Commit 512ee0f5 authored by Russell Keith-Magee's avatar Russell Keith-Magee
Browse files

Fixed #10572 -- Corrected the operation of the defer() and only() clauses when... 

Fixed #10572 -- Corrected the operation of the defer() and only() clauses when used on inherited models.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10926 bcc190cf-cafb-0310-a4f2-bffc1f526a37
parent 5b40ee32

django/db/models/query.py

+19 −1
Original line number Diff line number Diff line
@@ -190,7 +190,25 @@ class QuerySet(object): 
        index_start = len(extra_select)

        aggregate_start = index_start + len(self.model._meta.fields)



        load_fields = only_load.get(self.model)

        load_fields = []

        # If only/defer clauses have been specified,

        # build the list of fields that are to be loaded.

        if only_load:

            for field, model in self.model._meta.get_fields_with_model():

                if model is None:

                    model = self.model

                if field == self.model._meta.pk:

                    # Record the index of the primary key when it is found

                    pk_idx = len(load_fields)

                try:

                    if field.name in only_load[model]:

                        # Add a field that has been explicitly included

                        load_fields.append(field.name)

                except KeyError:

                    # Model wasn't explicitly listed in the only_load table

                    # Therefore, we need to load all fields from this model

                    load_fields.append(field.name)



        skip = None

        if load_fields and not fill_cache:

            # Some fields have been deferred, so we have to initialise

django/db/models/sql/query.py

+8 −2
Original line number Diff line number Diff line
@@ -635,10 +635,10 @@ class BaseQuery(object): 
            # models.

            workset = {}

            for model, values in seen.iteritems():

                for field, f_model in model._meta.get_fields_with_model():

                for field in model._meta.local_fields:

                    if field in values:

                        continue

                    add_to_dict(workset, f_model or model, field)

                    add_to_dict(workset, model, field)

            for model, values in must_include.iteritems():

                # If we haven't included a model in workset, we don't add the

                # corresponding must_include fields for that model, since an
@@ -657,6 +657,12 @@ class BaseQuery(object): 
                    # included any fields, we have to make sure it's mentioned

                    # so that only the "must include" fields are pulled in.

                    seen[model] = values

            # Now ensure that every model in the inheritance chain is mentioned

            # in the parent list. Again, it must be mentioned to ensure that

            # only "must include" fields are pulled in.

            for model in orig_opts.get_parent_list():

                if model not in seen:

                    seen[model] = set()

            for model, values in seen.iteritems():

                callback(target, model, values)

tests/modeltests/defer/models.py

+91 −1
Original line number Diff line number Diff line
@@ -17,6 +17,12 @@ class Primary(models.Model): 
    def __unicode__(self):

        return self.name



class Child(Primary):

    pass



class BigChild(Primary):

    other = models.CharField(max_length=50)



def count_delayed_fields(obj, debug=False):

    """

    Returns the number of delayed attributes on the given model instance.
@@ -33,7 +39,7 @@ def count_delayed_fields(obj, debug=False): 


__test__ = {"API_TEST": """

To all outward appearances, instances with deferred fields look the same as

normal instances when we examine attribut values. Therefore we test for the

normal instances when we examine attribute values. Therefore we test for the

number of deferred fields on returned instances (by poking at the internals),

as a way to observe what is going on.
@@ -98,5 +104,89 @@ Using defer() and only() with get() is also valid. 
>>> Primary.objects.all()

[<Primary: a new name>]



# Regression for #10572 - A subclass with no extra fields can defer fields from the base class

>>> _ = Child.objects.create(name="c1", value="foo", related=s1)



# You can defer a field on a baseclass when the subclass has no fields

>>> obj = Child.objects.defer("value").get(name="c1")

>>> count_delayed_fields(obj)

1

>>> obj.name

u"c1"

>>> obj.value

u"foo"

>>> obj.name = "c2"

>>> obj.save()



# You can retrive a single column on a base class with no fields

>>> obj = Child.objects.only("name").get(name="c2")

>>> count_delayed_fields(obj)

3

>>> obj.name

u"c2"

>>> obj.value

u"foo"

>>> obj.name = "cc"

>>> obj.save()



>>> _ = BigChild.objects.create(name="b1", value="foo", related=s1, other="bar")



# You can defer a field on a baseclass

>>> obj = BigChild.objects.defer("value").get(name="b1")

>>> count_delayed_fields(obj)

1

>>> obj.name

u"b1"

>>> obj.value

u"foo"

>>> obj.other

u"bar"

>>> obj.name = "b2"

>>> obj.save()



# You can defer a field on a subclass

>>> obj = BigChild.objects.defer("other").get(name="b2")

>>> count_delayed_fields(obj)

1

>>> obj.name

u"b2"

>>> obj.value

u"foo"

>>> obj.other

u"bar"

>>> obj.name = "b3"

>>> obj.save()



# You can retrieve a single field on a baseclass

>>> obj = BigChild.objects.only("name").get(name="b3")

>>> count_delayed_fields(obj)

4

>>> obj.name

u"b3"

>>> obj.value

u"foo"

>>> obj.other

u"bar"

>>> obj.name = "b4"

>>> obj.save()



# You can retrieve a single field on a baseclass

>>> obj = BigChild.objects.only("other").get(name="b4")

>>> count_delayed_fields(obj)

4

>>> obj.name

u"b4"

>>> obj.value

u"foo"

>>> obj.other

u"bar"

>>> obj.name = "bb"

>>> obj.save()



# Finally, we need to flush the app cache for the defer module.

# Using only/defer creates some artifical entries in the app cache

# that messes up later tests. Purge all entries, just to be sure.

>>> from django.db.models.loading import cache

>>> cache.app_models['defer'] = {}



"""}