railscasts.net的相关内容 - tianlu1677/tianlu1677.github.io GitHub Wiki
主要简单记录一下，rails的技巧。
class ApplicationController < ActionController::Base
def current_user
@current_user ||= User.find(session[:user_id])
end
end这里主要是把存在session里面的user_id取出来，然后赋值给实例变量，这样在view 和 controller 都可以访问到，同时 ||= 实现了避免重复赋值的问题。
def self.all_names
find(:all).collect(&:name)
end##8 Layouts and content_for
<% content_for :not_authorized do %>
alert('You are not authorized to do that!')
<% end %>
<%= content_for :not_authorized if current_user.nil? %>
content_for?(name) # 用于判断当前 页面是否有name的content_for 方法不要把model存储来session里面。主要是会产生两个问题，每次调用的时候都会产生请求。二是，修改时候并不会走validate验证。所以只需要存储关键字段，用到的时候查询读取。
##16 Virtual Attributes
class User < ActiveRecord::Base
# Getter
def full_name
[first_name, last_name].join(' ')
end
# Setter
def full_name=(name)
split = name.split(' ', 2)
self.first_name = split.first
self.last_name = split.last
end
end把一个字段切割长两个来显示。但在现实中尽量不要采用这种方式，ugly！
##22 Eager Loading rails 4 中已经解决这个问题
需要具体报错信息，一般都会显示在第一行。
tasks = Task.find(:conditions=> [ "name LIKE ?", "%#{params[:query]}%" ]还里还需要了解一下rails的安全机制
需要对用户输入的内容进行转义
##28 29 分组
in_groups_of(number, fill_with = nil)
in_groups(number, fill_with = nil)
%w(1 2 3 4 5 6 7 8 9 10).in_groups(3, ' ') {|group| p group}
["1", "2", "3", "4"]
["5", "6", "7", " "]
["8", "9", "10", " "]
(1..6).group_by { |i| i%3 } #=> {0=>[3, 6], 1=>[1, 4], 2=>[2, 5]}module ApplicationHelper
def title(page_title)
content_for(:title) { page_title }
end
end
<title>ASCIIcasts - <%= yield :title %></title>#17 使用 check_box_tag 标签来实现多选
<% for category in Category.find(:all) %>
<div>
<%= check_box_tag "product[category_ids][]", category.id, @product.categories.include?(category) %>
<%= category.name %>
</div>
<% end %>Date.current
DateTime.now
DateTime.current
DaTeTime.now.at_beginning_of_day
DaTeTime.now.at_beginning_of_hour
DaTeTime.now.at_beginning_of_minute
DaTeTime.now.at_end_of_day
DaTeTime.now.at_end_of_hour
DaTeTime.now.at_end_of_minute
DaTeTime.now.at_middle_of_day
DaTeTime.now.at_midnight
DaTeTime.now.to_i
atetime = DateTime.civil(2007, 12, 4, 0, 0, 0, 0) # => Tue, 04 Dec 2007 00:00:00 +0000
datetime.to_formatted_s(:db) # => "2007-12-04 00:00:00"
datetime.to_s(:db) # => "2007-12-04 00:00:00"
datetime.to_s(:number) # => "20071204000000"
datetime.to_formatted_s(:short) # => "04 Dec 00:00"
datetime.to_formatted_s(:long) # => "December 04, 2007 00:00"
datetime.to_formatted_s(:long_ordinal) # => "December 4th, 2007 00:00"
datetime.to_formatted_s(:rfc822) # => "Tue, 04 Dec 2007 00:00:00 +0000"
datetime.to_formatted_s(:iso8601) # => "2007-12-04T00:00:00+00:00"
#42 用with_options 来消除冗余代码
with_options :if => :should_validate_password? do |user|
user.validates_presence_of :password
user.validates_confirmation_of :password
user.validates_format_of :password, :with => /^[^\s]+$/
end
attr_accessor :updating_password
def should_validate_password?
updating_password || new_record?
end
#46 变化的路由
pluralize
#56 在输出的时候，显示写的logger 信息
require 'logger'
logger = Logger.new(STDOUT)
logger.level = Logger::WARN
logger.debug("Created logger")
logger.info("Program started")
logger.warn("Nothing to do!")
path = "a_non_existent_file"
begin
File.foreach(path) do |line|
unless line =~ /^(\w+) = (.*)$/
logger.error("Line in wrong format: #{line.chomp}")
end
end
rescue => err
logger.fatal("Caught exception; exiting")
logger.fatal(err)
end
#57 在选择的时候，再新建，更加友好