Ruby-on-rails – constant values in Rails

constantsrubyruby-on-rails

I have some data that I want to store somewhere in my Rails app because I use it for generating form fields, checking a submitted form to ensure its values are valid, etc. Basically, I want the data in one location because I make use of it in several places.

Previously, I was defining an initialize method in my controller and initializing instance variables within that method, e.g. @graph_types = ['bar', 'line']. This seemed a bad idea because that's really all initialize was being used for (initializing those values) and the instance variables could be changed later, which I don't want.

Now, I define constants outside of any method in my controller, right up at the top after my filters, and I freeze them, e.g. GraphTypes = ['bar', 'line'].freeze.

I didn't want to store such data in a config file because then I would have to keep track of an extra file, read in the file and parse it, etc. I didn't want to store this data in the database because that seems like overkill; I don't need to do any crazy LEFT OUTER JOIN-type queries combining available graph types with another of my constants, say Themes = ['Keynote', 'Odeo', '37 Signals', 'Rails Keynote'].freeze. I didn't want to store the data in environment.rb because this data only pertains to a particular controller.

Considering all this, am I going about this 'the Ruby way'?

Best Answer

For constants that don't really belong anywhere else I have a StaticData class.

  class StaticData

    GRAPH_TYPES = ['bar', 'line']

    SOMETHING_ELSE = ['A', 'B']

  end

Then I get at it with

StaticData::GRAPH_TYPES
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