old_contents: # -*- coding: utf-8 -*-
  ##############################################################################
  #
  #    Copyright (C) 2018 Compassion CH (http://www.compassion.ch)
  #    Releasing children from poverty in Jesus' name
  #    @author: Emanuel Cino <ecino@compassion.ch>
  #
  #    The licence is in the file __manifest__.py
  #
  ##############################################################################
  from openupgradelib import openupgrade
  
  
  @openupgrade.migrate(use_env=True)
  def migrate(env, version):
      if not version:
          return
  
      # Put a default file_name in correspondence to allow retrieving them.
      env.cr.execute("""
          UPDATE correspondence
          SET file_name = kit_identifier || '.pdf'
      """)
  
      # Migrate correspondence template image
      attachment_obj = env['ir.attachment']
      templates = env['correspondence.template'].search([])
      for template in templates:
          # Restore pattern image from database
          env.cr.execute("""
              SELECT pattern_image FROM correspondence_template
              WHERE id = %s
          """, [template.id])
          pattern_image = env.cr.fetchone()[0]
  
          # Restore template image from ir.attachment
          template_image = None
          attachment = attachment_obj.search([
              ('res_model', '=', 'correspondence.template'),
              ('res_id', '=', template.id)])
          if attachment:
              template_image = attachment.datas
              attachment.unlink()
  
          template.write({
              'pattern_image': pattern_image,
              'template_image': template_image.encode('base64')
          })
  
new_contents: # -*- coding: utf-8 -*-
  ##############################################################################
  #
  #    Copyright (C) 2018 Compassion CH (http://www.compassion.ch)
  #    Releasing children from poverty in Jesus' name
  #    @author: Emanuel Cino <ecino@compassion.ch>
  #
  #    The licence is in the file __manifest__.py
  #
  ##############################################################################
  from openupgradelib import openupgrade
  
  
  @openupgrade.migrate(use_env=True)
  def migrate(env, version):
      if not version:
          return
  
      # Put a default file_name in correspondence to allow retrieving them.
      env.cr.execute("""
          UPDATE correspondence
          SET file_name = kit_identifier || '.pdf'
      """)
  
      # Migrate correspondence template image
      attachment_obj = env['ir.attachment']
      templates = env['correspondence.template'].search([])
      for template in templates:
          # Restore pattern image from database
          env.cr.execute("""
              SELECT pattern_image FROM correspondence_template
              WHERE id = %s
          """, [template.id])
          pattern_image = env.cr.fetchone()[0]
  
          # Restore template image from ir.attachment
          template_image = None
          attachment = attachment_obj.search([
              ('res_model', '=', 'correspondence.template'),
              ('res_id', '=', template.id)])
          if attachment:
              template_image = attachment.datas
              attachment.unlink()
  
          template.write({
              'pattern_image': pattern_image,
              'template_image': template_image and template_image.encode(
                  'base64')
          })
  
subject: FIX migration issue