DEV: Make site setting type uploaded_image_list use upload IDs (#10401)

It used to be a list of concatenated upload URLs which was prone to
break.

lib/site_setting_extension.rb

@@ -209,6 +209,7 @@ module SiteSettingExtension
     MultiJson.dump(Hash[*@client_settings.map do |name|
       value = self.public_send(name)
       value = value.to_s if type_supervisor.get_type(name) == :upload
+      value = value.map(&:to_s).join("|") if type_supervisor.get_type(name) == :uploaded_image_list
       [name, value]
     end.flatten])
   end
@@ -233,10 +234,12 @@ module SiteSettingExtension
       .reject { |s, _| !include_hidden && hidden_settings.include?(s) }
       .map do |s, v|
 
-      value = public_send(s)
       type_hash = type_supervisor.type_hash(s)
       default = defaults.get(s, default_locale).to_s
 
+      value = public_send(s)
+      value = value.map(&:to_s).join("|") if type_hash[:type].to_s == "uploaded_image_list"
+
       if type_hash[:type].to_s == "upload" &&
          default.to_i < Upload::SEEDED_ID_THRESHOLD
 
@@ -482,7 +485,21 @@ module SiteSettingExtension
   def setup_methods(name)
     clean_name = name.to_s.sub("?", "").to_sym
 
-    if type_supervisor.get_type(name) == :upload
+    if type_supervisor.get_type(name) == :uploaded_image_list
+      define_singleton_method clean_name do
+        uploads_list = uploads[name]
+        return uploads_list if uploads_list
+
+        if (value = current[name]).nil?
+          refresh!
+          value = current[name]
+        end
+
+        value = value.split("|").map(&:to_i)
+        uploads_list = Upload.where(id: value).to_a
+        uploads[name] = uploads_list if uploads_list
+      end
+    elsif type_supervisor.get_type(name) == :upload
       define_singleton_method clean_name do
         upload = uploads[name]
         return upload if upload
@@ -552,7 +569,7 @@ module SiteSettingExtension
   end
 
   def clear_uploads_cache(name)
-    if type_supervisor.get_type(name) == :upload && uploads.has_key?(name)
+    if (type_supervisor.get_type(name) == :upload || type_supervisor.get_type(name) == :uploaded_image_list) && uploads.has_key?(name)
       uploads.delete(name)
     end
   end

lib/site_settings/type_supervisor.rb

@@ -182,6 +182,8 @@ class SiteSettings::TypeSupervisor
       type = get_data_type(name, val)
     elsif type == self.class.types[:enum]
       val = @defaults_provider[name].is_a?(Integer) ? val.to_i : val.to_s
+    elsif type == self.class.types[:uploaded_image_list] && val.present?
+      val = val.is_a?(String) ? val : val.map(&:id).join("|")
     elsif type == self.class.types[:upload] && val.present?
       val = val.is_a?(Integer) ? val : val.id
     end

lib/validators/selectable_avatars_enabled_validator.rb

@@ -6,7 +6,7 @@ class SelectableAvatarsEnabledValidator
   end
 
   def valid_value?(value)
-    value == "f" || SiteSetting.selectable_avatars.split("\n").size > 1
+    value == "f" || SiteSetting.selectable_avatars.size > 1
   end
 
   def error_message