Rails - Parameter with multiple values in the URL when consuming an API via Active Resource

http://guides.rubyonrails.org/action_controller_overview.html#hash-and-array-parameters

Try :filter[] => value, :filter[] => value2

to create a valid query string, you can use

params = {a: 1, b: [1,2]}.to_query

http://apidock.com/rails/Hash/to_query
http://apidock.com/rails/Hash/to_param