mapper problem

test_mapper.rb

require 'rom-mapper'

class MyMapper1 < ROM::Mapper
  reject_keys true

  attribute :foo, from: [:bar, :baz] do |bar, baz|
    [bar, baz]
  end
end

class MyMapper2 < ROM::Mapper
  reject_keys true

  attribute :foo, from: ['bar', 'baz'] do |bar, baz|
    [bar, baz]
  end
end

class MyMapper3 < ROM::Mapper
  reject_keys true
  symbolize_keys true

  attribute :foo, from: [:bar, :baz] do |bar, baz|
    [bar, baz]
  end
end

class MyMapper4 < ROM::Mapper
  reject_keys true
  symbolize_keys true

  attribute :foo, from: ['bar', 'baz'] do |bar, baz|
    [bar, baz]
  end
end

params = [{
  'bar' => 'bar',
  'baz' => 'baz'
}]

MyMapper2.build.call(params) # => [{:foo=>[nil, nil]}]
MyMapper2.build.call(params) # => [{:foo=>["bar", "baz"]}]
MyMapper3.build.call(params) # => [{:foo=>[nil, nil]}]
MyMapper4.build.call(params) # => [{:foo=>[nil, nil]}]