Gmaps4rails gem-Issue with map not being displayed, minimum distance is being calculated fine

textbook_controller.rb

def show

    @textbook = Textbook.find(params[:id])
    @this_user = User.find_by_id(session[:user_id])

      @textbook.user_textbook_statuses.each do |attribute|
        
        @map = Map.new(:to_location_id => attribute.user.location_id, from_location_id: 
        @this_user.location_id)
        @from_address = @map.from_location.as_json(:only => [:latitude, :longitude])
        @to_address = @map.to_location.as_json(:only => [:latitude, :longitude])
        @distance = Haversine.distance(@from_address["latitude"], @from_address["longitude"],  
        @to_address["latitude"], @to_address["longitude"]).to_ft
        @map.update_attributes(:distance => @distance)
        @map.save

        locations = [ @from_address, @to_address ]
          locations = locations.map do |marker|
              { lng: marker['longitude'], :lat => marker['latitude'] }
          end

        map = [ locations ]
        @location = map.to_json

    end
    
    @textbook_isbn = @textbook.isbn
    @results = JSON.parse(open("http://api2.campusbooks.com/12/rest/bookprices?
    key=4YMl9bgQwpcb7JzZBsr&isbn=#{@textbook_isbn}&format=json").read)
    @title = @results["response"]["page"]["book"]["title"]
    @each_offer = @results["response"]["page"]["offers"]["condition"].first["offer"]
  end