>> params
=> {:user=>{:date_i2=>7, :date_i3=>1981, :name=>"Anderson", :date_i1=>17}}
>> class User
>>   def date=(params)
>>     @date = "#{params[:date_i1]}/#{params[:date_i2]}/#{params[:date_i3]}"
>>   end
>>
>>   def date
>>     @date
>>   end
>> end
=> nil
>> u = User.new
=> #<User:0x2b6e77c22020>
>> u.date = params[:user]
=> {:date_i2=>7, :date_i3=>1981, :name=>"Anderson", :date_i1=>17}
>> u.date
=> "17/7/1981"