Django - Query from a sub-table - django-models

Question

I have an application that has a dropdown menu among other things.
The menu is created based on the requirements. I wrote a query that checks the statuses and calculates how many requirements are in a given status. Then he builds a menu out of it. However, I have a problem because sometimes a requisition has been created but no items have been added to it. In that case, my menu shows this as one of the items. This is not what he expects. I would like the query to return and count only those requirements in a given status that have children.
Below I paste the model code and inquiries.
class D_DemandStatus(ModelBaseClass):
status = models.CharField(max_length=20, unique=True)
name = models.CharField(max_length=50)
created_user = models.ForeignKey(User, on_delete=models.PROTECT)
def save(self, *args, **kwargs):
user = get_current_user()
if user and not user.pk:
user = None
if not self.pk:
self.created_user = user
self.modified_by = user
super(D_DemandStatus, self).save(*args, **kwargs)
def __str__(self):
return self.name
class Meta:
verbose_name = 'Demand status'
verbose_name_plural = 'Demands status'
class Demand(models.Model):
name = models.CharField(max_length=500)
status = models.ForeignKey(D_DemandStatus, default=3, on_delete=models.PROTECT, )
insert_user = models.ForeignKey(User, on_delete=models.PROTECT, editable=False)
insert_date = models.DateTimeField(default=datetime.datetime.now, editable=False)
def save(self, *args, **kwargs):
user = get_current_user()
if user and not user.pk:
user = None
if not self.pk:
self.insert_user = user
self.status = D_DemandStatus.objects.get(status='PREPARED')
self.modified_by = user
super(Demand, self).save(*args, **kwargs)
def __str__(self):
return self.name
def submitt(self, *args, **kwargs):
if self.pk :
dict_status = D_DemandStatus.objects.get(status='WAITING')
print(dict_status)
self.demanddetails_set.filter(demand_id = self.pk).update(status=dict_status)
self.status = dict_status
self.save()
def status_actualize(self, *args, **kwargs):
if self.pk :
dict_status = D_DemandStatus.objects.get(status='ORDERED')
items_status = DemandDetails.objects.filter(demand=self.pk).values('status').distinct()
if len(items_status) == 1 and items_status[0]['status'] == dict_status.id :
self.status = D_DemandStatus.objects.get(status='ORDERED')
#elif len(items_status) > 1 :
# self.status = D_DemandStatus.objects.get(status='INPROGRESS')
self.save()
class Meta:
verbose_name = 'Demand'
verbose_name_plural = 'Demands'
class DemandDetails(models.Model):
demand = models.ForeignKey(Demand, on_delete=models.CASCADE, related_name='items')
component = models.ForeignKey(Component, on_delete=models.CASCADE)
order_item = models.ForeignKey(OrderItem, null=True, on_delete=models.PROTECT, editable=False, related_name='demand_details_item')
quantity = models.IntegerField(default=1)
comment = models.CharField(max_length=150, blank=True)
status = models.ForeignKey(D_DemandStatus, default=3, on_delete=models.PROTECT, )
insert_user = models.ForeignKey(User, on_delete=models.PROTECT, editable=False)
insert_date = models.DateTimeField(auto_now_add=True)
def quantityUpdate(self, val):
if self.pk :
self.quantity = val
self.save()
def save(self, *args, **kwargs):
user = get_current_user()
if user and not user.pk:
user = None
if not self.pk:
self.insert_user = user
self.status = D_DemandStatus.objects.get(status='PREPARED')
if not self.pk:
try:
super(DemandDetails, self).save(*args, **kwargs)
except IntegrityError as e:
obj = DemandDetails.objects.get(demand_id=self.demand_id, component_id=self.component_id)
obj.quantity = obj.quantity + 1
obj.save()
else:
super(DemandDetails, self).save(*args, **kwargs)
def __str__(self):
return self.demand.name
class Meta:
verbose_name = 'Demand detail'
verbose_name_plural = 'Demand details'
constraints = [
models.UniqueConstraint(fields=['demand_id', 'component_id'], name='epm - DemandDetail (demand, component)' )
]
The query that works now looks like this:
demand_list = Demand.objects.values('status__name', 'status__id', 'status__status').annotate(count=Count('status__name')).filter(Q(status__status='WAITING') | Q(status__status='PREPARED')).order_by('-status__name')
In this case, however, even if the demand is empty (no items added), it is counted as 1
So I have changed the code a little, but it doesn't work as I would like, because it also counts the individual elements of the demand - which is obvious, because the query returns the subsequent rows that are counted.
demand_list = Demand.objects.values('status__name', 'status__id', 'status__status').annotate(count=Count('status__name'), piece=Count('demanddetails')).filter(Q(piece__gte=1)).filter(Q(status__status='WAITING') | Q(status__status='PREPARED')).order_by('-status__name')
I need to write the query in such a way that I get a list of statuses with numbers of demands only which have derived elements in DemandDetails. If a Demand exists but has no derived elements then it is not taken into account - rather it is counted as 0. This is important because in the extreme case there may be only one Demand which is empty and then I want to have information about it in the menu but with the number 0.
I hope I have managed to write clearly what I chaie.
Please help me to create a suitable query.
Regards