title: Django 'ManagementForm data is missing or has been tampered with' when saving modelForms with foreign key link
body: <p>I am rather new to Django so this may be an easy question. I have 2 modelForms where there is a ForeignKey to another. My main goal is to save Indicators with a link to Disease (FK), such that for a particular disease, you can have multiple indicators. </p>
  
  <p>With the code below, I get an error when I hit submit that says 'ManagementForm data is missing or has been tampered with'. Also, the code in views.py does not seem to be validating at the 3rd 'if' statement where there is a return HttpResponseRedirect. However, when I check my database, the values from the form have been written. Any ideas on why the error has been raised? and how to fix it?</p>
  
  <p>My code is below:</p>
  
  <p>models.py</p>
  
  <pre><code>#Table for Disease
  class Disease(models.Model):
      disease = models.CharField(max_length=300)
  
  #Tables for Indicators
  class Indicator(models.Model):
      relevantdisease = models.ForeignKey(Disease)       
      indicator = models.CharField(max_length=300)
  </code></pre>
  
  <p>forms.py</p>
  
  <pre><code>class DiseaseForm(forms.ModelForm):
      class Meta:
        model = Disease
  
  class IndicatorForm(forms.ModelForm):
      class Meta:
        model = Indicator
  
  DiseaseFormSet = inlineformset_factory(Disease, 
      Indicator,
      can_delete=False,
      form=DiseaseForm)
  </code></pre>
  
  <p>views.py</p>
  
  <pre><code>def drui(request):
  
      if request.method == "POST":
  
         indicatorForm  = IndicatorForm(request.POST)
  
         if indicatorForm.is_valid():
            new_indicator = indicatorForm.save()
            diseaseInlineFormSet = DiseaseFormSet(request.POST, request.FILES,   instance=new_indicator)
  
            if diseaseInlineFormSet.is_valid():
               diseaseInlineFormset.save()
               return HttpResponseRedirect('some_url.html')
  
      else:
         indicatorForm = IndicatorForm()
         diseaseInlineFormSet = DiseaseFormSet()
  
      return render_to_response("drui.html", {'indicatorForm': indicatorForm,  'diseaseInlineFormSet': diseaseInlineFormSet},context_instance=RequestContext(request))   
  </code></pre>
  
  <p>template.html</p>
  
  <pre><code> &lt;form class="disease_form" action="{% url drui %}" method="post"&gt;{% csrf_token %}
    {{ indicatorForm.as_table }}
   &lt;input type="submit" name="submit" value="Submit" class="button"&gt;
   &lt;/form&gt;
  </code></pre>