RoR.txt

$ rails new <app_name>				// initialie rails app
$ bundle install 					// bundler install GEMs
$ rails server 						// runs rails application
$ rails s -p 8080					// start server
$ rails generate model <model_name>	// model names are capitalized and singular
$ rails generate controller <ctrl_name> // controller names are capitalized and plural
$ rake routes						// view all routes
$ rake db:migrate					// migrate database
$ rake db:seed						// seed database
$ rails console

// Database query
// database queries can be chained toegether
TableName.find(<id>) // also works for multiple id queries
TableName.all
TableName.first
TableName.last
TableName.count	// count of entires in table
TableName.order(:attr) // returns all entries ordered by attribute :attr
TableName.limit(10)	// returns first 10
TableName.where(<attribute>: <value>)	// returns all entries with <attribute> of <value>
TableName.destroy_all	// clears all entries
Create
	t = TableName.create
	// update t values
	t.save // save an entry based on its model validation
OR
Create
	t = TableName.create
	t.update(	// in this case don't need to save, update takes care of that
		<attrname>: <new value>
		...
	)

Read
	TableName.find(<id>) // also works for multiple id queries
Update
	t = TableName.find(<id>)
	// update t values
	t.save
	# .save method returns true if successfully saved, false otherwise

Delete
	t = TableName.find(<id>)
	t.destroy

Model
	class <capitalized singular model name> < ActiveRecord::Base
	# model validations 
		validates_presence_of :attribute 			// ensures that entry will always have value defined in :attribute
		validates_numericality_of :attribute 		// ensure ensures that entry will always have numeric value defined in :attribute
		validates_uniqueness_of :attribute			// ensure ensures that entry will always have unique value defined in :attribute
		validates_confirmation_of :attribute
		validates_acceptance_of :attribute			// for e.g. checkboxes that have to be indicated true
		validates_length_of :password, minimum: 3 	// ensures passsword field in entry have minimum length of 3
		validates_format_of :email, with: /regex/i 	// ensures format of email complies with regex
		validates_inclusion_of :age, in: 21..99 	// ensures age is within range (21..99)
		validates_exclusion_of :age, in: 0..21 		// ensures age is not within range (21..99)
		# shorthands
			validates :attribute, presence: true
			validates :attribute, length: {minimum:3}
			# combining the above two:
				validates 	:attribute, 
							presence: true,
							length: {minimum:3}

	# using relationships
		belongs_to :<singular>
		has_many :<plural>
		ash = Zombie.find(3)
		t = Tweet.create(status: "some tweet", zombie: ash)
		t.zombie # returns the Zombie(lowercase) object that t belongs to

View
	# link
	<%= link_to '<link text>',<model name>_path(<entry obj>) %>
	<%= link_to '<link text>', <entry obj>) %> # shorthand
	<%= link_to '<link text>', <entry obj>, confirm: "Are you sure?") %> # confirm text
	<%= link_to '<link text>', edit_<model name>_path(<entry obj>)) %> # Edit
	<%= link_to '<link text>', <entry obj>, method: :delete %> # Destroy
	# URL generator methods. Note <model name> is in lowercase
		<model name>s_path					# redirects to /<model name>s
		new_<model name>_path 			# redirects to '<model name>s/new'
		<model name>_path(<entry obj>)	# redirects to <model name>s/<entry obj>.id
		edit_<model name>_path(<entry obj>)	# redirects to <model name>s/<entry obj>.id/edit
		<model name>, method: :delete 	# redirects to <model name>s/<entry obj>.id

controller
	class <Model name capitalized>sController < ApplicationController



sudo -u postgres psql postgres