Ruby的25个编程细节
Ruby的25个编程细节
发布时间:2015-06-06 来源:查字典编辑
摘要:这篇文章主要介绍了Ruby的25个编程细节(技巧、实用代码段),本文直接给出主题和相应代码,需要的朋友可以参考下1.try永远不会抛出异常在...

这篇文章主要介绍了Ruby的25个编程细节(技巧、实用代码段),本文直接给出主题和相应代码,需要的朋友可以参考下

1.try 永远不会抛出异常 在 没有的时候 返回 nil

代码如下:

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

2.find(:first, :condotions) 方法 不言而与

代码如下:

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

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

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

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" 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:/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

代码如下:

Mime::Type.register "application/json", :ejson

config/initializers/mime_types.rb

7.config/initializers/secure_problem_solved.rb

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

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

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

代码如下:

gem 'composite_primary_keys', '6.0.1'

https:///momoplan

0.Hash assert_valid_keys 白名单

11.puma -C puma_service_qa.rb

12.pow

13. Time

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

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:

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

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({})

代码如下:

selected_conditions = base_conditions.inject({}) do |hash, data|

hash[data.first] = st unless st.blank?

hash

end

18.time_str.instance_of?

代码如下:

return time_str if time_str.instance_of? Time

19.Person.instance_eval

代码如下:

Person.instance_eval do

def species

"Homo Sapien"

end

end

20.class_eval

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

galeki.is-/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

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

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()

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')

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