Multiple input properties

[iainbeeston]

I often find I have to use multiple input properties to get the value for aa single output property. Right now you can do this, but you have to use before filters, like this:

before_normalize do |input, output|
  input['ab'] ||= input['a'] + input['b']
  input
end

That feels inelegant. What if you could define mappings with multiple "from" properties, like this:

map from('/a', '/b'), to('ab') { |a, b| a + b }

Is that something that would be worth adding? I'm happy to put some work into a PR for that if you like the idea

[dmitry]

@iainbeeston there are no way to denormalize in case of to('ab') { |a, b| a + b }, as the resulting value should have at least one of the values a or b to subsctract one from another (as in the example).