相关疑难解决方法(0)

哪种款式首选？一个与另一个有充分的理由吗？

提前致谢!

1) cmds.each do |cmd|
   end

2) cmds.each { |cmd|
   }

示例代码:

cmds = [ "create", "update", "list", "help" ]

# Block style one
#
cmds.each do |cmd|
  puts "loop1, cmd: #{cmd}"
end

# Block style two
#
cmds.each { |cmd|
  puts "loop2, cmd: #{cmd}"
}

大家好我想创建一个范围,找出所有0地址的联系人.Got error message ArgumentError: tried to create Proc object without a block在rails c中运行命令'Contact.noaddress'时.

这是我的联系模式,包括范围

class Contact < ActiveRecord::Base
  attr_accessible :email, :firstname, :lastname, :mobilephone, :fullname
  has_many :addresses
  validates_presence_of :firstname, :lastname


   scope :noaddressed, lambda do |addresses|
    joins(:addresses).where('addresses.created_at.empty?', true)
   end
end

这是地址模型

class Address < ActiveRecord::Base
  attr_accessible :city, :country, :postalcode, :region, :street
  belongs_to :contact
end

有人可以帮帮我吗？非常感谢.

我的应用程序中有许多多行ActiveRelation查询方法,我不确定编写这些方法的最惯用方法.看看这个例子:

def postal_code_ids_within(miles)
  nearby_postal_codes = PostalCode.where("latitude > :min_lat and latitude < :max_lat",
    min_lat: (latitude - (miles.to_f / MILES_PER_DEGREE_LATITUDE.to_f / 2.to_f)),
    max_lat: (latitude + (miles.to_f / MILES_PER_DEGREE_LATITUDE.to_f / 2.to_f)))
  nearby_postal_codes = nearby_postal_codes.where("longitude > :min_lon and longitude < :max_lon",
    min_lon: (longitude - (miles.to_f / MILES_PER_DEGREE_LONGITUDE.to_f / 2.to_f)),
    max_lon: (longitude + (miles.to_f / MILES_PER_DEGREE_LONGITUDE.to_f / 2.to_f)))
  nearby_postal_codes.pluck(:id)
end

对我来说感觉有点不对劲.从中返回ActiveRelation对象的块似乎是惯用的,但我还没有看到这种方法.

什么是标准？