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    Ruby的25个编程细节(技巧、实用代码段)

    作者:admin 时间:2021-02-07 06:19

    1.try 永远不会抛出异常 在 没有的时候 返回 nil

    复制代码 代码如下:

    province_id = Province.find_by_name(prov).try(:id) 

    2.find(:first, :condotions) 方法 不言而与

    复制代码 代码如下:

    mobile_info = MobileInfo.find(:first, :conditions => ["mobile_num = ? ", mobile_num.to_i]) 

    3.find(:all, :select, :conditions)

    复制代码 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 

    4.发送post请求 可以在shell中执行 

    复制代码 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 

    5.Ruby 中纯数据结构 ( Struct 与 OpenStruct )

    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

    6. MIme::Type.register

    复制代码 代码如下:

    Mime::Type.register "application/json", :ejson 
    config/initializers/mime_types.rb

    7.config/initializers/secure_problem_solved.rb

    复制代码 代码如下:

    ActiveSupport::CoreExtensions::Hash::Conversions::XML_PARSING.delete('symbol') 
    ActiveSupport::CoreExtensions::Hash::Conversions::XML_PARSING.delete('yaml') 

    8.config/initializers/new_rails_default.rb

    复制代码 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

    9.MemCacheStore 缓存

    复制代码 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

    10.联合索引

    复制代码 代码如下:

    gem 'composite_primary_keys', '6.0.1'

    https://github.com/momoplan

    0.Hash assert_valid_keys 白名单


    11.puma -C puma_service_qa.rb

    12.pow

    13. Time

    复制代码 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

    14.merchant.instance_of? MplusMerchant

    复制代码 代码如下:

    m_order[:merchant_id] = (merchant.instance_of? MplusMerchant) ? merchant.id : merchant 

    15.will_paginate rails

    安装之后需要修改config/environment.rb文件
    在文件的最后添加:

    复制代码 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

    16. # Excel Generator

    复制代码 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

    17. inject({})

    复制代码 代码如下:

    selected_conditions = base_conditions.inject({}) do |hash, data|
          hash[data.first] = data.last unless data.last.blank?
          hash
        end

    18.time_str.instance_of?

    复制代码 代码如下:

    return time_str if time_str.instance_of? Time

    19.Person.instance_eval

    复制代码 代码如下:

    Person.instance_eval do
        def species
          "Homo Sapien"
        end
      end

    20.class_eval

    复制代码 代码如下:

    class Foo
      end
      metaclass = (class << Foo; self; end)
      metaclass.class_eval do
          def species
            "Homo Sapien"
          end
        end
      end


    21.Ruby中 respond_to? 和 send 的用法
    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

    复制代码 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

    22.method_missing,一个 Ruby 程序员的梦中情人

    复制代码 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

    23.chomp

    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

    24. hash.each_pair{|k,v|} & send()

    复制代码 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

    25.config.middleware 通过 rake -T 可以查看, 在config/ - 去除不必的 middleware

    26.1.day.ago.strftime('%Y%m%d')

    js
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