title: create multiple records with odoo 10
body: <p>Here is my function create():</p>
  
  <pre><code>api.model
  def set_student_level(self):
      for record in self:
          if record.student_ids:
              for student in record.student_ids:
                  update_student_ids = self.env['ecole.partner.school'].browse(self.env.context.get('active_ids'))
                  if update_student_ids:
                      for rec in update_student_ids:
                          partner = update_student_ids.partner_id.id
                          school_year = update_student_ids.school_year.id
                          school_name = update_student_ids.school_name.id
                          school_level = update_student_ids.school_level.id
                          half_pension = update_student_ids.half_pension
                          half_pension_name = update_student_ids.half_pension_name.id
                          half_pension_begin_date = update_student_ids.half_pension_begin_date
                          half_pension_end_date = update_student_ids.half_pension_end_date
                          nursery = update_student_ids.nursery
                          nursery_name = update_student_ids.nursery_name.id
                          nursery_begin_date = update_student_ids.nursery_begin_date
                          nursery_end_date = update_student_ids.nursery_end_date
  
                      #Ecriture en dur dans la BDD
                          vals = {'partner_id': partner,
                                  'school_year': school_year,
                                  'school_name': school_name,
                                  'school_level': school_level,
                                  'half_pension': half_pension,
                                  'half_pension_name': half_pension_name,
                                  'half_pension_begin_date': half_pension_begin_date,
                                  'half_pension_end_date': half_pension_end_date,
                                  'nursery': nursery,
                                  'nursery_name': nursery_name,
                                  'nursery_begin_date': nursery_begin_date,
                                  'nursery_end_date': nursery_end_date}
  
                          res = update_student_ids.create(vals)
  
                      return res
  </code></pre>
  
  <p>My problem is when I select a record and I click on the button <code>set_student_level</code>, the insertion works in the database. However, when I select multiple records, I have an error <code>(ValueError: Expected singleton: school.partner.school (15, 68))</code>.</p>