add custom field values to api.

app/controllers/api/v2/planning_elements_controller.rb

@@ -200,8 +200,22 @@ module Api
 
       end
 
+      def convert_object_to_struct(model)
+        OpenStruct.new(model.attributes)
+      end
+
+      def convert_wp_object_to_struct(model)
+        result = convert_object_to_struct(model)
+        result.custom_values = model.custom_values.select{|cv| cv.value != ""}.map do |model|
+            convert_object_to_struct(model)
+        end
+        result
+      end
+
       def convert_to_struct(collection)
-        collection.map{|model| OpenStruct.new(model.attributes)}
+        collection.map do |model|
+          convert_wp_object_to_struct(model)
+        end
       end
 
       def planning_comparison?
@@ -223,7 +237,7 @@ module Api
       def current_work_packages(projects)
         work_packages = WorkPackage.for_projects(projects)
                                    .changed_since(@since)
-                                   .includes(:status, :project, :type)
+                                   .includes(:status, :project, :type, :custom_values)
 
         if params[:f]
           #we need a project to make project-specific custom fields work

app/models/timeline.rb

@@ -180,6 +180,10 @@ class Timeline < ActiveRecord::Base
     json.html_safe
   end
 
+  def custom_field_columns
+    project.all_work_package_custom_fields.map { |a| {name: a.name, id: "cf_#{a.id}"}}
+  end
+
   def available_columns
     @@available_columns
   end

app/views/api/v2/planning_elements/index.api.rabl

@@ -50,4 +50,8 @@ node :due_date, :if => lambda{|pe| pe.due_date.present?} {|pe| pe.due_date.to_fo
 node :created_at, if: lambda{|pe| pe.created_at.present?} {|pe| pe.created_at.utc}
 node :updated_at, if: lambda{|pe| pe.updated_at.present?} {|pe| pe.updated_at.utc}
 
-
+node do |element|
+  element.custom_values.each do |ele|
+    node(:"cf_#{ele.custom_field_id}") { ele.value }
+  end
+end