title: Unable to set formset fields in view
body: <p>I have try to make inlineformsets and it works but I need to set field that are not displayed in formset in the corresponding view.</p>
  <p>Model Antecedent is linked to Inclusion models with a one-to-many (FK) field (inc).</p>
  <p>I've tried to do it in is_valid() method but it dosen't work.</p>
  <p>I manage to set 'parent' (Inclusion) form sai_log field but not related 'childrens' (Antecedent) formsets sai_log fields.</p>
  <p>I know that <strong>Antecedent.objects.filter(inc__pat=self.kwargs[&quot;pk&quot;]).update(sai_log=self.request.user.username)</strong> is a correct instruction but data is not saved in database.</p>
  <p>models.py</p>
  <pre><code>class Inclusion(models.Model):
  
      pat = models.ForeignKey('Patient',on_delete = models.CASCADE, related_name='inclusion_patient', db_column='pat')
      sai_log = models.CharField('Login de l\'utilisateur ayant fait la saisie (AUTO)', max_length=50, null=True, blank=True)
  
  class Antecedent(models.Model):
     
      ide = models.AutoField(primary_key=True)
      inc = models.ForeignKey('Inclusion',on_delete = models.CASCADE, related_name='antecedent_inclusion', db_column='inc')
      sai_log = models.CharField('Login de l\'utilisateur ayant fait la saisie (AUTO)', max_length=50, null=True, blank=True)
      
  </code></pre>
  <p>views.py</p>
  <pre><code>    def form_valid(self, form):
          context = self.get_context_data()
          antecedents = context['antecedents']
          self.object = form.save(commit=False)
  
          if antecedents.is_valid():
              self.object.sai_log = self.request.user.username  # sai_log set in 'parent' form works     
              self.object.save()
              # self.kwargs[&quot;pk&quot;] =&gt; pk of patient
              Antecedent.objects.filter(inc__pat=self.kwargs[&quot;pk&quot;]).update(sai_log=self.request.user.username) # sai_log set in 'childrens' formsets doesn't works
              antecedents.instance = self.object
              antecedents.save()
          else:
              return render(self.request, self.template_name, context)
  
          return super(InclusionCreate, self).form_valid(form)
  </code></pre>