From 5d56830de9a57f99b4ec35445343d1771a27a19f Mon Sep 17 00:00:00 2001
From: Liz Conlan <liz@mysociety.org>
Date: Tue, 28 May 2019 11:38:28 +0100
Subject: [PATCH] Use the Rails config.to_prepare hook to load the theme assets

Rails 5 has introduced changes to the load order so now
`Rails.application.config.assets.paths` is populated later - as part of
the initialization process - so when our original code tries to prepend
theme paths from `initializers/theme_loader.rb`, it is adding to an
empty array which results in our custom paths being the last to be
searched after the Rails and core app paths have been loaded.

The `after_initialize` hook is too late as - if caching is in effect -
the Sprockets environment has been cached at this point (and the path
array is frozen), and changing `Rails.application.config.assets` has no
effect. As `Rails.config.to_prepare` runs after the initializers but
while changes can still be made and only runs once (at boot-up) in
production so it should be a good choice:

https://guides.rubyonrails.org/configuring.html#initializers
---
 lib/alavetelitheme.rb | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/lib/alavetelitheme.rb b/lib/alavetelitheme.rb
index 278b2f33..70d59234 100644
--- a/lib/alavetelitheme.rb
+++ b/lib/alavetelitheme.rb
@@ -15,16 +15,6 @@ def set_whatdotheyknow_view_paths
     alias :set_view_paths :set_whatdotheyknow_view_paths
 end
 
-# Prepend the asset directories in this theme to the asset path:
-['stylesheets', 'images', 'javascripts'].each do |asset_type|
-    theme_asset_path = File.join(File.dirname(__FILE__),
-                                 '..',
-                                 'app',
-                                 'assets',
-                                 asset_type)
-    Rails.application.config.assets.paths.unshift theme_asset_path
-end
-
 # Append individual theme assets to the asset path
 theme_asset_path = File.join(File.dirname(__FILE__),
                              '..',
@@ -50,6 +40,22 @@ def set_whatdotheyknow_view_paths
   ActiveSupport::Dependencies.autoload_once_paths.delete(path)
 end
 
+def prepend_theme_assets
+  # Prepend the asset directories in this theme to the asset path:
+  ['stylesheets', 'images', 'javascripts'].each do |asset_type|
+      theme_asset_path = File.join(File.dirname(__FILE__),
+                                   '..',
+                                   'app',
+                                   'assets',
+                                   asset_type)
+      Rails.application.config.assets.paths.unshift theme_asset_path
+  end
+end
+
+Rails.application.config.to_prepare do
+  prepend_theme_assets
+end
+
 # Monkey patch app code
 for patch in ['patch_mailer_paths.rb',
               'controller_patches.rb',