Commit 8f5234d8 authored by Malcolm Tredinnick's avatar Malcolm Tredinnick
Browse files

Fixed #8036 -- Fixed a case when attempting to traverse non-existent related 

instances. We weren't skipping the correct output columns before processing
subsequent existing related instances. Thanks to mrmachine for the test case.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8598 bcc190cf-cafb-0310-a4f2-bffc1f526a37
parent 6056ab1b

django/db/models/query.py

+5 −3
Original line number Diff line number Diff line
@@ -794,7 +794,8 @@ def get_cached_row(klass, row, index_start, max_depth=0, cur_depth=0, 
    fields = row[index_start:index_end]

    if not [x for x in fields if x is not None]:

        # If we only have a list of Nones, there was not related object.

        return None, index_end

        obj = None

    else:

        obj = klass(*fields)

    for f in klass._meta.fields:

        if not select_related_descend(f, restricted, requested):
@@ -807,6 +808,7 @@ def get_cached_row(klass, row, index_start, max_depth=0, cur_depth=0, 
                cur_depth+1, next)

        if cached_row:

            rel_obj, index_end = cached_row

            if obj is not None:

                setattr(obj, f.get_cache_name(), rel_obj)

    return obj, index_end

tests/regressiontests/select_related_regress/models.py

+40 −0
Original line number Diff line number Diff line
@@ -49,6 +49,22 @@ class Enrollment(models.Model): 
    std = models.ForeignKey(Student)

    cls = models.ForeignKey(Class)



# Models for testing bug #8036.

class Country(models.Model):

    name = models.CharField(max_length=50)



class State(models.Model):

    name = models.CharField(max_length=50)

    country = models.ForeignKey(Country)



class ClientStatus(models.Model):

    name = models.CharField(max_length=50)



class Client(models.Model):

    name = models.CharField(max_length=50)

    state = models.ForeignKey(State, null=True)

    status = models.ForeignKey(ClientStatus)



__test__ = {'API_TESTS': """

Regression test for bug #7110. When using select_related(), we must query the

Device and Building tables using two different aliases (each) in order to
@@ -100,4 +116,28 @@ separate). 
u"std"

>>> e_related.cls.org.person.user.name

u"org"



Regression test for bug #8036: the first related model in the tests below

("state") is empty and we try to select the more remotely related

state__country. The regression here was not skipping the empty column results

for country before getting status.



>>> australia = Country.objects.create(name='Australia')

>>> active = ClientStatus.objects.create(name='active')

>>> client = Client.objects.create(name='client', status=active)



>>> client.status

<ClientStatus: ClientStatus object>

>>> Client.objects.select_related()[0].status

<ClientStatus: ClientStatus object>

>>> Client.objects.select_related('state')[0].status

<ClientStatus: ClientStatus object>

>>> Client.objects.select_related('state', 'status')[0].status

<ClientStatus: ClientStatus object>

>>> Client.objects.select_related('state__country')[0].status

<ClientStatus: ClientStatus object>

>>> Client.objects.select_related('state__country', 'status')[0].status

<ClientStatus: ClientStatus object>

>>> Client.objects.select_related('status')[0].status

<ClientStatus: ClientStatus object>

"""}