deeply love rubyOnRails

中文字比較

2008-06-15T22:02:00.000-07:00

一個中文字利用3byte表示，

因此若要比較a="我愛妳"和b="妳愛我"的字首，

要比較 a[0]==b[0] && a[1]==b[1] && a[2] == b[2]

rails API

2008-06-11T10:05:00.000-07:00

api.rubyonrails.org

included & extend

2008-06-11T09:43:00.001-07:00

included:

the method defines the action to do when the class or module get included

extend:

extend the class's ability by including module

ex:

module M

end

Class C

end

c= C.new

c.extend(M)

note: use object to extend, get instance method,

use class to extend, get class method

class_eval

2008-06-11T09:29:00.000-07:00

define method for class

ex:

A=Class.new

A.class_eval do

def test

puts "test"

end

a=A.new

a.test

---> test

partial

2008-06-10T06:28:00.000-07:00

include the view in other file

ex:

render :partial=> "books"

render the view in _books.html.erb ( the partial view file must

start with _ )

ex:

render :partial => "rabbit/list"

render the view in different directory

note: the variable partial view can access is the variable the master view can access

self & method

2008-06-08T10:47:00.000-07:00

when there is a method ending with =, such as test=,

and there is another method run

In the definition of run, there are two conditions:

(1) test=3

this means test is a local variable

(2) self.test=2

this will call test method with parameter 2

Hence, when calling the method ending with = in the method definition, we can not omit self

association

2008-06-08T10:31:00.000-07:00

use class methods( has_one, belongs_to, has_many, has_and_belongs_to_many)

to create instance methods

has_one & belongs_to

has_many & belongs_to

has_and_belongs_to_many

the parameter for these methods:

:dependent => true

for delete.

ex:

class Customer <>

has_many :orders,

:dependent=>true

end

if the customer A is deleted, its orders are also deleted

:order

ex:

:order=>"created_at ASC"

ascending order according to created_at field

symbol

2008-05-26T10:13:00.000-07:00

change string to symbol:

use to_sym or intern

ex:

"test".to_sym

---> :test

change symbol to string

method 1: use to_s

method 2: use #{ }

ex:

"#{:abc}"

---> "abc"

methods

2008-05-25T03:05:00.000-07:00

methods:

A.methods:

show class methods

A.methods(false):

only show class methods of A, not including inherited methods

a.methods:

show instance methods of a

instance_methods:

A.instance_methods equals a.methods

A.instance_methods(false):

show only instance_methods 0f A, not including inherited methods

private_methods, public_methods, protected_methods, singleton_methods

compare: equal?, Comparable module

2008-05-25T02:53:00.000-07:00

check whether two objects are the same object

define how to compare

use Comparable module & define <=> method

the return value of method <=> , 1, 0 , & -1 decides greater than, equal than, & less than

ex:

class Rabbit

include Comparable

attr_accessor :name

def <=> (other_rabbit)

if self.name <>

-1

elsif self.name > other_rabbit.name

else

end

if the thing to compare know how to compare, there is a shorter definition

ex:

def <=> (other_rabbit)

self.name<=> other_rabbit.name

end

true, false & nil

2008-05-25T02:51:00.000-07:00

In Ruby, nil & false are the only two objects have boolean value of false

for, each

2008-05-24T19:40:00.000-07:00

for

ex:

for a in [1,2,3]

puts a

end

each

ex:

[1,2,3].each do |i|

puts i

end

loop, while, until

2008-05-24T19:36:00.000-07:00

loop

ex:

loop do

a=a+1

break if a>3

end

loop do

a=a+1

next if a <3

break

end

while

ex:

while a<3

end

until:

ex:

until a>3

end

case

2008-05-24T19:31:00.000-07:00

ex:

case name

when "peter"

puts "peter"

when "andy"

puts "andy"

else

puts "others"

end

how it works

translate to

if "peter" === name

note: the === method can be customarily defined

private & protected methods

2008-05-24T08:46:00.000-07:00

private method:

(1) use private with argument

ex:

private :test, :run

(2) use private

ex:

private

def test

end

def run

end

the methods after private are private

protected method:

use protected

can call the object's protected method as long as self is an instance of the same class as the object whose protected method is called

global variable

2008-05-24T08:41:00.001-07:00

start with $

built-in global variables:

$: the directories that make up the path Ruby searches for external file

$0: name of the file Ruby is executing

$$: process id of Ruby process

ps: use English.rb to replace these built-in global variables with meaningful names

instance variable

2008-05-22T22:04:00.000-07:00

In the class definition, the instance variable insides method & outside method are not the same

the instance variable inside method belongs to object

the instance variable outside method belongs to class

class & self

2008-05-22T21:47:00.000-07:00

In the class definition, self = class

so Rabbit.run = self.run

In the class-method definition, self = class

:: access

2008-05-22T21:39:00.000-07:00

(1) access constant

(2) access nested class

ex:

module ActionController

module Routing

class Route

....

end

ActionController::Routing::Route.new

ex:

class Rabbit <>

end

class ApplicationController <>

end

(3) access nested module

method_missing

2008-05-22T21:32:00.000-07:00

If the message sent to object is the message object can't understand, it will trigger execution of method_missing

Rails use method_missing to look up database & create methods

super keyword

2008-05-20T22:07:00.000-07:00

call the method of superclass or module

ex:

class A

def test(num)

puts "A test #{num}"

end

class B <>

def test( num)

super

puts "B test #{num}"

end

b= B.new

b.test(2)

---> A test 2

B test 2

super will pass the parameters to superclass or module

another usage: call super will parameters to pass specific parameters

root module & root class

2008-05-20T10:03:00.000-07:00

root class: Object

root module: Kernel

attr_reader, attr_writer,

2008-05-20T09:37:00.000-07:00

the getter:

ex:

attr_reader :name

the setter:

ex:

attr_writer :name

getter & setter:

ex:

attr_accessor :name

respond_to?

2008-05-18T07:14:00.000-07:00

check if the object has specific method

ex:

test.respond_to?("methods")

---> true

object_id

2008-05-18T07:11:00.000-07:00

Object's method

return the id of the object

ex:

a=3

b=a

now a & b have the same object id

the data controller can access

2008-05-14T22:02:00.000-07:00

CGI data:

access @params via params method

ex:

params[:id], params[:user][:age]

session information:

access @session via session method

ex:

session['user']

model's data

ex:

model Car has a name field

car is an instance of model Car

car.name

mysql command

2008-05-13T03:44:00.000-07:00

start mySQL:

sudo /usr/local/mysql/bin mysqld_safe

stop mySQL:

sudo /usr/local/mysql/bin mysqladmin shutdown

create an account for a database:

grant all on *.* to 'deeplove'@'localhost' identified by '111';

create new user account "deeplove", with password 111,

connect to database from "localhost", all means you can do anything( SELECT, INSERT, ...)

*.* means you can connect to every database ( Dog.* means you can only connect to Dog database)

join:

collect information from two or more tables & present it as a single table

left join ... on ... :

return all matching rows from first table, even if there are no matching rows in the second table

group by

combine two tables using the filed both tables have

select syntax

select columns from table where condition

rails source code location in mac

2008-05-12T10:50:00.000-07:00

/Library/Ruby/Gems/1.8/gems/rails-2.0.2

/Library/Ruby/Gems/1.8/gems/actionpack-2.0.2/lib

action_controller.rb & action_view.rb are in this folder

/Library/Ruby/Gems/1.8/gems/activerecord-2.0.2

require vs load

2008-05-12T10:03:00.000-07:00

ex:

require 'test'

second require is useless

ex:

load 'test'

second load will load test again

puts and print

2008-05-12T08:54:00.000-07:00

puts will print new line

print will not

gets

2008-05-12T08:35:00.000-07:00

get a line of input( in string)

paginate

2008-05-12T03:53:00.000-07:00

divide large collections into pages

ex:

in the controller:

def car_list

@car_pages, @cars = paginate ( :cars, :order_by => 'name')

end

@car_pages is a paginator object.

@cars contain 10 rows. ( default is 10 rows)

in the view:

table

for car in @cars

tr td car.name td tr

end

table

pagination_links(@car_pages)

pagination_links show the current page, two page numbers on either side of current page, first page & last page

helper

2008-05-11T07:32:00.000-07:00

remove the logic from view to helper

ex:

module TestHelper

def run

"test_title"

end

in the test controller

<%= run %>

originally the function in the helper file can only be accessed by related view,

but there is method for sharing helper

sharing helper:

method 1:

define the method in application_helper.rb

method 2:

ex:

add TestHelper to controller

helper :test

h( )

2008-05-11T07:14:00.000-07:00

escape html tag

ex:

<%= "<b>test</b>"% >

show test in bold

<%= h("<b>test</b>") %>

show <b%>test</b>

xml template

2008-05-11T06:40:00.000-07:00

builder template:

xml builder:

xml.tagName

ex:

xml.productName ( "car")

--> <productName>car</productName>

cache

2008-05-11T04:53:00.000-07:00

the page is cached .

Hence, after first request, the same URL's response is deliver from cache, rails is no involved

3 caches:

page caching, action caching & fragment caching

page caching:

ex:

caches_page :test

action caching:

execute filter before return cached pages

ex:

before_filter :test_filter

caches_action :test2

turn on caching( in environment.rb) :

ActionController::Base.perform_caching = true

removing cache:

expire_page

ex:

expire_page :action=>test

expire_action:

ex:

expire_action :action=>test2

sweeper:

observe the model. When the model is changed, the sweeper expire the cached pages that

depend on the model

ex:

in app/models

class TestSweeper <>

observe Car

def after_create(car)

expire_car_page

end

in app/controllers

class Test <>

cache_sweeper :test_sweeper

end

the location to store cached pages:

ex:

http://localhost:3000/content/show/1 is stored in app/public/content/show/1.html

verification

2008-05-11T04:39:00.000-07:00

verify that certain conditions are met

verify:

ex:

verify :session => :user_id,

:add_flash => { :note=> "you are wrong" }

:redirect_to => index

if the session does not contain key :user_id,

a note is added to flash & request is redirected to index

redirect_to

2008-05-10T19:31:00.000-07:00

three forms:

1. redirect_to ( options ... )

ex:

redirect_to (:action=>jump)

2. redirect_to (path)

ex:

redirect_to ("/test/run")

show /view/test/run.html.erb

3. redirect_to( url)

ex:

redirect_to("http://www.google.com")

logger

2008-05-10T08:27:00.000-07:00

4 levels:

warn, info, error, fatal

logger.warn("invalid number")

log file:

/log/development.log, /log/test.log, /log/production.log

group controllers into module

2008-05-10T07:46:00.000-07:00

For example, two directories Test1 & Test2,
controller Rabbit1Controller in Test1, Rabbit2Controller in Test2

url_for( :controller=> "rabbit1", :action=>"jump")
---> http://localhost:3000/test1/rabbit1/jump

rails program load sequence

2008-05-08T22:23:00.000-07:00

ex: http://localhost:3000/rabbit/list

when getting request above, the load sequence is as follows:

1. load rabbit_controller.rb

2. instantiate an object of class RabbitController

3. look in app/helpers for rabbit_helper.rb.

If found, the module RabbitHelper is mixed into RabbitController

4 look in app/models for rabbit.rb. If found, load it

define the models used in controller:

ex:

model :car, :clothes

define the observers used in controller:

ex:

observer :car_observer

define the model used in controller

flash

2008-05-08T22:16:00.003-07:00

the value stored in the flash in the first request is available in the second request.

After processing 2nd request, the value is removed from flash

main use:

error message

ex:

def test

flash[:note] = "error"

redirect_to :action=>test2

end

test2.html.erb

<%= @flash[:note] %>

session & cookie

2008-05-08T22:16:00.001-07:00

controller action, view tempelate, render

2008-05-08T22:03:00.000-07:00

controller裡定義的action(method)會對應到view下的templelate

例如index對應到index.html.erb

所以如果controller要做的action是index，

browser顯示的網頁即是index.html.erb

為何action是index，即顯示index.html.erb ?

一般在controller定義的action，

例如index，

預設都會呼叫如下的render 指令，

所以controller在做index action時，

即會顯示index.html.erb

render command:

ex:

render :template => “test/index”

顯示 view/test/index.html.erb

:template後接的path是相對於view

如果改成:file，之後的path是絕對路徑

如果render顯示的是另一個page，

改變的是顯示的內容，

URL還是原page的URL，

若要連URL一起改變，

要代用redirect_to

ex:

render :action=>”index”

顯示 index.html.erb

(注意render不會做action，只會顯示頁面，

若要做action，要用redirect_to)

ex:

render :text=> “hello”

顯示hello

:status

ex:

render :status=>404

html response的status

可以不定義action，但一定要定義顯示的頁面

例如index action沒定義，

但index.html.erb有定義，

則browser還是可以顯示正確的頁面。

the instance variable of the controller is available in the template

the template can access instance variable set in the controller action. Hence, rabbit's view can access dog's controller's instance variable if it is triggered from dog's action

form helper

2008-05-08T11:35:00.000-07:00

form_tag: 和model無關

ex:

<% form_tag do %>

<p><label for=”login”>Login</label>

<%= text_field_tag ‘login’ %></p>

<% end %>

1.如果form_tag後沒有接action，那麼action就是form目前所在的

頁面對應到的method

2存取使用者輸入的資料，例如param, such as params[:login], log對應

到text_filed_tag的值

ex:

<% form_tag :action=>'play' do %>

<p><label for=”login”>Login</label>

<%= text_field_tag 'car', ‘login’ %></p>

<% end %>

1. text_field_tag後接的car是model name，login是car的attribute

, the controller can access it using params[:car][:login]

submit_tag 後接的字串是submit button上的文字

form_for : 和model有關

ex:

<% form_for :person, @person,

:url => { :action => "create" } do |f| %>

<%= f.text_field :first_name %>

<%= f.text_field :last_name %>

<%= submit_tag 'Create' %>

<% end %>

對應的html

</form>

存取使用者輸入的資料:

以上面為例子，Person.new(params[:person] )

ex:

<% form_for :rabbit , url=>{ :controller=>:rabbit, :action=>create},

:html=> {:id=>’peter’ } do |t| %>

對應的html

text_field & text_field_tag

regular form helper is usually end with tag

model form helper is usually not end with tag

ex:

text_field :customer, :name

create customer in the action of controller:

@customer = Customer.new(params[:customer])

text_field:

hidden_field:

password_field:

text_area:

radio_button(:variable, :attribute, tag_value, options):

check_box:

select:

selection list

ex:

save & save!

2008-05-08T11:30:00.000-07:00

save object into database

save! will raise a exception if the save is not successful

save only return false when save is not successful

update_attributes, updat & update_all, save

2008-05-08T11:16:00.000-07:00

update column of table

update will change the state of object and database

update_attributes

ex:

rabbit.update_attributes( :name=> "peter", :age=> 13)

update

ex:

Rabbit.update( 5, :name=>"peter", :age=>13)

update rabbit with id =5

update_all:

Rabbit.update_all(:name=>"peter")

all rabbits' names become "peter"

use save:

ex:

rabbit.name="peter"

rabbit.save

use save to update database

find method in rails

2008-05-07T22:01:00.000-07:00

without dynamic find_by_all

@task = Task.find( :all, :conditions=> [‘complete= ?’ ,false] )

with dynamic find_by_all

@task = Task.find_all_by_complete(false)

without dynamic find_by

@task = Task.find( :first, :conditions=> [‘complete= ?’ ,false],

:order=>’created_at DESC’ )

with dynamic find_by

@task = Task.find_by_complete(false, :order=>’created_at DESC’)

find by id

find( params[:id], :conditions=>[“name=?”, “peter” ] )

find through association

ex:

project has many tasks

task belongs to project

without association:

@task = Task.find(:all, :conditions=> [ ‘proect_id=? AND complete =?’ , @project_id, false] )

with association:

@project = Project.find(params[:id])

@task = @project.tasks.find(:all, :conditions=>[‘complete=?’, false])

@task = @project.tasks.find_all_by_complete(false)

find method in model

將find method定義在model比較好

ex:

Task的model

def self.find_incompletet

find_all_by_complete(false, :order=>’created_at DESC’ )

end

注意: 此find method要定義成class method

到時候可呼叫 @project.tasks.find_incomplete

若定義成instance method，則會error

find_by_sql:

use sql syntax in the find_by_sql

pros: faster

ActionMailer & gmail

2008-05-07T08:03:00.000-07:00

use ActionMailer to send email ( with gmail)

ex:

require 'rubygems'

require 'action_mailer'

require 'smtp_tls'

class Emailer <>

def test_email(email_address, email_body)

recipients(email_address)

from "peter@gmail.com"

subject "This is a test e-mail"

body email_body

end

ActionMailer::Base.smtp_settings = {

:address => "smtp.gmail.com",

#25 ,465

:port => 587,

#:domain => "localhost.localdomain",

:authentication => :plain,

:user_name => "peter",

:password => "xxxxxx",

}

Emailer.deliver_test_email('jack@yahoo.com', 'this is a test email')

smtp_tls is for sending email from gmail

send by gmail in rails:

1. add smtp_tls.rb in configure directory

2. add require 'smtp_tls' in environment.rb

access table's column in the model

2008-05-07T07:37:00.000-07:00

ex:

the table rabbits has column name

the model rabbit can access name by self.name

before_create

2008-05-07T07:28:00.000-07:00

like before_filter, but before_create is used in the model

is executed when the record is created

filter

2008-05-07T07:05:00.000-07:00

define the actions to do before(after) some actions

two define syntaxes:

1. use method to define filter

2. use class to define filter

before_filter:

define the actions to do before some actions

ex:

before_filter :check

do check before any action.

If check return false, the action is not done

after_filter:

define the actions to do after some actions

filter & inheritance :

B extends A, then A's filter is done first, then B's filter is done

filter's scope:

only for some actions:

ex:

before_filter :check, :only=>:index

before_filter :check, :only=>[:index, :new]

not for some actions:

before_filter :check, :except=>:index

around_filter:

the combination of before_filter & after_filter

ex:

class TestFilter

def before(controller)

@name="peter"

end

def after(controller)

@name ="andy"

end

around filter TestFilter.new

mongrel

2008-05-06T22:10:00.000-07:00

a web server

faster than WEBrick

install:

sudo gem install mongrel

start:

mongrel_rails start

start options:

-d: run in background

-e: rails environment to run

stop:

mongrel_rails stop

restart:

mongrel_rails restart

link

2008-05-06T21:55:00.000-07:00

link to css

stylesheet_link_tag 'test'

test.css is in /public /stylesheets

link to image

image_tag 'test.jpg'

test.jpg is in /public/images

link to page

link_to "go to" , :controller=>"test", :action=>"index"

link to javascript:

javascript_indclude_tag :defaults

link to prototype, effects, dragdrop, controls, application in /public/javascripts

url_for:

generate url according to route.rb

ex:

url_for ( :controller=>"rabbit", :action=>jump )

--> http://localhost:3000/rabbit/jump

layout

2008-05-06T21:54:00.001-07:00

the layout for all website:

method 1:

use application.html.erb, it is the layout for all website

method 2:

ex:

define the layout test.html.erb

add following line to app/controllers/application.rb

layout "test"

yield:

render the template. The template is rendered at this location within layout

layout can access variable defined in the template

rails routing

2008-05-06T21:48:00.000-07:00

config/route.rb

set the page of webSite root:

map.root :controller => "test"

note: remember to remove /public/index.html

default route

map.connect ':controller/:action/:id'

map.connect ':controller/:action/:id.:format'

ex:

http://localhost:3000/test/apple/3.xml

test map to :controller, apple map to :action, 3 map to :id, xml map to :format

the parameter get from default route:

params[:controller], params[:action], params[:id]

set controller & action:

map.connect 'test/:var', :controller=>rabbit, :action=>jump

ex:

http://localhost:3000/test/apple

apple map to :var

:requirements

set the requirement the component must match

ex:

map.connect ":day", :requirements => { :day => /[0-3]?\d }

the pattern for remaining components in the URL ( not specify in the URL)

use * with a name

ex:

map.connect "*anything", :action=> "unknown_action"

named route:

replace map.connect with map.routeName,

replace url_for with routeName_url

ex:

map.run :controller=>"test", :action=>"run"

redirect_to (run_url)

link_to(" run" , run_url )

generate command, rails command, rake command, console

2008-05-06T21:39:00.000-07:00

rails:

rails -d mysql test

create files for rails project, using mysql

( default is sqlite)

generate:

script/generate controller rabbit index

create rabbit controller with index action, rabbit test, rabbit helper & index template in the rabbit view

rake:

rake db:migrate

create the table in the database based on the migration file

script/console:

-s: Any modifications you make will be rolled back on exit

erube

2008-05-06T08:40:00.000-07:00

deal with the file includes html & ruby code

install:

get eruby from http://www.modruby.org/en/index.rbx/eruby/download.html

set link:

sudo ln -s /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/eruby /usr/local/bin/eruby

combine apache & erube:

set link:

ln -s /usr/local/bin/eruby /Library/WebServer/CGI-Executables/eruby

edit /etc/apache2/httpd.conf

(1) red part

AllowOverride None

Options FollowSymLinks

(2) add following to

AddHandler rubypage .erb .rhtml

Action rubypage /cgi-bin/eruby

run eruby:

eruby test.html.erb

erb

cgi

2008-05-06T07:06:00.000-07:00

require 'cgi'

cgi's method name equals the tag it create

Hence, cgi.h1 create h1 tag

use + to combine the same level tag

ex:

cgi = CGI.new('html4')

cgi.out do

cgi.html do

cgi.head do

"test head"

end +

cgi.body do

cgi.h1 { "hello" }

end

--->

<HTML><HEAD>test head </HEAD><BODY><H1>hello</H1></BODY></HTML>

cgi.params:

represent query string

ex:

http://localhost/cig-bin/test.cgi?name=peter&age=3

cgi.params = { 'name'=>'peter', 'age'=>'3' }

send

2008-05-05T21:47:00.000-07:00

dynamically call a method with unknown name

ex:

def test_rabbit(name)

puts name

}

a="rabbit"

send("test_#{a}", "peter")

----> peter

1st parameter is method name, second parameter is parameter

usage: get method from user input

note:

some_object.send( function_name, args ) is the same as

some_object.function_name(args )

show message with debug

2008-05-04T08:37:00.000-07:00

write to stand error

ex:

warn "error" if ($DEBUG)

enable $DEBUG

ruby -d

xml library

2008-05-04T07:30:00.000-07:00

require 'rexml/document'

<=>

2008-05-04T02:56:00.001-07:00

ex:

3 <=> 3

---> 0

3 <=> 4

---> -1

4 <=> 3

---> 1

test

2008-05-03T07:29:00.000-07:00

require 'test/unit'

assert_equal

if two parameter are equal, return true

ex:

assert_equal("dd", "ee")

ri command

2008-05-03T07:24:00.001-07:00

read the information about ruby API

ex:

ri Test::Unit

alias

2008-05-03T07:16:00.001-07:00

define another method name

ex:

alias :puts_2 :puts

puts_2 “ hello”

---> “hello”

system

2008-05-03T07:07:00.000-07:00

call extern program

ex:

System( “ls”)

method naming ( end with ? or ! )

2008-05-03T06:57:00.000-07:00

method that returns true or false ends with ?

ex:

empty?

method that changes the state of the object ends with!

ex:

save!

built-in methods with !

upcase!, chomp!, sort!, reverse!

change value to string( interpolation)

2008-05-03T06:56:00.001-07:00

use “#{ }”

ex:

a= 123

b= “#{a}”+ “4”

---> b= “1234”

file methods

2008-05-03T06:48:00.000-07:00

read a file:

input_file =File.new (filename, ‘r’)

write a file:

output_file= File.new( filename, ‘w’)

‘w+’:

read and write. When creating the file, the old file is overwritten

'a':

append

read:

return the content of the file in the string

readlines:

output_file.readlines()

return an array with each line of the file

puts:

output_file.puts(“hello”)

write “hello” to output_file

close:

output_file.close()

close the file

show the files and directories under directory:

ex:

Dir.open("Desktop").entries

---> [ "." , "..", "test.c", "book"]

directory?

ex:

File.directory?("test")

extname:

ex:

File.extname("test.exe")

--> ".exe"

environment variable

2008-05-03T06:44:00.000-07:00

ENV[‘HOME’] (for unix-like)

ENV[‘HOMEDRIVE’]+ ENV[‘HOMEPATH’] (for windows)

return the path of home directory

ex:

on my mac , output is “/Users/Pan”

ARGV

the parameter to the ruby program

ex:

ruby test.rb 123

ARGV[0] is 123

comment

2008-05-03T06:34:00.000-07:00

start with #

=begin & =end

use in multiple-line

if , else, elsif, unless

2008-05-03T06:28:00.000-07:00

if and else:
ex:
if a==3
puts “a==3”
else
puts “a!=3”
end

elsif

use elsif, not elseif

unless

if ! (x==1)

equals

unless x==1

plugin install

2008-05-03T01:06:00.000-07:00

install for ruby

remote install:

ex:

gem install sqlite3-Ruby

local install:

ex:

1. get gem file from http://rubyforge.org

2. gem install scruffy-0.2.2.gem

( in the directory with scruffy-0.2.2.gem)

install for rails project

remote install:

ex:

script/plugin install http://svn.techno-weenie.net/projects/plugins/acts_as_authenticated/

local install:

1. 用svn抓plugin下來

ex:

svn checkout http://svn.techno-weenie.net/projects/plugins/acts_as_authenticated/

2. 將plugin放到rails project下的vendor/plugins/

textmate & rails 2.0

2008-05-02T20:03:00.000-07:00

install rails 2.0 bundle

1. download rails 2.0 bundle rails 2.0 bundle

2. move rails 2.0 bundle to Library/Application Support/TextMate/Bundles,

rename the bundle as Ruby on Rails.tmbundle

3. reload bundle in textmate

4. mv Builder.rb Builder.rb.off

in Applications/TextMate.app/Contents/SharedSupport/Support/lib

textmate shortcut

2008-05-02T10:07:00.000-07:00

select word:

ctrl + w

show bundle list

ctrl + esc

select bundle item:

ctrl + command + t

show bundle editor:

ctrl + option+ command + b

ToDo bundle:

show ToDo list

ctrl + shift + t

Define TODO: , FIXME: , CHANGED: in the comment of the file.

Then show ToDo list will find there lines in the files

html bundle:

insert open & close tag with current word

ctrl + <

ex:

enter head, then with this short cut, it becomes

ex:

enter this short cut, then enter abc, it becomes

wrap selection in open & close tag

ctrl + shift + w

ex:

enter hello, then enter this short cut, then enter head, it becomes hello

tab completion :

1. head:

head+ meta + title

2. style:

3. script:

4. doctype:

insert a link(with the word in the clipboard)

ctrl + shift + L

webpage preview:

ctrl + option+ command + p

ruby bundle:

run ruby program

command + r

# => mark

add # => mark

# + tab

execute the line with # => mark

ctrl + shift + command + e

find doc about the word

ctrl + h

tab completion :

1. cla :

for class

2. def :

for method

3. r , w, rw

for attr_reader(), attr_writer(), attr_accessor()

4. while

5. if

6. inj:

for inject

7. ea:

for each

8. tim:

for times

9. sorb:

for sort_by

10. eawi:

each_with_index

rubyOnRails bundel:

activate rubyOnRails bundle:

ctrl + option + shift + r + 3

params completion:

ctrl + p

session completion:

ctrl + j

call generate script:

ctrl + | + 1

tab completion:

for model:

1. mccc

for model create column continue

2. t.

提示column type

3. mcol

create column

visor : terminal access

2008-05-02T09:38:00.000-07:00

1. install SIMBL

2. install visor

provides a systemwide terminal window accessible via a hotkey

my hot key: command + 1

date and time method

2008-05-02T01:50:00.000-07:00

require 'date'

require 'time'

Time.now or Time.new

--> Fri May 02 16:50:08 +0800 2008

Time.now.strftime('%Y-%m-%d')

--> "2008-05-02"

SECOND_IN_A_DAY

兩個時間相減得到的單位是秒

Date.today:

%Y, %y: year

%b, %B: month

%m : month(number)

%d, %e: day of month

%a, %A: dat name( such as Tue)

%H, %I: hour

%M: minute

%S: second

%c: equals "%a %b %d %H:%M:%S %Y"

%x: equals "%m/%d/%y"

block and yield

2008-05-01T09:51:00.000-07:00

yield:

run what block defines

ex:

def test(*args, &block)

yield(*args)

end

test("hello"){ |i| puts i }

---> hello

note:

yield(*args) = block.call(*args)

when defining a method that receives blocks,

there are two ways

(1) define method with block arguments

ex:

def test( &block)

end

(2)define method without block arguments

ex:

def test

end

pass arguments to blocks

in the method definition, call yield with arguemtns

ex:

yield (a, b, c)

in the block, use | | to receive arguments

ex:

| a, b, c|

return value from call block

the return value is last expression evaluated in block

ex:

in the method definition

a= yield

here doc

2008-05-01T09:26:00.001-07:00

build up a long string

ex:

NAME= <<END_MY_STRING

hello

how are you

END_MY_STRING

puts NAME

---> hello

how are you

required, optional, default-valued parameters

2008-05-01T07:31:00.001-07:00

required parameter:

def test1( name)

end

default value parameter

def test2(name=”peter”)

end

呼叫test2時，若是沒傳參數，則name=”peter”,

若是傳參數”andy”，則name=”andy”

optional parameter

use *

ex:

def test(*abc)

end

abc可接受多個參數，以array表示

例如呼叫test(1,2)

則p abc 印出 [1, 2]

note: optional parameter must be last parameter of the method

block, proc and &

2008-05-01T07:14:00.000-07:00

call method with block parameter:

two syntaxes:

1. { }

this is useful for one line

2. do end

this is useful for multiple line

ex:

["a", "b"].each do |i|

puts "#{i}"

end

the element between | | refers to each element in the array

define a method with block parameter

use &

ex:

class Array

def test( &arg)

find_all( &arg)

end

pass proc parameter to a method received block

ex:

a=lambda{ puts "abc"}

test(&a)

lambda and proc

2008-05-01T05:20:00.000-07:00

lambda:

parameter: block

return: an instance of class Proc

Proc:

procedure

method:

call:

tell proc to do sth

ex:

test = lambda { |i| i + 1 }

test.call(2)

--> 3

the method to pass parameters

1. test.call(2)

2. test[2]

another method to create Proc:

Proc.new { }

IDE

2008-05-01T01:19:00.000-07:00

textmate :

mac, not free

aptana studio:

mac & windows, free

include RadRails

3rdRail:

mac & windows, free

NetBeans:

mac & windows, free

web api

2008-04-30T10:28:00.001-07:00

open-uri

get date from URI

add require 'open-uri' in the program

YAML

2008-04-30T10:18:00.000-07:00

load:

ex:

YAML.load(File.open("test.yaml") )

return the content in test.yaml

such as "name: peter" return 'name'=>'peter'

dump:

write to YAML file

ex:

File.open("test.yaml", w) { |output| YAML.dump(names, output) }

error handling: rescue & raise

2008-04-30T10:00:00.001-07:00

handle exception:

ex:

begin

puts 1/0

rescue

puts "error"

end

---> "error"

rescue can for specific exception:

ex:

begin

puts 1/0

rescue ZeroDivisionError

puts "error"

end

rescue for method

ex:

def test

puts "test"

rescue

puts "rescue"

end

raise

raise exception

ex:

def test

raise ArgumentError, "argument error"

end

the second argument is the message printed

get the exception

ex:

rescue ArgumentError => e

e is the exception

define exception

ex:

class TestException <>

end

range

2008-04-30T08:11:00.000-07:00

ex:

(‘A’..’Z’)

ex:

0..9

define class

2008-04-30T07:53:00.000-07:00

ex:

class Rabbit

def initialize( name)

@name = name

end

def run

puts “run”

end

initialize:

this method is called when the object is created

this is a private method. Hence, when using new to create object, the new method will call initialize

instance variable:

the variable that starts with @ is instance variable

naming convention:

class name: CuteRabbit

file name : cute_rabbit.rb

private:

the method is private

define methods after private

ex:

private

def test

end

protected:

the method is protected

modify existing class

ex: the Array is built-in class.

class Array

def test

end

now the Array has new method test

class variable:

the variable that starts with @@ is class variable

class method:

ex:

def self.test

end

inheritance:

ex:

class Circle < Shape

end

if class Square is defined inside class Shape, you must access Square with

Shape::Square outside class Shape

ex:

class Test < Shape::Square

end

constant in the class

if TEST is the constant of class Rabbit,

we can access Test using Rabbit::Test

constant

2008-04-30T07:51:00.001-07:00

use capital letter

ex:

Apple, Rabbit

access constant define in class

ex:

Name is defined in the class Rabbit

Rabbit::Name

hash

2008-04-30T07:49:00.001-07:00

hash is declared inside { }

ex:

animal= {

:one=> “dog”,

:two=>”rabbit”

}

說明:

animal[:one] = “dog”

animal[:two]=”rabbit”

ex:

animal= {

:one=>[‘v’, ‘version’ ]

}

CONSTANT is often defined as hash

ex:

OPTIONS={

:command=>[‘r’, ‘run’]

}

keys:

return the keys of hash in the array

ex:

{ :a=>”name”, :b=>”age”}.keys

--> [ :a, :b ]

values:

return the values of hash in the array

ex:

{ :name=>"peter"}.values

---> ["peter"]

values_at

get multiple element

ex:

{ :a=>"a", :b=>"b", :c=>"c"}.values_at(:a,:b)

---> ["a", "b"]

has_key? :

ex:

{:a=>"a"}.has_key?(:a)

---> true

sort_by:

由小排到大

ex:

a={ :c=>"C", :b=>"B" }

a.keys.sort_by{ |i| a[i] }

---> [:b, :c]

ex:

sort_by{ |a, b| }

sort according to a first, according to b in case of a tie

merge:

ex:

{ :a=>"a", :b=>"b"}.merge( {:a=>"c", :d=>"d" } )

--> { :a=>"c", :d=>"d", :b=>"b" }

each_key:

ex:

c= { :a=>"aa", :b=>"bb"}

{ :a=>"aa", :b=>"bb"}.each_key { |i| puts c[i] }

--> aa

each_pair:

{ "name"=>"peter"}.each_pair do |i,j|

puts i+ " "+ j

end

---> name peter

sort:

return nested array

default(without pass block parameter) :

ascending order & compare hash's value

ex:

{ "b"=>1, "a"=>2}.sort

--> [ ["b", 1], ["a", 2] ]

Hash.new(0)

set default value of hash for nonexistent keys, the key is still nonexistent

ex:

a =Hash.new(0)

a[2]

---> 0

set default value of hash for nonexistent keys, the key is added

ex:

a=Hash.new { |hash, key| hash[key]=0 }

RDoc

2008-04-30T07:48:00.000-07:00

=begin rdoc

RDoc comments

=end

allow HTML-like tagging

each, each_with_index, map

2008-04-30T07:47:00.000-07:00

each:

accept block parameter that describe what to do with each element of array or hash

ex:

[“A”, “B”].each do |i|

puts “#{i}”

end

---> A

each_index:

ex:

["A", "B"].each_index do |i|

puts "#{i}"

end

each_with_index:

ex:

['a','b','c'].each_with_index do |content, index|

puts "#{content}#{index}"

end

---> a0

map:

v.s each: different in return

it return the new value, each return original value

ex:

[1,2,3].map{ |i| i*2 }

--->[2,4,6]

map! will change content of caller

array

2008-04-30T07:46:00.000-07:00

enclosed with [ ]

can contain elements with different classes

add element to array:

use <<

ex:

a=[]

a <<>

array adding
ex:
[“test1”] + [“test2”]
--> [ “test1”, “test2” ]

use concat:

ex:

[1,2].concat([3,4])

--> [1,2,3,4]

concat modifies original array

<<:

add element to array

ex:

a=[1,2]

a<<3

---> [1,2,3]

new:

ex:

Array.new(3, "a")

create a three element array ,with each initialized to "a"

a=0

Array.new(3) { a=a+1 }

create a three element array , [1,2,3]

get more than one elements

ex:

a=[1,2,3,4,5]

a[3,2]

---> [4,5]

sort_by

accept block argument

ex:

sort_by{ rand }

sort randomly

join:

[“a”, “b”, “c”].join(‘2’)

--> “a2b2c”

push:

add an element to the end of the array

pop:

remove last element

include:

ex:

[1, 2, 3].include?(1)

---> true

uniq:

ex:

["ab", "c","ab"].uniq

--->["ab", "c"]

multiplication:

ex:

[1,2]*2

--> [1,2, 1,2]

detect:

find the first element that match condition in the array

ex:

[1 , 2, 3].detect { | i | i>2 }

--> 3

find:

find first element that matches

find_all:

find all elements that match condition in the array

ex:

[1,2,3].find_all{ |i| i>1 }

--> [2, 3]

array intersection:

use &

ex:

[1,2,3] & [2,3]

--> [2,3]

%w[a b]

--> ["a", "b"]

sort:

ex:

c=[ [1, 2], [3, 1] ]

c.sort{ |a, b| a[0]<=>b[0] }

--> [ [1,2], [3, 1] ]

c.sort{ |a, b| b[0]<=>a[0] }

--> [[3, 1], [1, 2]]

c.sort{ |a, b| a[1]<=>b[1] }

--> [[3, 1], [1, 2]]

a[0] <=> b[0] compare first element of nested array in ascending order

a[1] <=> b[1] compare second element of nested array in ascending order

b[0] <=> b[1] compare first element of nested array in descending order

unshift:

add an element to the beginning of the array

shift:

remove the first element

zip:

ex:

[1,2].zip([3,4])

--> [ [1,3], [2,4] ]

flatten:

ex:

[1,2, [3,4] ].flatten

--> [1,2,3,4]

reject:

ex:

[1,2,3].reject { |item| item>2 }

---> [1,2]

replace, reverse:

each, each_with_index

include?, empty?, any?, all?

ex:

[1,2,3].any?{ | k| k>2 }

---> true

index:

return the first element equals to parameter

ex:

["a", "b", "c"].index( "b")

---> 1

index with integer <0

count from right

ex:

a= [1, 2, 3]

a[-1]

---> 3

compact:

remove nil element from the array

regular expression

2008-04-30T07:40:00.000-07:00

use / / to include regular expression

ex:

/a/

test regular expression match:

use =~

ex:

“hello”=~ /el?/

---> 1

? :

zero or more occurrence

one or more occurrence

\W:

any whitespace

\{X}:

ex:

a{3}

--> three a

\d:

any digit

treat the special character after it as normal character

^ :

anchor for the beginning of a line

anchor for the end of a line

match 0 or more occurrences of preceding character

Regexp.new:

ex:

Regexp.new("test")

---> /test/

string method

2008-04-30T07:37:00.000-07:00

crate string array

ex:

%w[AB CD]

---> [“AB”, “CD”]

gsub & gsub!:

global substitution

ex:

"hello".gsub("e","a")

---> "hallo"

gsub! will change original string

gsub & sub:

gsub change every match, sub only change first match

ex:

"helleo".gsub("e","a")

--> "hallao"

"helleo".sub("e","a")

--> "halleo"

sprintf:

ex:

sprintf(“%2d”, 3)

--> “ 3”

inject:

ex:

[1, 2,3].inject(10) { | sum, number| sum=sum+number }

--> 16

inject初始sum為10，

然後10+1=11

11+2=13

13+3=16

chomp:

remove the newline character

chop:

remove last character

grep:

ex:

["test", "b", "testa", "test"].grep("test")

--->["test", "test"]

split:

ex:

“hello”.split(‘e’)

--->["h", "llo"]

ex:

a, b= "hello".split('e')

--> a= "h", b="llo"

chr:

a= "abcde"

a[0].chr

--> "a"

strip:

return a copy with leading and tailing whitespace removed

lstrip & rstrip

removing left or right whitespace

%q :

create string, single-quoted

ex:

%q (abc)

---> "abc"

%Q:

create string, double-quoted

\ :

use \ to escape:

ex:

puts "abc\"de"

---> abc"de

<<:

add string(modify original string)

ex:

a="test"

a<< "abc:

puts a

--> testabc

replace:

ex:

a="test"

a.replace("abc")

puts a

---> abc

reverse, downcase, upcase, capitalize, swapcase

substring:

ex:

"abcde"[2,2]

---> "cd"

a="abcde"

a[2,2]="gg"

---> "abgge"

succ:

ex:

"abc".succ

--> "abb"

format string

ex:

"%.2f"%3.333

--->"3.33"

module

2008-04-30T07:33:00.000-07:00

module is like class, but it can not be instantiated

support methods for other class

use include to include module

a class can only have inherit from one class, but it can mix in more than one mouels

ex:

module Animal

def test

ned

end

class Rabbit

include Animal

def run

test

end

if a class include two modules, M1 & M2( M2 is included last),

M1 & M2 both have method test

When the object of the class calls method test,

it will call M2's test

require

2008-04-30T07:30:00.000-07:00

use external file

ex:

require 'test'

t= Test.new

Test class is defined in another file( test.rb)

math methods

2008-04-30T06:37:00.000-07:00

abs:

ex:

-3.abs

--> 3

zero?

tell if the number is zero

ex:

3.zero?

--> false

rand:

ex:

rand(100)

return an random integer from 0 to 99

round:

ex:

3.1.round

--> 3

3.5.round

--->4

useful utilities (irb, ruby)

2008-04-30T04:29:00.001-07:00

irb:

a shell to run ruby

irb -r test.rb

include the content of test.rb, r is require

ruby:

-w:

turn warnings on for your script

-e:

execute the code in ' '

ex:

ruby -e 'puts "hello" '

---> hello

-r:

require some files

-rdebug:

debug program,

step command: run next instruction

-r profile:

test performance