Rails 1st Lecture

Rails Lecture I – July 2

How the web works:
-the requests we send to other servers have headers with info about the request
-you get the response with a header and the body
-the body is just text and data with HTML
-the communication happens over TCP/IP, namely HTTP
– the browser renders the HTML by making it pretty
-we use GET, POST, PUT, and DELETE –

4 imporotant HTTP Verbs–>
GET- retrieve representation of content
POST- Submits data
PUT- Update
Delete- Deletes a specific resource

Convention over configuration
-we wants defaults

There are naming schemes such as:
all tables pl
all models are sigular
controller songs_controller.rb
views songs/

pre-packaged piece of software that ruby uses

Config Folder–> where the configuration of our app lives
-Database.yaml- this is how we communicate the database

App Folder: spend most of our time in the app directory

MVC: (7:42 pm)
Models: define how data is created, retrieved, updated and deleted–> the only code that defined these 4 actions are in the model

Controllers: where to send the data to
business logic

Views: display logic

Helpers: helper functions for your views
db: stores your database and all the instructions for your database

lib: code that you app needs but isn’t part of the request cycle
-tasks- background tasks

public dir:
any code that doesn’t require the rails stack to run

vendor: any 3rd party library that you didn’t write
— similar to the lib directory that you didn’t write

-Representational State Transfer
-URL: unifeied resources locators
– there should be a unified way to expose resources to the world
-1st concept: the things we get online are resources– what the server is going to respond with is a representation of the real thing (since it can’t deliver the real thing)
-there should be consistency and predictability-

rails generate resource song title:string duration:integer #always singular
rails generate scaffold song title:string #in the beginning the first few resources are created by scaffolds

MIGRATION: defines a db strcuture
every resource has it’s own table

SQL: server query language or standard query language

SCHEMA- describes the structure of the DB

RAKE: a ruby library to run background tasks
rake stats– gives me stats on the app
rake about–> outputs info about the environment, etc
rake -T –> outputs provides commands


migrations are iterative by nature
every migration should one and only one thing

rake db:migrae runs the migration
rake db:rollback rolls back the migration

-what to create metaphors in our code to representations of the real world

Song.find(2) #=> finds the object of id 2
Song.all #=> returns all the instances of the class

ORM: object relational mappers
– a class is to a table : an instance of a class is to a row of a table
-every instance is going to wrap a row of a table
-one to one relationship between an instance and a row
-the library, the ORM, allows you to relate to the objects with knowing how the objects are related

Programming is just codifying procedural knowledge

Rails Guides: more like how-tos
Rails API: the more technical version


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