rails view session layout

#208 erb-blocks

简介：在erb中使用blocks,可以为 html，封装逻辑

module ApplicationHelper
  def admin_area(&block)
    content_tag(:div, :class => "admin", &block) if admin?
  end
  
  def admin?
    true
  end
end

#234 simple_form

<%= simple_form_for @product do |f| %>
  <%= f.error_messages %>
  <%= f.input :name %>
  <%= f.input :price, :hint => "prices should be in USD" %>
  <%= f.input :released_on %>
  <%= f.association :category, :include_blank => false %>
  <%= f.input :rating, :collection => 1..5, :as => :radio %>
  <%= f.input :discontinued %>
  <%= f.button :submit %>
<% end %>

#132 helpers-outside-views

1、在 model 在使用helper
def description
  "This category has #{helpers.pluralize(products.count, 'product')}."
end

def helpers
  ActionController::Base.helpers
end
2、在controller中使用helper
flash[:notice] = "Successfully created #{@template.link_to('product', @product)}."

#7 layout

Layouts are view files that define the code that surrounds a template. They can be shared across many actions and controllers.
1、默认
全局 applicateion.html.erb
controller相关 layout project.html.erb
 
2、动态指定
class ProjectsController < ApplicationController
  layout :user_layout
  protected
   def user_layout
     if current_user.admin?
       "admin"
     else
       "application"
     end
   end
。。。
end 

3、直接指定
class ProjectsController < ApplicationController
  layout "admin"

  def index
    @projects = Project.find(:all)
    render :layout => 'projects'
  end
  
  render :layout => false
  
end

#125 dynamic-layouts

简介：实现动态布局


application.rb
def load_blog
  @current_blog = Blog.find_by_subdomain(current_subdomain)
  if @current_blog.nil?
    flash[:error] = "Blog invalid"
    redirect_to root_url
  else
    self.class.layout(@current_blog.layout_name || 'application')
  end
end
blogs_controller
1、使用application中的 load_blog
before_filter :load_blog, :only => :show

2、简单地在controller中指定
layout :blog_layout 
   
def blog_layout
"plain"    
@current_blog.layout_name
end

3、用户自定义
erviroment.rb
config.gem 'liquid'
custom.html.erb
<%= Liquid::Template.parse(@current_blog.custom_layout_content).
      render('page_content' => yield, 'page_title' => yield(:title)) 

     

# 8 Layouts and content_for

If you want to change something in the layout on a per-template basis, content_for is your answer! 
This allows templates to specify view code that can be placed anywhere in a layout.
通常，是template中的内容，通过yeild,填充到 layout中
也可以，tempate中的内容，能过content_for :title 转给 layout用，办法是 yield :title


example
template这个储存
<% content_for :head do %>
  <%= stylesheet_link_tag 'projects' %>
<% end %>
layouts中这个接收
yield :title

#30 Pretty Page Title

Using a Helper Method

module ApplicationHelper
  def title(page_title)
    content_for(:title) { page_title }
  end
end

template
<% title "Recent Episodes" %>

layout
<title><%= yield (:title) || "default page" %></title>