Ruby的25個編程細節

2020-02-24 15:37:54

字體：大中小

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Ruby的25個編程細節大家都知道嗎？其實細節處理好的時候我們在日常工作中可能會減少一些麻煩，今天武林技術頻道小編帶你分享，希望能幫到你。

1.try 永遠不會拋出異常在沒有的時候返回 nil

復制代碼代碼如下:

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

2.find(:first, :condotions) 方法不言而與

復制代碼代碼如下:

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

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

復制代碼代碼如下:

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.發送post請求可以在shell中執行?

復制代碼代碼如下:

curl -d "channel=中信異度支付&action_type=娛人節-手機充值&user_indicate=13911731997&original_amount=10000" http://xx.xxx.xxx:3000/search.json?

5.Ruby 中純數據結構 ( Struct 與 OpenStruct )

講一下它倆之間的區別:

Struct 需要開頭明確聲明字段; 而 OpenStruct 人如其名, 隨時可以添加屬性
Struct 性能優秀; 而 OpenStruct 差點, 具體的性能差距可看這里:http://stackoverflow.com/questions/1177594/ruby-struct-vs-openstruct
Struct 是 Ruby 解釋器內置, 用 C 實現; OpenStruct 是 Ruby 標準庫, Ruby 實現
API 不同: Struct API 與 OpenStruct

6. MIme::Type.register

復制代碼代碼如下:

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

7.config/initializers/secure_problem_solved.rb

復制代碼代碼如下:

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

8.config/initializers/new_rails_default.rb

復制代碼代碼如下:

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 緩存

復制代碼代碼如下:

@_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.聯合索引

復制代碼代碼如下:

gem 'composite_primary_keys', '6.0.1'

https://github.com/momoplan

0.Hash assert_valid_keys 白名單

11.puma -C puma_service_qa.rb

12.pow

13. Time

復制代碼代碼如下:

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

復制代碼代碼如下:

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

15.will_paginate rails

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

復制代碼代碼如下:

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'

最好有個include

16. # Excel Generator

復制代碼代碼如下:

gem 'spreadsheet', '~> 0.7.3'
?PROVINCE = %w{ 安徽? 北京? 福建? 甘肅? 廣東? 廣西? 貴州? 海南? 河北? 河南? 黑龍江湖北
????? 湖南? 吉林? 江蘇? 江西? 遼寧? 內蒙古寧夏? 青海? 山東? 山西? 陜西? 上海
????? 四川? 天津? 西藏?? 新疆? 云南? 浙江? 重慶 }

? 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 << ['用戶數', '金額', '訂單數'] }

??? sheet1.row(1).concat(row1.flatten!)
??? row = 2

??? sheet1.row(row).insert(0, '全國')

??? 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({})

復制代碼代碼如下:

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

18.time_str.instance_of?

復制代碼代碼如下:

return time_str if time_str.instance_of? Time

19.Person.instance_eval

復制代碼代碼如下:

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

20.class_eval

復制代碼代碼如下:

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
因為obj對象沒法響應talk這個消息，如果使用 respond_to? 這個方法，就可以實現判斷對象能否響應給定的消息了

復制代碼代碼如下:

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，一個 Ruby 程序員的夢中情人

復制代碼代碼如下:

??? 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離符,例如/n,/r等...而gets默認的分離符是/n

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

復制代碼代碼如下:

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 通過 rake -T 可以查看，在config/ - 去除不必的 middleware

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

通過上面的介紹，想必大家對于Ruby的25個編程細節已經有了足夠的了解了，希望大家多多支持武林技術頻道！

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