fix bug

app/services/exercise_user_pdf_service.rb

@@ -3,7 +3,7 @@ class ExerciseUserPdfService
   include ApplicationHelper
   include StudentWorksHelper
 
-  attr_reader :exercise, :ex_user
+  attr_reader :exercise, :ex_user, :request_url
 
   def initialize(exercise, ex_user,request_url)
     @exercise = exercise

app/services/export_exercises_service.rb

@@ -1,9 +1,9 @@
 class ExportExercisesService
   include ExercisesHelper
   include StudentWorksHelper
-  attr_reader :exercise, :ex_users
+  attr_reader :exercise, :ex_users, :request_url
 
-  def initialize(exercise, ex_users,request_url)
+  def initialize(exercise, ex_users, request_url)
     @exercise = exercise
     @ex_users = ex_users
     @request_url = request_url
@@ -19,7 +19,7 @@ class ExportExercisesService
     pdfs = []
     Zip::File.open(zip_file.path, Zip::File::CREATE) do |zip|
       ex_users.each do |ex_user|
-        export = ExerciseUserPdfService.new(exercise, ex_user,request_url)
+        export = ExerciseUserPdfService.new(exercise, ex_user,@request_url)
         pdf = export.ex_pdf
         pdfs << pdf
         begin