I'm using Django's @receiver decorator for a post_save signal to create an activity log for my Batch model, and it seems the signal is being executed twice. I don't see any obvious reason for this duplication since I'm not committing data more than once.

The signal creates a gravity test when a Batch is saved (if startingGravity is provided) and logs activities for Batch, BatchNote, BatchAddition, and BatchTest events. Below are the relevant code snippets from models.py and views.py along with an example of the resulting Activity Log entries.

Code from models.py:

PYTHONCopied
class Batch(models.Model):

    def __str__(self):
        return self.name

    class Meta:
        verbose_name_plural = 'batches'

    name = models.CharField(max_length=50)
    startdate = models.DateTimeField(auto_now=True)
    enddate = models.DateTimeField(null=True, blank=True)
    lotId = models.CharField(max_length=7, null=True) # Bottledate L[2digityear][0paddedYearDays] = L22088
    size = DescriptiveQuantityField(base_units='liters', unit_choices=['liters','gallons'])
    active = models.BooleanField(default=True)
    fermenter = models.ForeignKey(Fermenter, on_delete=models.RESTRICT)
    startingGravity = QuantityField(base_units="sg")
    estimatedEndGravity = QuantityField(base_units="sg")
    category = models.ForeignKey(BatchCategory, on_delete=models.RESTRICT, blank=True, null=True)
    activity = models.ManyToManyField(ActivityLog, blank=True, related_name='batch')
    recipe = models.ForeignKey(Recipe, on_delete=models.RESTRICT, null=True, blank=True)
    aging_vessel = None
    packaging = None

    def transfer(self,src_vessel, dst_vessel):
        pass

    def complete(self):
        self.enddate = datetime.now()
        self.active = False

    def current_gravity(self):
        gravity_tests = self.tests.filter(type__shortid='specific-gravity')
        if len(gravity_tests) > 1:
            return gravity_tests.last().value
        return gravity_tests[0].value

    def percent_complete(self):
        est_fg = self.estimatedEndGravity.magnitude
        current_gravity = self.current_gravity()
        return round((self.startingGravity.magnitude - current_gravity) / (self.startingGravity.magnitude - est_fg) * 100)

# If a batch is saved with a Starting Gravity, add that test
@receiver(post_save,sender=Batch)
def addGravityTest(sender,instance,**kwargs):
    print("Adding Gravity")
    if instance.startingGravity:
        gravTest = BatchTest()
        testType = BatchTestType.objects.filter(shortid='specific-gravity')[0]
        gravTest.type = testType
        gravTest.value = instance.startingGravity
        gravTest.description = "Auto created from new batch."
        gravTest.datetime = datetime.now()
        unit = Unit.objects.filter(name__contains="specific")[0]
        gravTest.units = unit
        gravTest.batch = instance
        print("Saving gravity")
        gravTest.save()

@receiver(post_save,sender=BatchNote)
@receiver(post_save,sender=BatchAddition)
@receiver(post_save,sender=BatchTest)
@receiver(post_save,sender=Batch)
def addActivity(sender,instance,created=False,**kwargs):
    text = None
    batch = None
    date = datetime.now()
    if sender.__name__ == "Batch":
        batch = instance
        if created:
            text = "Batch Created"
        else:
            text = "Batch Modified"
    if sender.__name__ == "BatchNote":
        batch = instance.batch
        if created:
            text = "Added ["+instance.notetype.name+"] :: " + instance.text
    if sender.__name__ == "BatchAddition":
        batch = instance.batch
        if created:
            text = "Added [" + instance.name.name + "] :: " + str(instance.amount) + " " + instance.units.name
        else:
            text = "Updated [" + instance.name.name + "]"
    if sender.__name__ == "BatchTest":
        batch = instance.batch
        if created:
            text = "Added [" + instance.type.name + "] :: " + str(instance.value) + " " + instance.units.name
        else:
            text = "Updated [" + instance.type.name + "]"
    if text:
        log = ActivityLog(datetime=date,text=text)
        log.save()
        batch.activity.add(log)

Code from views.py:

PYTHONCopied
def addBatch(request, pk=None):
    if request.method == "POST":
        form = BatchAddForm(request.POST)
        if form.is_valid():

            batch = Batch()
            batch.name = form.cleaned_data['name']
            batch.startdate = form.cleaned_data['startdate']
            batch.size = form.cleaned_data['size']
            batch.startingGravity = form.cleaned_data['startingGravity']
            batch.estimatedEndGravity = form.cleaned_data['estimatedEndGravity']
            batch.fermenter = form.cleaned_data['fermenter']
            newbatch = batch.save()
            batch.recipe = form.cleaned_data['recipe']
            batch.save()
            return HttpResponseRedirect(reverse('batch', kwargs={'pk': batch.pk}))
        else:
            return render(request, template_name='batchthis/addBatch.html', context={'form': form})
    else:
        if pk:
            batch = Batch.objects.get(pk=pk)
            form = BatchAddForm(initial=model_to_dict(batch))
            form.fermenter = batch.fermenter
        else:
            form = BatchAddForm()
            form.fields['fermenter'].queryset = Fermenter.objects.filter(vessel__status=Vessel.STATUS_READY)
        return render(request, "batchthis/addBatch.html", {'form': form})

Activity Log Sample:

BASHCopied
2025-02-22 18:47 PM: Added [Specific Gravity] :: 1.108 Specific Gravity
2025-02-22 18:47 PM: Batch Created
2025-02-22 18:47 PM: Added [Specific Gravity] :: 1.108 Specific Gravity
2025-02-22 18:47 PM: Batch Modified

The issue is that I see duplicate entries being logged (for example, the gravity test appears twice), which suggests that the signal may be firing multiple times. I'm confused as to why this is happening since my code doesn't appear to commit any data twice. Has anyone experienced this before or can offer insights into what might be causing the duplicate signal execution?