Django 1.9, Python 3.6, postgres DB
There exists Calendar and CalendarOwner, where the many-to-many relationship is defined in Calendar.
class Calendar(models.Model):
...
calendar_owners = models.ManyToManyField(
'some_app.CalendarOwner',
blank=True,
related_name='calendars',
)
...
def calendar_method(self):
return self.calendar_owners.calendar_owner_method()
class CalendarOwner(models.Model):
...
def calendar_owner_method(self):
...
# returns a bool, depends on condition
When I am calling Calendar.calendar_method() for Calendar that has CalendarOwner(s) associated with it, CalendarOwner.calendar_owner_method() is called for each CalendarOwner, and works as intended - I get a boolean according to whatever logic I have in there.
I think that the way it works is that from all the method calls, if there is at least one True the execution breaks and the return value is True.
Otherwise it will call on all the related objects and finally return False.
The question:
Why is it that when I am calling Calendar.calendar_method() when no CalendarOwner(s) are associated with Calendar it never calls CalendarOwner.calendar_owner_method() and always returns True.
Is that the default behavior?
Example:
>>> obj = Calendar()
<Calendar: Str>
>>> obj.calendar_owners.count()
0
>>> obj.calendar_owners.calendar_owner_method()
True
It makes sense that since there are no CalendarOwner(s) associated with that Calendar the CalendarOwners.calendar_owner_method() would not be called at all. But why does it return True? Can someone point me to the docs?
I can check if Calendar.calendar_owners.count() is zero and return False, but I want to see if there is any better Django way of doing that.
