问动物在/ ValueError _ValueError/7/

EN

{% extends "zoo_animal_feeders/base.html" %}
{% load bootstrap3 %}

{% block header %}
  <h2><a href="{% url 'zoo_animal_feeders:animal_type' animal_type.id %}">{{ animal_type }}</a></h2>
  <h2>Add new animal:</h2>
{% endblock header %}

{% block content %}
  <form action="{% url 'zoo_animal_feeders:new_animal' animal_type.id %}" method='post' class="form">
    {% csrf_token %}
    {% bootstrap_form form %}

    {% buttons %}
      <button name='submit'>add animal</button>
    {% endbuttons %}
  </form>

{% endblock content %}

@login_required
def new_animal(request, animal_type_id):
    """Add a new animal to an animal type"""
    animal_type = AnimalType.objects.get(id=animal_type_id)

    if request.method != 'POST':
        #create a blank form
        form = AnimalForm()
    else:
        #POST data submitted
        form = AnimalForm(data=request.POST)
        if form.is_valid():
            new_animal = form.save(commit=False)
            new_animal.animal_type = animal_type
            new_animal.save()
            return HttpResponseRedirect(reverse('zoo_animal_feeders:animal_type', args=[animal_type_id]))

context = {'animal_type':animal_type, 'form':form}
return render(request, 'zoo_animal_feeders/new_animal.html', context)

class AnimalType(models.Model):
    """Type of animal that can classify the animal"""
    owner = models.ForeignKey(User, on_delete=models.CASCADE)
    a_type = models.CharField(max_length=50, default='')
    date_added = models.DateField(auto_now_add=True)

    def __str__(self):
        return self.a_type