Fallbacks to base theme and inheritance

[iamdriz]

How can we have it so that if no theme is found it falls back to the default app/views?

And using this same mechanism would it be possible to get it to first look in the theme folder, then have a parent theme to fallback to and then finally the default Rails folder if it can't be found.

[yogeshjain999]

As given in the README, you could either define method or Proc for this in the controller.

theme :default_theme

private

def default_theme
  theme || parent_theme || "layout_name"
end

[iamdriz]

@yogeshjain999 So you pass the default layout as the fallback theme?

[yogeshjain999]

Correct @iamdriz. It is because search locations includes app/themes and app/views Dir.

[iamdriz]

@yogeshjain999 That being said though.... If I have:

theme :theme_resolver

private

def theme_resolver
  'a_theme_that_doesnt_exist' || 'a_theme_that_does_exist' || 'application'
end

I'm finding that instead of it falling back to the 'a_theme_that_does_exist' it falls straight back to the default views. Probably because I have a value for the first theme (even though it doesn't exist) in the operator and it will try and find that and then just fallback... what I want it to do is fallback on a view-basis to the next operator value and then the default views if those can't be found either. To achieve that, would I need to manually check if the view requested existed first based on the currently requested theme and then try the next one until defaulting to application?

[yogeshjain999]

That being said, easiest way I can see is doing it like,

def theme_resolver
  theme_present?('a_theme_that_doesnt_exist') || 'application'
end

def theme_present?(name)
  return name if Rails.application.paths["app/themes/#{name}"].present?
end

[iamdriz]

@yogeshjain999 The theme may exist but the view for that particular request may not.

[iamdriz]

In order to get the fallback theme to work I had to do:

before_action :fallback_theme
def fallback_theme
  self.prepend_view_path 'app/themes/fallback_theme/views'
end

[iamdriz]

It also turns out that it doesn't actually use the fallback string:

def theme_resolver
  params[:theme] || 'I CAN PUT ANYTHING HERE'
end

So it would be good to pass back a nil if no theme is specified. Rather than a string that is basically ignored as the default paths are already in the view_paths. Just feels a bit of a hack.

[iamdriz]

After playing around with this I've come to find that building a Rails Engine is probably a better way forward as then it means you can have everything a Rails app would have on a theme basis.