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Ruby的25个编程细节(技巧、实用代码段)

  • 时间:2022-05-15 19:30 编辑: 来源: 阅读:
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摘要:Ruby的25个编程细节(技巧、实用代码段)
[b]1.try 永远不会抛出异常 在 没有的时候 返回 nil [/b]
[u]复制代码[/u] 代码如下:
province_id = Province.find_by_name(prov).try(:id) 
[b]2.find(:first, :condotions) 方法 不言而与[/b]
[u]复制代码[/u] 代码如下:
mobile_info = MobileInfo.find(:first, :conditions => ["mobile_num = ? ", mobile_num.to_i]) 
[b]3.find(:all, :select, :conditions)[/b]
[u]复制代码[/u] 代码如下:
support_amount_a = ProvinceMerchantChangeValue.find(:all, :select => "DISTINCT change_value_id",                          :conditions => ["status = 1 and merchant_id = ? and province_id =? and channel_id in (select id from channels where status = 1)",                          merchant_id, province_id]).map { |cv| cv.change_value_id }.compact    support_amount_s = ChangeValue.find(:all,:select => "price" ,:conditions => ["id in (?)", support_amount_a])                                     .map { |cv| cv.try(:price).to_i }.compact 
[b]4.发送post请求 可以在shell中执行  [/b]
[u]复制代码[/u] 代码如下:
curl -d "channel=中信异度支付&action_type=娱人节-手机充值&user_indicate=13911731997&original_amount=10000" http://xx.xxx.xxx:3000/search.json 
[b]5.Ruby 中纯数据结构 ( Struct 与 OpenStruct )[/b] 讲一下它俩之间的区别: Struct 需要开头明确声明字段; 而 OpenStruct 人如其名, 随时可以添加属性 Struct 性能优秀; 而 OpenStruct 差点, 具体的性能差距可看这里:http://stackoverflow.com/questions/1177594/ruby-struct-vs-openstruct Struct 是 Ruby 解释器内置, 用 C 实现; OpenStruct 是 Ruby 标准库, Ruby 实现 API 不同: Struct API 与 OpenStruct [b]6. MIme::Type.register[/b]
[u]复制代码[/u] 代码如下:
Mime::Type.register "application/json", :ejson  config/initializers/mime_types.rb
[b]7.config/initializers/secure_problem_solved.rb[/b]
[u]复制代码[/u] 代码如下:
ActiveSupport::CoreExtensions::Hash::Conversions::XML_PARSING.delete('symbol')  ActiveSupport::CoreExtensions::Hash::Conversions::XML_PARSING.delete('yaml') 
[b]8.config/initializers/new_rails_default.rb[/b]
[u]复制代码[/u] 代码如下:
if defined?(ActiveRecord)   # Include Active Record class name as root for JSON serialized output.   ActiveRecord::Base.include_root_in_json = true   # Store the full class name (including module namespace) in STI type column.   ActiveRecord::Base.store_full_sti_class = true end ActionController::Routing.generate_best_match = false # Use ISO 8601 format for JSON serialized times and dates. ActiveSupport.use_standard_json_time_format = true # Don't escape HTML entities in JSON, leave that for the #json_escape helper. # if you're including raw json in an HTML page. ActiveSupport.escape_html_entities_in_json = false
[b]9.MemCacheStore 缓存[/b]
[u]复制代码[/u] 代码如下:
@_cache = ActiveSupport::Cache::MemCacheStore.new(                       CONFIG['host'], { :namespace => "#{CONFIG['namespace']}::#{@name}" }                       ) localhost::callback_lock @_cache.write(pay_channel.channel_id,'true') v = @_cache.read(pay_channel.channel_id) if v.nil? || v != 'true'       return false     else       return true     end end
[b]10.联合索引[/b]
[u]复制代码[/u] 代码如下:
gem 'composite_primary_keys', '6.0.1' https://github.com/momoplan
0.Hash assert_valid_keys 白名单 [b]11.puma -C puma_service_qa.rb[/b] [b]12.pow [/b] [b]13. Time[/b]
[u]复制代码[/u] 代码如下:
start_time = start_time.to_s.to_datetime.at_beginning_of_day end_time = end_time.to_s.to_datetime.end_of_day
[b]14.merchant.instance_of? MplusMerchant[/b]
[u]复制代码[/u] 代码如下:
m_order[:merchant_id] = (merchant.instance_of? MplusMerchant) ? merchant.id : merchant 
[b]15.will_paginate rails[/b] 安装之后需要修改config/environment.rb文件 在文件的最后添加:
[u]复制代码[/u] 代码如下:
require 'will_paginate' 修改controller文件中的index方法: #    @products = Product.find(:all)     @products = Product.paginate  :page => params[:page],                                   :per_page => 2   .pagination     = will_paginate @mplus_orders, :class => 'digg_pagination' 最好有个include
[b]16. # Excel Generator[/b]
[u]复制代码[/u] 代码如下:
gem 'spreadsheet', '~> 0.7.3'  PROVINCE = %w{ 安徽  北京  福建  甘肃  广东  广西  贵州  海南  河北  河南  黑龙江 湖北       湖南  吉林  江苏  江西  辽宁  内蒙古 宁夏  青海  山东  山西  陕西  上海       四川  天津  西藏   新疆  云南  浙江  重庆 }   MONTH = 1.upto(12).to_a   def self.total_to_xls(year = '2012', opts = {})     book = Spreadsheet::Workbook.new     sheet1 = book.create_worksheet     months = MONTH     months = opts[:month].to_s.split(/,/) if opts[:month]     fixed_row = months.collect{ |m| m.to_s + '月' }.insert(0, '')     sheet1.row(0).concat(fixed_row)     row1 = ['']     (months.size - 1).times { row1 << ['用户数', '金额', '订单数'] }     sheet1.row(1).concat(row1.flatten!)     row = 2     sheet1.row(row).insert(0, '全国')     months.each_with_index do |m, i|       sheet1.row(row).insert(i*3 + 1, self.monthly_users_count(m))       sheet1.row(row).insert(i*3 + 2, self.monthly_amount(m))       sheet1.row(row).insert(i*3 + 3, self.monthly_orders_count(m))         end     PROVINCE.each do |province|       row += 1       sheet1.row(row).insert(0, province)       months.each_with_index do |m, i|         sheet1.row(row).insert(i*3 + 1, self.monthly_users_count_by_province(m, province))         sheet1.row(row).insert(i*3 + 2, self.monthly_amount_by_province(m, province))         sheet1.row(row).insert(i*3 + 3, self.monthly_orders_count_by_province(m, province))       end       end     path = "tmp/phone_recharge.xls"     book.write path     path   end
[b]17. inject({})[/b]
[u]复制代码[/u] 代码如下:
selected_conditions = base_conditions.inject({}) do |hash, data|       hash[data.first] = data.last unless data.last.blank?       hash     end
[b]18.time_str.instance_of?[/b]
[u]复制代码[/u] 代码如下:
return time_str if time_str.instance_of? Time
[b]19.Person.instance_eval[/b]
[u]复制代码[/u] 代码如下:
Person.instance_eval do     def species       "Homo Sapien"     end   end
[b]20.class_eval[/b]
[u]复制代码[/u] 代码如下:
class Foo   end   metaclass = (class << Foo; self; end)   metaclass.class_eval do       def species         "Homo Sapien"       end     end   end
[b]21.Ruby中 respond_to? 和 send 的用法[/b] http://galeki.is-programmer.com/posts/183.html 因为obj对象没法响应talk这个消息,如果使用 respond_to? 这个方法,就可以实现判断对象能否响应给定的消息了
[u]复制代码[/u] 代码如下:
obj = Object.new if obj.respond_to?("talk")    obj.talk else    puts "Sorry, object can't talk!" end   request = gets.chomp   if book.respond_to?(request)   puts book.send(request) else   puts "Input error" end
[b]22.method_missing,一个 Ruby 程序员的梦中情人 [/b]
[u]复制代码[/u] 代码如下:
    def method_missing(method, *args)       if method.to_s =~ /(.*)_with_cent$/         attr_name = $1         if self.respond_to?(attr_name)           '%.2f' % (self.send(attr_name).to_f / 100.00)         else           super         end       end     end
[b]23.chomp[/b] chomp方法是移除字符串尾部的分离符,例如n,r等...而gets默认的分离符是n [b]24. hash.each_pair{|k,v|} & send()[/b]
[u]复制代码[/u] 代码如下:
if bank_order.present?           data_hash.each_pair { |k, v| bank_order.send("#{k}=", v) }         else           bank_order = BankOrder.new data_hash         end
[b]25.config.middleware 通过 rake -T 可以查看, 在config/ - 去除不必的 middleware[/b] [b]26.1.day.ago.strftime('%Y%m%d') [/b]
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