Ruby/Rails - How to Create a Class and Access it from the Controller

Question

I've been trying to use a few different gems for displaying googlemaps within rails 3 and have had several problems.

Luckily I found this https://github.com/YouthTree/bhm-google-maps which is a helper and it seems to work for others.

I've installed it properly but in the readme https://github.com/YouthTree/bhm-google-maps/blob/master/README.md it mentions creating a class for the object to display in the view.

The example they gave was

class Location
   attr_accessor :address, :lat, :lng
   def initialize(address, lat, lng)
      @address = address
      @lat = lat
      @lng = lng
   end
  def to_s; address.to_s; end
end

And then running

 <%= draw_map_of Location.new("My House", 12.345, 56.789) %>

in the view.

It seems simple enough but I haven't experienced the need of creating a class before in rails so I have some questions.

Should I create a location.rb file and place the above code in it, but where should I place the file? (model folder, application folder????)

Is there a way for me to create this class within my controller?

Ideally I would like to manipulate the lat/lng values as variables and display a dynamic map.

Solution

You should put location.rb wherever you feel it makes the most sense. Having it at app/models/location.rb will ensure that it's automatically required when your app starts, but some people expect that classes in app/models are backed by ActiveRecord.

You could also put it under lib/ if you prefer.

To make it available to the app, you can include require statement in project initializers inside your config folder:

require "#{Rails.root}/lib/location.rb"

As for creating it inside your Controller - definitely! It's just another instance of a class:

def show
  @location = Location.new("My House", 12.345, 56.789)
end

And then in your view:

<%= draw_map_of @location %>

Don't forget – beneath Rails is all the power and flexibility of pure Ruby, ready to be used. You're not only limited to what Rails gives you.