我有一个这样的散列:
params = { :irrelevant => "A String",
:choice1 => "Oh look, another one",
:choice2 => "Even more strings",
:choice3 => "But wait",
:irrelevant2 => "The last string" }
我想要一个简单的方法来拒绝所有不是choice+int的键。可以是choice1,或者从choice1到choice10。它变化。
我如何用单词选择和后面的一个或多个数字来挑选键?
奖金:
将散列转换为以tab (\t)作为分隔符的字符串。我这样做了,但它花了几行代码。通常大师级的卢比手可以在一行或几行内完成。
params = { :irrelevant => "A String",
:choice1 => "Oh look, another one",
:choice2 => "Even more strings",
:choice3 => "But wait",
:irrelevant2 => "The last string" }
choices = params.select { |key, value| key.to_s[/^choice\d+/] }
#=> {:choice1=>"Oh look, another one", :choice2=>"Even more strings", :choice3=>"But wait"}
关于奖金问题:
If you have output from #select method like this (list of 2-element arrays):
[[:choice1, "Oh look, another one"], [:choice2, "Even more strings"], [:choice3, "But wait"]]
then simply take this result and execute:
filtered_params.join("\t")
# or if you want only values instead of pairs key-value
filtered_params.map(&:last).join("\t")
If you have output from #delete_if method like this (hash):
{:choice1=>"Oh look, another one", :choice2=>"Even more strings", :choice3=>"But wait"}
then:
filtered_params.to_a.join("\t")
# or
filtered_params.values.join("\t")
最简单的方法是包含gem 'activesupport'(或gem 'active_support')。
然后,在你的课上你只需要
require 'active_support/core_ext/hash/slice'
然后打电话
params.slice(:choice1, :choice2, :choice3) # => {:choice1=>"Oh look, another one", :choice2=>"Even more strings", :choice3=>"But wait"}
我认为声明其他可能有bug的函数是不值得的,最好使用在过去几年里调整过的方法。
使用散列切片
{ a: 1, b: 2, c: 3, d: 4 }.slice(:a, :b)
# => {:a=>1, :b=>2}
# If you have an array of keys you want to limit to, you should splat them:
valid_keys = [:mass, :velocity, :time]
search(options.slice(*valid_keys))