Where to define Rails variable in application.html.erb

Question

I have a navbar that is placed in the /views/layouts/application.html.erb and in there I place the @buy and @sell variables which get the latest bitcoin price. They are currently placed in the /welcome controller so the prices only show when in the welcome controller. If I navigate to another controller, the bar just becomes empty.

@buy = coinbase.buy_price
@sell = coinbase.sell_price

That is the code that is currently placed in the welcome controller. I want it to be available to the navbar regardless of what controller the user is in. Any help would be great!

Answer 1

place it in the application controller and use a before action

before_action :set_prices
def set_prices
    @buy = coinbase.buy_price
    @sell = coinbase.sell_price
end

Answer 2

Two ways:

1. Write the code in application_controller as before_filter, and use the variables in nav bar.

   before_filter :prices

   def prices

   @buy = coinbase.buy_price

   @sell = coinbase.sell_price

   end

2. Write the code in application.html.erb, just before the nav bar code:

   <% @buy = coinbase.buy_price %>

   <% @sell = coinbase.sell_price %>

   And use them directly.