FEATURE: support serializing user custom fields by plugins

app/serializers/current_user_serializer.rb

@@ -72,9 +72,20 @@ class CurrentUserSerializer < BasicUserSerializer
   end
 
   def custom_fields
-    return {} unless SiteSetting.public_user_custom_fields.present?
+    fields = nil
-    fields = User.custom_fields_for_ids([object.id], SiteSetting.public_user_custom_fields.split('|'))
+    if SiteSetting.public_user_custom_fields.present?
-    return fields.present? ? fields[object.id] : {}
+      fields = SiteSetting.public_user_custom_fields.split('|')
+    end
+    DiscoursePluginRegistry.serialized_current_user_fields.each do |f|
+      fields ||= []
+      fields << f
+    end
+
+    if fields.present?
+      User.custom_fields_for_ids([object.id], fields)[object.id]
+    else
+      {}
+    end
   end
 
 end

lib/discourse_plugin_registry.rb

@@ -13,6 +13,8 @@ class DiscoursePluginRegistry
     attr_accessor :sass_variables
     attr_accessor :handlebars
     attr_accessor :custom_html
+    attr_accessor :serialized_current_user_fields
+
 
     # Default accessor values
     def javascripts
@@ -46,6 +48,10 @@ class DiscoursePluginRegistry
     def handlebars
       @handlebars ||= Set.new
     end
+
+    def serialized_current_user_fields
+      @serialized_current_user_fields ||= Set.new
+    end
   end
 
   def register_js(filename, options={})

spec/components/plugin/instance_spec.rb

@@ -161,6 +161,18 @@ describe Plugin::Instance do
     end
   end
 
+  context "serialized_current_user_fields" do
+    it "correctly serializes custom user fields" do
+      DiscoursePluginRegistry.serialized_current_user_fields << "has_car"
+      user = Fabricate(:user)
+      user.custom_fields["has_car"] = "true"
+      user.save!
+
+      payload = JSON.parse(CurrentUserSerializer.new(user, scope: Guardian.new(user)).to_json)
+      payload["current_user"]["custom_fields"]["has_car"].should == "true"
+    end
+  end
+
   context "register_color_scheme" do
     it "can add a color scheme for the first time" do
       plugin = Plugin::Instance.new nil, "/tmp/test.rb"