undef values in hash2kv

[hozmaster]

Json syntax allows to use null values in keys.

So basically this is syntax is valid in JSON:

{ 
    "city": "London",
    "house": null
}

However, this turns output to next if I use hash2kv:

# THIS FILE IS CONTROLLED BY PUPPET

city="London"
house="undef"

What I have in mind is that output should be like next:

# THIS FILE IS CONTROLLED BY PUPPET

city="London"
house

This is what I've tried:

      if v.nil?
         kv << "#{k}"
      else
         kv << "#{k}#{settings['key_val_separator']}#{settings['quote_char']}#{v}#{settings['quote_char']}"
     end

but no avail since v is not nil. How to change ruby code so I can achieve my task ?

[mmckinst]

It looks like if you use a puppet hash and set a value to null or nil, that gets converted to a string in ruby. If you set it to undef, which is a puppet type, that gets converted to a symbol in ruby. In ruby, a symbol is just like an immutable string.

To address your problem you'd want to do something like the below code where you convert v to a string and see if it is in any of the null like strings:

if ['undef', 'null', 'nil'].include?(v.to_s)
  kv << "#{k}"
else
  kv << "#{k}#{settings['key_val_separator']}#{settings['quote_char']}#{v}#{settings['quote_char']}"
end

I tested this using the below puppet file and found it was a symbol by putting kv << v.class in the ruby code.

$config = {
  'HOSTNAME'     => 'foo.example.com',
  'RSYNC_IONICE' => '3',
  'PORTS'        => '53 123 80',
  'test_null'    => null,
  'test_nil'     => nil,
  'test_undef'   => undef,
}

file {'/tmp/config.sh':
  ensure  => 'present',
  content => hash2kv($config)
}