Creating new class to put into an Array in Ruby - ruby-on-rails

Question

I am coming from a C# background and trying to learn Ruby and Ruby on Rails. I have the following Car class - note the build_xml method I need in order to build XML in that syntax and then pass to a WebService
class Car
##array = Array.new
#this will allow us to get list of all instances of cars created if needed
def self.all_instances
##array
end
def initialize(id, model_number, engine_size, no_doors)
# Instance variables
#id = id
#model_number = model_number
#engine_size = engine_size
#no_doors = no_doors
##array << self
end
def build_car_xml
car = { 'abc:Id'=> #id, 'abc:ModelNo' => #model_number, 'abc:ES' => #engine_size, 'abc:ND' => #no_doors}
cars = {'abc:Car' => [car] }
end
end
In another class then I was using this as below:
car1 = Car.new('1', 18, 3.0, 4)
request = car1.build_car_xml
This works as expected and the request is formatted how I need and the webservice returns the results. I now want to expand this however so I can pass in an array of cars and produce the request XML - however I am struggling to get this part working.
So far I have been trying the following (for now I am ok with just the Id changing as it is the only parameter required to be unique):
car_array = []
(1..10).each do |i|
car_array << Car.new(i.to_s, 18, 3.0, 4)
end
Am I correct in saying that I would need to define a new build_car_xml method on my Car class that can take an array of cars and then build the xml so my request call would be something like:
request = Car.build_car_xml(car_array)
What i am unsure of is 1) - is this the correct way of doing things in Ruby and 2) how to construct the method so that it is Building the XML in the correct format in the way it was when I call it on the single object - i.e - I need the namespaces added before the actual value.
def build_car_xml(car_array)
#here is where I am unsure how to contruct this method
end

Answer 1

Possible solution ('abc:Car' is a wrong name, should be Cars if you want it to hold an array):
class Car
...
def self.build_cars_xml(cars)
{ 'abc:Car' => cars.map(&:build_car_xml) }
end
def build_car_xml
{ 'abc:Id'=> #id, 'abc:ModelNo' => #model_number, 'abc:ES' => #engine_size, 'abc:ND' => #no_doors }
end
end
cars =
(1..10).map do |i|
Car.new(i.to_s, 18, 3.0, 4)
end
Car.build_cars_xml(cars)
It doesn't meet your requirements as instance build_car_xml doesn't generate Car namespace, but for me it's some inconsistency. Your XML is actually a collection, even if it has just one element, instance method should not be responsible for collection. Car.build_cars_xml([Car.new(...)] looks more logical to me.