From: Josh Cheek <josh.cheek@...>
Date: 2011-01-18T22:23:12+09:00
Subject: Re: Hash keys exist?

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Content-Type: text/plain; charset=ISO-8859-1

On Tue, Jan 18, 2011 at 4:05 AM, Benjamin Fowl <b.fowl87@gmail.com> wrote:

> Is there a way of checking whether a group of keys exist within a hash.
>
> For example you have the following hash
>
> example = {:profile => { :name => "John",
>                                            :username =>
> "johnny_bravo"},
>                     :example1 => { :var1 => "test",
>                                               :var2 => "test2" }
>                     }
>
> now all you want is a function that can be passed an array of required
> keys
> eg req = [:name, :username, :var1]
>
> this array can contain any number of required keys is not always just
> keys that are in either the profile or example1 sub hashes.
>
> I've looked at using the .keys method to compare keys but that requires
> me to specify where to look in the hash.
>
> Any help much apreciated
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

Here is a recursive solution


class Hash
  def nested_keys?(*target_keys)
    target_keys.all? do |target_key|
      has_key?(target_key) ||
        values.any? { |value| value.instance_of?(Hash) &&
                              value.nested_keys?(target_key)
                    }
    end
  end
end

example = {
  :profile => {
    :name => "John",
    :username => "johnny_bravo"
  },
  :example1 => {
    :var1 => "test",
    :var2 => "test2"
  },
  :example2 => {
    :nested! => {
      :three_deep => 1
    }
  },
  :value_is_nil => nil,
}

example.nested_keys? :profile # => true
example.nested_keys? :profilx # => false
example.nested_keys? :profile , :name # => true
example.nested_keys? :profile , :namx # => false
example.nested_keys? :profile , :name , :var1 # => true
example.nested_keys? :profile , :name , :varx # => false
example.nested_keys? :value_is_nil # => true
example.nested_keys? :three_deep   # => true

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