() populates req.body so we can access it

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error handling function

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call next with an error object

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mongodb is schemaless

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in RDBMS if you want to add a new field to a row, you need to create a new column for all rows in the table

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you don't need to do this in mongodb

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this allows mongodb to be very agile

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JSON

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there are only two data structures inside JSON

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arrays

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[...]

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dictionaries

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{ key : value, key : value }

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blog project

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database model if we used RDBMS

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database model in mongodb

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you can embed the comments in the posts

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if the email is missing from any comment, it doesn't matter, you can leave it out

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it is the way you access the data that guides how to design your data structures