如何通过ruby中的变量访问冒号哈希键

Question

我有一个哈希数组,我想写一个通用的检查器,所以我想传入要检查的键的名称.散列是使用带冒号前缀(符号)的键定义的.我无法弄清楚如何正确使用变量作为键.即使密钥存在于散列中,使用变量访问它也会导致nil.如何通过变量访问哈希键？也许另一种要问的方法是,如何将变量强制转换为符号？

在IRB中,我这样做:

>> family = { 'husband' => "Homer", 'wife' => "Marge" }
=> {"husband"=>"Homer", "wife"=>"Marge"}
>> somevar = "husband"
=> "husband"
>> family[somevar]
=> "Homer"
>> another_family  = { :husband => "Fred", :wife => "Wilma" }
=> {:husband=>"Fred", :wife=>"Wilma"}
>> another_family[somevar]
=> nil
>>

Answer 1

您想先将字符串转换为符号:

another_family[somevar.to_sym]

如果您不想担心散列是符号还是字符串,只需将其转换为符号键即可

请参阅:如何转换Ruby哈希以使其所有键都是符号？

Answer 2

您可以使用 Active Support gem 来访问该with_indifferent_access方法：

require 'active_support/core_ext/hash/indifferent_access'
> hash = { somekey: 'somevalue' }.with_indifferent_access
 => {"somekey"=>"somevalue"}
> hash[:somekey]
 => "somevalue"
> hash['somekey']
=> "somevalue"