RailsCasts 视频笔记

观看http://www.railscasts.com/中的视频时记得笔记，只有我自己才能看的懂
1

class ProjectsController < ApplicationController
	def show
		@project = Project.find(param[:id])
		@tasks = Task.find(:all,:conditions=>['project_id=? and complete=?',@project.id,false])
		@tasks = @project.task.find(:all,:conditons => ['complete = ?',false])
		@tasks = @project.tasks.find_all_by_complete(false)
	end
end

2
layout 查找模板的顺序为先在与Controller名字相同的模板，如果没有找到，就找application.rhtml模板。

layout可以指向一个方法。这样就可以根据条件来选择模板。
如：

  layout :user_layout
  ....
  privated
  
  def user_layout
  	if true
  	   "admin"
    else
       "application"
    end
  end

 
还可以为action指定特定的layout。
如：

   def index
   	@project = Project.find(:all)
   	render :layout => 'admin'
   	#render :layout => false 不指定模板
   end

  
3
filter_parameter_logging "password"
这样就过滤了password的值，是它不在日志中显示。保护密码


4

Task.sum(:priority)
=>SELECT sum(priority) AS sum_priority FROM tasks

Task.sum(:priority,:conditions => 'complete=0')
=>SELECT sum(priority) AS sum_priority FROM tasks WHERE (complete=0)

Task.maximum(:priority)
=>SELECT max(priority) AS max_priority FROM tasks

Task.minimum(:priority)
=>SELECT min(:priority) AS min_priority FROM tasks

p=Project.find(:first)
=>SELECT * FROM projects LIMIT 1

p.tasks.sum(:priority)
=>SELECT sum(priority) AS sum_priority FROM tasks WHERE (tasks.project_id=1)

p.tasks.sum(:priority,:conditions => 'complete=0')
=>SELECT sum(priority) AS sum_priority FROM tasks WHERE (tasks.project_id=1) AND (complete=0)

5

Task.count(:all,:conditions => ["complete=? and priority=?",false,3])
=>SELECT count(*) AS count_all FROM tasks WHERE (complete=0 and priority=3)

Task.count(:all,:conditions => ["complete=? and priority=?",false,nil])
=>SELECT count(*) AS count_all FROM tasks WHERE (complete=0 and priority=NULL)

Task.count(:all,:conditions => ["complete=? and priority IS ?",false,nil])
=>SELECT count(*) AS count_all FROM tasks WHERE (complete=0 and priority IS NULL)

Task.count(:all,:conditions => ["complete=? and priority IS ?",false,[1,3]])
=>会报错！

Task.count(:all,:conditions => ["complete=? and priority in (?)",false,[1,3]])
=>SELECT count(*) AS count_all FROM tasks WHERE (complete=0 and priority in(1,3))

Task.count(:all,:conditions => ["complete=? and priority in (?)",false,[1..3]])
=>SELECT count(*) AS count_all FROM tasks WHERE (complete=0 and priority in(1,2,3))

Task.count(:all,:conditions => {:complete =>false, :priority => 1})
=>Task count(*) AS count_all FROM tasks WHERE (tasks.'priority' = 1 AND tasks.'complete' = 1)

Task.count(:all,:conditions => {:complete =>false, :priority => nil})
=>Task count(*) AS count_all FROM tasks WHERE (tasks.'priority' IS NULL AND tasks.'complete' = 1)

Task.count(:all,:conditions => {:complete =>false, :priority => [1,3]})
=>Task count(*) AS count_all FROM tasks WHERE (tasks.'priority' IN (1,3) AND tasks.'complete' = 1)

Task.count(:all,:conditions => {:complete =>false, :priority => 1..3})
=>Task count(*) AS count_all FROM tasks WHERE (tasks.'priority' BETWEEN 1 AND 3 AND tasks.'complete' = 1)

Task.find_all_by_priority(1..3)
=>SELECT * FROM tasks WHERE (tasks.'priority' BETWEEN 1 AND 3 AND)

6 动态find查询

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

7

<% flash.each do |key,msg| %>
  <%= content_tag :div,msg,:id =>　key %>  
<% end %>

8 避免n+1查询

@tasks = Task.find(:all, :include => [:project,{:comments => :user}])

9

<% pluralize project.tasks.size, 'task' %>
def self.up
  add_column :projects,:tasks_count,:integer,:default => 0
  
  Project.reset_column_information
  Project.find(:all).each do |p|
    p.update_attributes :tasks_count,p.tasks.length
  end
end

10 group_by

def index
	@tasks = Task.find(:all, :order => 'due_at,id',:limit => 50)
	@task_months = @task.group_by {|t| t.due_at.beginning_of_month}
end

<% @task_months.each do |month, tasks| %>
	<h2><%= month.strftime('%B') %></h2>
	<% for task in tasks %>
	<div class="task">
		<strong><%= task.name %></strong>
		due on <%= task.due_at.to_date.to_s(:long) %>
	</div>
  <% end %>
<% end %>
或
<% @task_months.keys.sort.each do |month| %>
	<h2><%= month.strftime('%B') %></h2>
	<% for task in @task_months[month] %>
	<div class="task">
		<strong><%= task.name %></strong>
		due on <%= task.due_at.to_date.to_s(:long) %>
	</div>
  <% end %>
<% end %>

11 日期的格式化
在environment.rb中添加移行
Time::DATE_FORMATS[:due_time] = "due ata %B %d on %I:%M %P"
这样就可以使用了
<%= task.due_at.to_s(:due_time) %>


12 定制错误消息到error里

def due_at_string
	due_at.to_s(:db)
end

def due_at_string=(due_at_str)
	self.due_at = Time.parse(due_at_str)
rescue ArgumentError
	@due_at_invaild = true
end

def validate
	errors.add(:due_at,"不合格的日期格式") if @due_at_invaild
end

13
map.home '',:controller = 'projects', :action=>'index'
===
home_path
home_url
---------------------------------------------------------
map.task_archive 'tasks/:year/:month',:controller = 'projects', :action=>'archive'
===
task_archive_path(2007,5)
task_archive_path(:year=>2007,:month=5)