基于一个属性的不区分大小写的equals方法 [英] case insensitive equals method based on one attribute

问题描述

这是一个非常可怕的方法，它基于代码检查是否相等，但不区分大小写

This is a really horrible method, which checks for equality on base of the code but case agnostic

def ==(another_country)
   (code.nil? ? nil : code.downcase) == (another_country.code.nil? ? nil : another_country.code.downcase) unless another_country.nil?
end

您能为我指明正确的方向，如何在不使用其他结构的情况下编写更优雅的文章吗?

Can you point my in the right direction how to write this more elegant w/o reliying on ugly if else structures?

# Country model
class Country < ActiveRecord::Base
  attr_accessible :code

  def ==(another_country)
    code.to_s.downcase == another_country.code.to_s.downcase rescue false
  end
end

广泛测试:

# RSpec
describe Country do
   describe 'equality based solely on Country.code' do
      before do
        @country_code_de = FactoryGirl.build(:country, :code => 'de')
      end

      it 'should be equal if Country.code is equal' do
        other_country_code_de = FactoryGirl.build(:country, :code => 'de')
        @country_code_de.should == other_country_code_de
      end

      it 'should be not equal if Country.code is not equal' do
        country_code_usa = FactoryGirl.build(:country, :code => 'usa')
        @country_code_de.should_not == country_code_usa
      end

      it 'should be case insensitive' do
        country_code_de_uppercase = FactoryGirl.build(:country, :code => 'DE')
        @country_code_de.should == country_code_de_uppercase
      end

      it 'should not rely on id for equality' do
        @country_code_de.id = 0
        country_code_usa = FactoryGirl.build(:country, :code => 'usa', :id => 0)
        @country_code_de.should_not == country_code_usa
      end

      it 'should be not equal if Country.code of one Country is nil' do
        country_code_nil = FactoryGirl.build(:country, :code => nil)
        @country_code_de.should_not == country_code_nil
      end

      it 'should be equal if Country.code for both countries is nil' do
        country_code_nil = FactoryGirl.build(:country, :code => nil)
        other_country_code_nil = FactoryGirl.build(:country, :code => nil)
        country_code_nil.should == other_country_code_nil
      end

      it 'should be not equal if other Country is nil' do
        @country_code_de.should_not == nil
      end

      it 'should be not equal if other object is not a Country' do
        @country_code_de.should_not == 'test'
      end

      it 'should be equal for descendants of Country with same Country.code' do
        class CountryChild < Country
        end
        country_child = CountryChild.new(:code => 'de')
        @country_code_de.should == country_child
      end
    end
end

推荐答案

如何解决这个问题，

def ==(another_country)
   return false if code.blank? # Remove this line if you want to return true if code and antoher_country.code are nil
   code.to_s.downcase == another_country.to_s.code.downcase rescue false
end

如果code，another_country或another_country.code中的任何一个为nil，它将通过一个异常，并且rescue false语句将返回false值.

Here if any of code, another_country or another_country.code is nil, it will through up an exception and rescue false statement will return false value.

如果一切顺利，将进行比较，并根据输入内容返回true or false.

If everything goes well, the comparison will happen and true or false will be returned based on the input.

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