Question

我正在使用这个哈希数组来批量插入到mongo DB中。通过解析文本文件来填充每个哈希，因此字段的格式是不可预测的格式。它可能看起来像：

{date => "March 5", time => "05:22:21", first_name = "John", middle_initial = "JJ", ...}

我会有一系列格式化功能。也许吧：

def format_date
..convert if needed..
end

def format_time
...
end

我如何在各种记录上调用格式化函数？我可以看到做一些lambda调用，我遍历散列并调用format_record_name函数，但并非所有记录都有格式化函数。例如，first_name记录上面不需要一个。有什么想法吗？

Answer 1

只需保留您想要处理的密钥列表。您甚至可以使用Hash将其与转换函数联系起来：

transformations = { 
  :date => lambda {|date| whatever},
  :time => lambda {|time| whatever} 
}
transformations.default = lambda {|v| v}

data.map do |hash|
  Hash[ hash.map {|key, val| transformations[key][val] } ]
end

Answer 2

这是一个想法，非常类似于你所说的。您可能只为您不想格式化的字段设置了标识功能

def pass(x)
   x
end 

method_hash = {:date=>method(:your_format_date)}
method_hash.default = method(:pass)

x = {:date => "March 5", :time => "05:22:21", :first_name => "John", :middle_initial => "JJ"}
x.reduce({}) { |hsh,k|  hsh[k[0]] = method_hash[k[0]].call(k[1]); hsh }

Answer 3

利用Ruby的Singleton（或Eigen）类，然后下面的一个内容解决了你的问题：

module Formatter
  def format_date
    Date.parse(self[:date]).strftime('%Y-%m-%d')
  end

  def format_time
    self[:time].split(':')[0,2].join('-')
  end

  def format_first_name
    self[:first_name].upcase
  end

  def format
    {:date => format_date, :time => format_time, :first_name => format_first_name, :last_name => self[:last_name]}
  end
end

records = [
  {:date => 'March 05', :time => '12:13:00', :first_name => 'Wes', :last_name => 'Bailey'},
  {:date => 'March 06', :time => '09:15:11', :first_name => 'Joe', :last_name => 'Buck'},
  {:date => 'March 07', :time => '18:35:48', :first_name => 'Troy', :last_name => 'Aikmen'},
]

records.map {|h| h.extend(Formatter).format}
=> [{:date=>"2011-03-05", :time=>"12-13", :first_name=>"WES", :last_name=>"Bailey"},
 {:date=>"2011-03-06", :time=>"09-15", :first_name=>"JOE", :last_name=>"Buck"},
 {:date=>"2011-03-07", :time=>"18-35", :first_name=>"TROY", :last_name=>"Aikmen"}]

Answer 4

class Formatters
    def self.time(value)
        "FORMATTED TIME"
    end

    def self.date(value)
        "FORMATTED DATE"
    end

    def self.method_missing(name, arg)
        arg
    end
end

your_data = [{:date => "March 5", :time => "05:22:21", :first_name => "John", :middle_initial => "JJ"},
             {:date => "March 6", :time => "05:22:22", :first_name => "Peter", :middle_initial => "JJ"},
             {:date => "March 7", :time => "05:22:23", :first_name => "Paul", :middle_initial => "JJ"}]

formatted_data = your_data.map do |item|    
    Hash[ *item.map { |k, v| [k, Formatters.send(k, v)] }.flatten ]
end

格式化数据哈希的最有效方法是什么？

4 个答案: