Anthony kossoff

Cheat Sheets are greate but they are not a substitute for learning the framework and reading the documentation as we most certainly have not covered every potential example here. Please refer to the Rails Command Line Docs for more information.

Command Line Generator Info

Reference

You can get all of this information on the command line.

rails generate with no generator name will output a list of all available generators and some information about global options. rails generate GENERATOR --help will list the options that can be passed to the specified generator.

Rails Migration

http://guides.rubyonrails.org/migrations.html

Migrations methods:

add_column
add_index
change_column
change_table
create_table
drop_table

Rails Models

Generating models

$ rails g model User

Associations

belongs_to

has_one

	# because i can never remember exactly how and when to use concat
	# when building content in helpers
	def nested_content
	content_tag 'div' do
	concat(content_tag 'span', 'span block')
	concat(tag 'br')
	concat(link_to 'root link', root_path)
	concat(tag 'br')
	concat(link_to('#') do
	concat(content_tag 'h2', 'Head \'em off')

	The default Postgresql installation on Mac OS X using homebrew includes a single extension - plpgsql (PL/pgSQL procedural language) but there are a number of them available in the lib directory (/usr/local/Cellar/postgresql/9.2.1/lib on my machine)

	To install an extension into the database, the easiest way I found was to open a database console using the 'rails db' command and then create it directly. I have seen mention of doing this in a Rails migration but this did not work for me.

	Note that an extension is installed in a specific database, rather than being added to all databases.

	The command to list the installed extensions is '\dx'

	$ rails db
	psql (9.2.1)

	-- show running queries (pre 9.2)
	SELECT procpid, age(clock_timestamp(), query_start), usename, current_query
	FROM pg_stat_activity
	WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%'
	ORDER BY query_start desc;

	-- show running queries (9.2)
	SELECT pid, age(clock_timestamp(), query_start), usename, query
	FROM pg_stat_activity
	WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%'