Include this snippet into your model in order to use hstore in array with postgres and rails 4.0 ( fix is pending on the rails side )

pg_array_hsotre_fix.rb

module PgArrayHstoreFix
  def self.included(base)
    base.class_eval do
      before_save :serialize_array_hash
    end

    def serialize_array_hash
      self.class.attribute_names.each do |attribute|
          column_definition = self.column_for_attribute(attribute)
          if column_definition.array && column_definition.type == :hstore
            serialized_hstore_array = []
            self.send(attribute.to_sym).each do |value|
              serialized_hstore_array << value.to_s.gsub(/{|}/,'')
            end
            self.send("#{attribute}=".to_sym, serialized_hstore_array)
          end
      end
    end

  end
end

cool, thank you!

How I use this snippet?

Slap this file somewhere it will be loaded, like ./initializers Then do include PgArrayHstoreFix on your model. However, this patch doesn't quite do what we want. Nothing happens for deserialization so you just get key/value strings back instead of Ruby Hash objects.