the data controller can access

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

verification

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

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")

group controllers into module

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

session & cookie

save & save!

save object into database

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

save only return false when save is not successful 

filter

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

end

around filter  TestFilter.new

link

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