ruby on rails 随记

learn from
codecademy

rails new myapp

bundle install

rails generate controller mycontroller

rails generate model mymodl

rake db:migrate   updates the database with the new messages data model

rake db:seed  seeds the database with sample data from db/seeds.rb

Ruby on Rails defines seven standard controller actions can be used to do common things such as display and modify data.



If you want to create routes for all seven actions in your app, you can add aresource
route to your routes file. This resource route below maps URLs to the Messages controller's seven actions (

index

, 

show

, 

new

, 

create

, 

edit

,

update

,
and 

destroy

):

resources :messages

If you only want to create routes for specific actions, you can use 

:only

 to
fine 

tune the resource route. This line maps URLs only to the Message controller's

index

 and 

show

 actions.

resources :messages, only: [:index, :show]

has_many
:destinations

 denotes that a single Tag can have multiple Destinations.

belongs_to
:tag

 denotes that each Destination belongs to a single Tag.

Open the migration file in db/migrate/ for the tags table, and add the following columns:

a 

string

 column
called 

title

a 

string

 column
called 

image

Next in the migration file for the destinations table, add the following columns:

a 

string

 column
called 

name

a 

string

 column
called 

image

a 

string

 column
called 

description

the line 

t.references
:tag

def show

    @tag = Tag.find(params[:id])

    @destinations = @tag.destinations

  end

The 

@destinations
= @tag.destinations

 retrieves all the destinations that belong to the tag, and stores them in 

@destinations

 def update

    @destination = Destination.find(params[:id])

    if @destination.update_attributes(destination_params)

      redirect_to(:action => 'show', :id => @destination.id)

      else

      render "edit"

    end

  end

  

  private 

  def destination_params

  params.require(:destination).permit(:name, :description)

    end