Removing all empty elements from a hash / YAML?

Question

How would I go about removing all empty elements (empty list items) from a nested Hash or YAML file?

Answer 1

I believe it would be best to use a self recursive method. That way it goes as deep as is needed. This will delete the key value pair if the value is nil or an empty Hash.

class Hash
  def compact
    delete_if {|k,v| v.is_a?(Hash) ? v.compact.empty? : v.nil? }
  end
end

Then using it will look like this:

x = {:a=>{:b=>2, :c=>3}, :d=>nil, :e=>{:f=>nil}, :g=>{}}
# => {:a=>{:b=>2, :c=>3}, :d=>nil, :e=>{:f=>nil}, :g=>{}} 
x.compact
# => {:a=>{:b=>2, :c=>3}}

To keep empty hashes you can simplify this to.

class Hash
  def compact
    delete_if {|k,v| v.compact if v.is_a?(Hash); v.nil? }
  end
end