Question

This question is a follow up to my previous unanswered question: ActionView::MissingTemplate: Missing template (Trying to render nonexistent :mobile format )

Since doesn’t seem to be a Rails approach consensus with this, Is there any way that when accessing from a mobile device to render default :html when :mobile format is not available? (If a :mobile view is present should have priority over those who are not mobile formatted).

Answer 1

assume you got a mobile_request? controller instance method to detect mobile requests, then you should be able to set format fallback chains:

# application_controller.rb
before_filter :set_request_format, :set_format_fallbacks

respond_to :html, :mobile # etc

def set_request_format
  request.format = :mobile if mobile_request?
end

def set_format_fallbacks
  if request.format == :mobile
    self.formats = [:mobile, :html]
  end
end

This should work but apparently it doesn’t completely.
https://github.com/rails/rails/issues/3855
If you have a mobile template, the format seems to get locked and it will not find a partial with only html.

Hopefully it will be fixed some way or other.
In the meantime you can put this <% controller.set_format_fallbacks %> in each template (ouch) or write your own resolver.
http://jkfill.com/2011/03/11/implementing-a-rails-3-view-resolver/

also look at:

Can a mobile mime type fall back to "html" in Rails?

Changing view formats in rails 3.1 (delivering mobile html formats, fallback on normal html)