Add Rails.env to RailsContext

[robwise]

Heroku Preboot is a feature on Heroku that allows for faster deploy times. When you promote your staging app to production, Preboot simply switches the production server to point at the staging app's container. This means it can deploy much faster since it doesn't have to rebuild anything.

However, this means that if you use the Define Plugin to provide the rails environment to your client code as a variable, that variable will erroneously still have a value of Staging instead of Production. Providing Rails.env (which is accurate even in Preboot) in the default Rails context would be a nice enhancement.

[justin808]

@robwise Easy to add, either via a custom Rails Context enhancement (no PR required) or as a default for the RailsContext.

See this example: https://github.com/shakacode/react_on_rails/blob/master/spec/dummy/config/initializers/react_on_rails.rb#L4

module RenderingExtension
  # Return a Hash that contains custom values from the view context that will get passed to
  # all calls to react_component and redux_store for rendering
  def self.custom_context(view_context)
    if view_context.controller.is_a?(ActionMailer::Base)
      {}
    else
      {
        somethingUseful: view_context.session[:something_useful]
      }
    end
  end
end

[robwise]

@justin808 yeah I'm already doing it the custom way, I'm saying I think it should be a default

[justin808]

@robwise Maybe for features, we'll do if any of our Coaching Clients or regular clients want it? Otherwise, we can wait for the PR to come in. Or maybe if the issue gets at least 20 up votes.

[robwise]

okay, and maybe just having this issue as a historical record will be good enough in case other people are using preboot and are not realizing that because the webpack isn't being recompiled, the variables may be stale and to watch out for that

[jonathanphilippou]

i'm gonna take it

[justin808]

Fixed in #1065.