Django: Creating an Inline Formset Similar to the Admin Interface

Question

I'm a Django newbie, and I have a question about reusing the inline formset of the admin interface in the production code. Consider the following model:

class Attribute(models.Model):
    name       = models.CharField(max_length=50)

class Person(models.Model):
    lastName   = models.CharField(max_length=50)
    firstName  = models.CharField(max_length=50)
    email      = models.CharField(max_length=50)
    attributes = models.ManyToManyField(Attribute, through='AttributeValue')

class AttributeValue(models.Model):
    person     = models.ForeignKey(Person, on_delete=models.CASCADE)
    attribute  = models.ForeignKey(Attribute, on_delete=models.PROTECT)
    isConsumer = models.BooleanField()
    value      = models.CharField(max_length=50)

The admin interface for this comes out beautifully. I used the following admin.py:

class AttributeValueInline(admin.TabularInline):
    model = AttributeValue
    extra = 3

class PersonAdmin(admin.ModelAdmin):
    list_display = ('lastName', 'firstName','email')
    fieldsets = [
       ('Name',        {'fields': ['firstName', 'lastName']}),
       ('Contact Info',{'fields': ['email','phoneNumber']})
    ]
    inlines = [AttributeValueInline]

admin.site.register(Person, PersonAdmin)
admin.site.register(Attribute)

This is almost exactly what I want. It looks like this:

When I tried to implement the same in the non-admin website, I had to write quite a bit of code to do the inline formsets, form processing, in addition to the actual business logic. In addition to this, I faced the problem mentioned here.

I can't expose the admin interface to the end-user because we need to have a customized web design, and page flow. But, can I reuse parts of the admin interface code instead of re-implementing the same functionality?

Any other suggestions to reduce the code would be most welcome.

Answer 1

Here is the answer how to implement inline formsets like in Django admin http://kevindias.com/writing/django-class-based-views-multiple-inline-formsets/ However only CreateWiew is described. If you want to implement also UpdateView you need to do duplicate your code for it with a little tweaks

def get(self, request, *args, **kwargs):
    """
    Handles GET requests and instantiates blank versions of the form
    and its inline formsets.
    """
    self.object = self.get_object()
    form_class = self.get_form_class()
    form = self.get_form(form_class)
    sample_form = SampleFormSet(instance=self.object)
    return self.render_to_response(
        self.get_context_data(form=form,
                              sample_form=sample_form))

def post(self, request, *args, **kwargs):
    """
    Handles POST requests, instantiating a form instance and its inline
    formsets with the passed POST variables and then checking them for
    validity.
    """
    self.object = self.get_object()
    form_class = self.get_form_class()
    form = self.get_form(form_class)
    sample_form = SampleFormSet(self.request.POST, instance=self.object)
    if (form.is_valid() and sample_form.is_valid()):
        return self.form_valid(form, sample_form)
    else:
        return self.form_invalid(form, sample_form)

def form_valid(self, form, sample_form):
    """
    Called if all forms are valid. Creates a Recipe instance along with
    associated Ingredients and Instructions and then redirects to a
    success page.
    """
    self.object = form.save()
    sample_form.save()
    return HttpResponseRedirect(self.get_success_url())

and don`t forget to add DELETE formset field to your template

          {% for form in sample_form %}
          {{ form.id }}
          <div class="inline {{ sample_form.prefix }}">
              {{ form.description.errors }}
              {{ form.description.label_tag }}
              ...
              {{ form.DELETE }}
          </div>
          {% endfor %}