如何避免NoMethodError嵌套散列中缺失的元素,无需重复零检查? [英] How to avoid NoMethodError for missing elements in nested hashes, without repeated nil checks?
问题描述
我正在寻找一种避免在深度嵌套哈希的每个级别检查 nil
的好方法。例如:
name = params [:company] [:owner] [:name] if params [:company]& &安培; params [:company] [:owner]&& params [:company] [:owner] [:name]
这需要三次检查,非常丑陋的代码。任何方式来解决这个问题?
Ruby 2.3.0引入了一个名为 它返回 如果您使用的是早于2.3的Ruby版本,则可以使用 ruby_dig gem 或自行实施: I'm looking for a good way to avoid checking for This requires three checks, and makes for very ugly code. Any way to get around this? Ruby 2.3.0 introduced a new method called It returns If you are using a version of Ruby older than 2.3, you can use the ruby_dig gem or implement it yourself:
这篇关于如何避免NoMethodError嵌套散列中缺失的元素,无需重复零检查?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋! dig
的新方法 Hash $ c
$ b
完全解决了这个问题。 params.dig(:company,:owner,:name)
nil
如果在任何级别缺失密钥。
模块RubyDig
def dig(key,* rest)
if value =(self [key] rescue nil)
if rest.empty?
value
elsif value.respond_to?(:dig)
value.dig(* rest)
end
end
end
end
如果RUBY_VERSION< '2.3'
Array.send(:include,RubyDig)
Hash.send(:include,RubyDig)
end
nil
at each level in deeply nested hashes. For example:name = params[:company][:owner][:name] if params[:company] && params[:company][:owner] && params[:company][:owner][:name]
dig
on both Hash
and Array
that solves this problem entirely.name = params.dig(:company, :owner, :name)
nil
if the key is missing at any level.module RubyDig
def dig(key, *rest)
if value = (self[key] rescue nil)
if rest.empty?
value
elsif value.respond_to?(:dig)
value.dig(*rest)
end
end
end
end
if RUBY_VERSION < '2.3'
Array.send(:include, RubyDig)
Hash.send(:include, RubyDig)
end