Validate model field: if value equals a key in a hash

Question

In an initializer I have a huge COUNTRY_CODES hash, with format:

{ :us => "United States, :de => "Germany" }

In my model I want to validate that the entered value is:

• present
• a key of my country code hash

How do I apporach this?

I can't use:

validates :country, :presence => true,
                    :inclusion => { :in => COUNTRY_CODES }

I've tried custom validators, but I get method errors when the value is nil, e.g. when I try to use value.to_sym, causing me to validate the validator and it becomes messy.

Trying to figure out the most DRY and efficient way of doing this.

Answer 1

You need to collect COUNTRY_CODES keys(symbols) as strings and validate for the inclusion. So use:

validates :country, :presence => true,:inclusion => { :in => COUNTRY_CODES.keys.map(&:to_s) }