Hash keys exist?

ruby-talk
1

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

···

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2

Keep this open as someone might have the answer but I have reworked the
way in which I store my hash.

···

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3

irb(main):001:0> example = {
irb(main):002:1* :profile => { :name => "John", :username => "johnny_bravo"},
irb(main):003:1* :example1 => { :var1 => "test", :var2 => "test2" },
irb(main):004:1* }
=> {:profile=>{:name=>"John", :username=>"johnny_bravo"},
:example1=>{:var1=>"test", :var2=>"test2"}}

irb(main):005:0> [:name, :username, :var1].all? {|k| example.has_key? k}
=> false
irb(main):006:0> [:profile, :example1].all? {|k| example.has_key? k}
=> true

Cheers

robert

···

On Tue, Jan 18, 2011 at 11:05 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.

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

4

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

···

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/\.