* Add the join manager + tests
* Documentation for join manager
* Use order_by for consistent tests
* Use postgres instead sqlite for tests for better reliability
* Fix coverage
* Drop django 1.8
Django starting with 1.9 switched to using a class to provide an
iterator for the querymanager. Between 1.9 and 1.10 changes slowly
stopped referencing that function and instead started calling
_iterator_class directly.
As the functionality model-utils is patching has moved, this patch moves
the iterator logic to a class to match the changes that have been made
in Django in version 1.9.
As Django 1.8 is a LTS release that is still supported, iterator()
is retained in the InheritanceQuerySetMixin and can be removed when
support for Django 1.8 is removed. This goes for the try-except in the
import statements as well.
InheritanceQuerySet with `select_subclasses` applied as strings
raised AttributeError exception.
Adds a new test case `test_dj19_values_list_on_select_subclasses`
InheritanceQuerySetMixin._clone signature conflicts with django
ValuesQuerySet._clone code which calls super like this:
"c = super(ValuesQuerySet, self)._clone(klass, **kwargs)"
By itself, .instance_of(*models) will actually call select_subclasses(*models),
which results in just those objects being cast to subclasses.
However, if you want the casting to grandchildren (which is supported only in
django 1.6+), then you may use an extra call to .select_subclasses() (without
arguments, to select all subclasses).
It doesn't deal with @kezabelle's discussion of mixed-use of select_subclasses/
instance_of, I still need to look at that.
But it does pass all current tests...
This is based upon the feature in django-polymorphic, where you
can do:
SuperClass.objects.instance_of(SubClass)
This will result in only objects of the subclass being fetched.
Note: this works with any queryset, keeping the filtering and
ordering applied there.
When subclassing Django will copy managers from the ancestor class. Copying in turn calls `copy.copy()` which checks whether the object uses `__slots__` or `__dict__`. This could result in the manager calling `self.get_queryset()` before all models get registered with the ORM.
