How to pass pk of detail view into fk of form - django

Question

Good afternoon, I am fairly new to Django and I am not sure how to go about this.I have a Django 2.2 project with these models:
class Equipment(models.Model):
name = models.CharField(
max_length=15,
unique=True,
verbose_name='asset name')
asset_cat = models.ForeignKey('category',on_delete=models.PROTECT,verbose_name='asset category')
asset_loc = models.ForeignKey('location',on_delete=models.PROTECT,verbose_name='asset location')
state = models.ForeignKey('status',on_delete=models.PROTECT,verbose_name='status')
brand = models.CharField(
max_length=15,
unique=False,
blank=True)
model = models.CharField(
max_length=12,
unique=False,
blank=True,
verbose_name='model number')
def __str__(self):
return "{}".format(self.name)
def get_absolute_url(self):
return reverse('equipment-detail', args=[str(self.id)])
class Meta:
ordering = ['asset_cat', 'name']
verbose_name_plural = 'pieces of equipment'
class Action(models.Model):
name = models.ForeignKey('equipment',on_delete=models.PROTECT,verbose_name='asset name',blank=False)
dt = models.DateTimeField(
auto_now_add=True,
verbose_name='date and time of incident')
incident = models.TextField(
blank=True,
null=True)
CHANGE = 'CHANGE'
SERVICE = 'SERVICE'
ACTION_CHOICES = (
(CHANGE, 'CHANGE'),
(SERVICE, 'SERVICE')
)
act = models.TextField(
blank=True,
choices=ACTION_CHOICES,
null=True,
verbose_name='action taken')
act_detail = models.TextField(
verbose_name='action detail',
blank=False)
result = models.TextField(
blank=True,
null=True)
def __str__(self):
return self.name
def get_absolute_url(self):
return reverse('service-detail', args=[str(self.id)])
class Meta:
ordering = ['-dt']
verbose_name_plural = 'service calls'
I have an Equipment Detail View like this:
class EquipmentDetailView(generic.DetailView):
model = Equipment
template_name = 'equipment_detail.html'
def get_context_data(self, **kwargs):
context = super(EquipmentDetailView, self).get_context_data(**kwargs)
return context
The detail view has two buttons: edit and service. If I click edit I have a model form that allows me to edit that instance of the Equipment model successfully.
However, when I click the service button, my form comes up to create an instance of the Action model, but when I submit it tells me that the null value in name_id violates the not null constraint.
It looks like my question is, how can I pass equipment.id from the Equipment Detail view to action.name of the action create form and keep the service button concept?
Action Form:
class ServiceForm(forms.ModelForm):
class Meta:
model = Action
fields = ['incident', 'act_detail', 'result']
Action (actually service) view:
class EquipmentServiceView(generic.CreateView):
template_name = 'equipment_service.html'
form_class = ServiceForm
queryset = Action.objects.all()

Answer 1

Assuming you don't want to go with simpliest solution to include name in form fields and have urls setup as:
/equipment/<id> - equipment detail view
/service - service (or action) create view
There are several ways of passing equipment id:
1) From url
We are going to change url to accept equipment_id. That means instead of /service you will have url /equipment/<equipment_id>/service.
Probably best solution - you will use URL according to REST architecture and will have very clear structure. Client can access page from anywhere (like just copy paste link from mail) and it will work.
urls.py:
urlpatterns = [
path('equipment/<int:pk>', EquipmentDetailView.as_view(), name='equipment-detail'),
path('equipment/<int:equipment_pk>/service', EquipmentServiceView.as_view(), name='service-create')
]
Your service button should look like this: service
and finally your view:
class EquipmentServiceView(CreateView):
template_name = 'equipment_service.html'
form_class = ServiceForm
queryset = Action.objects.all()
def form_valid(self, form):
equipment_pk = self.kwargs['equipment_pk']
equipment = get_object_or_404(Equipment, pk=equipment_pk)
self.object = form.save(commit=False)
self.object.name = equipment
self.object.save()
return super().form_valid(form)
2) Session data
In case you want to preserve service url without adding equipment_id, you can store equipment id either in session data(on your server) or in cookies(on client). That's not exactly good - client have to go to EquipmentDetailView prior to creating Service, but this will keep your urls intact.
views.py:
class EquipmentDetailView(DetailView):
model = Equipment
template_name = 'equipment_detail.html'
def get(self, request, *args, **kwargs):
response = super().get(request, *args, **kwargs)
request.session['last_equipment_pk'] = self.object.pk
return response
class EquipmentServiceView(CreateView):
template_name = 'equipment_service.html'
form_class = ServiceForm
queryset = Action.objects.all()
def form_valid(self, form):
equipment_pk = self.request.session.get('last_equipment_pk')
equipment = get_object_or_404(Equipment, pk=equipment_pk)
self.object = form.save(commit=False)
self.object.name = equipment
self.object.save()
return super().form_valid(form)
P.S.: name is bad field name for ForeignField - should be something like equipment or so. Those labels usually associate with CharField and expected to be strings.