From 11aee35a9fb72c470364a93186823a327d6840bb Mon Sep 17 00:00:00 2001 From: Russell Keith-Magee Date: Sun, 19 Sep 2010 14:04:34 +0000 Subject: [PATCH] Fixed #11486 -- Corrected the XML serializer to allow for the serialization of objects with a null PK value. Also includes migration of doctests to unittests (we have always been at war with doctests). Thanks to zdmytriv for the report, and Niall Kelly for the patch. git-svn-id: http://code.djangoproject.com/svn/django/trunk@13862 bcc190cf-cafb-0310-a4f2-bffc1f526a37 --- AUTHORS | 1 + django/core/serializers/xml_serializer.py | 25 +- tests/modeltests/serializers/models.py | 243 +------------ tests/modeltests/serializers/tests.py | 417 ++++++++++++++++++++++ 4 files changed, 442 insertions(+), 244 deletions(-) create mode 100644 tests/modeltests/serializers/tests.py diff --git a/AUTHORS b/AUTHORS index bf63b1057c..0cd8838cf1 100644 --- a/AUTHORS +++ b/AUTHORS @@ -251,6 +251,7 @@ answer newbie questions, and generally made Django that much better: Erik Karulf Ben Dean Kawamura Ian G. Kelly + Niall Kelly Ryan Kelly Thomas Kerpe Wiley Kestner diff --git a/django/core/serializers/xml_serializer.py b/django/core/serializers/xml_serializer.py index 5fef3b6936..bcf5631e00 100644 --- a/django/core/serializers/xml_serializer.py +++ b/django/core/serializers/xml_serializer.py @@ -42,10 +42,16 @@ class Serializer(base.Serializer): raise base.SerializationError("Non-model object (%s) encountered during serialization" % type(obj)) self.indent(1) - self.xml.startElement("object", { - "pk" : smart_unicode(obj._get_pk_val()), - "model" : smart_unicode(obj._meta), - }) + obj_pk = obj._get_pk_val() + if obj_pk is None: + attrs = {"model": smart_unicode(obj._meta),} + else: + attrs = { + "pk": smart_unicode(obj._get_pk_val()), + "model": smart_unicode(obj._meta), + } + + self.xml.startElement("object", attrs) def end_object(self, obj): """ @@ -166,11 +172,12 @@ class Deserializer(base.Deserializer): # bail. Model = self._get_model_from_node(node, "model") - # Start building a data dictionary from the object. If the node is - # missing the pk attribute, bail. - pk = node.getAttribute("pk") - if not pk: - raise base.DeserializationError(" node is missing the 'pk' attribute") + # Start building a data dictionary from the object. + # If the node is missing the pk set it to None + if node.hasAttribute("pk"): + pk = node.getAttribute("pk") + else: + pk = None data = {Model._meta.pk.attname : Model._meta.pk.to_python(pk)} diff --git a/tests/modeltests/serializers/models.py b/tests/modeltests/serializers/models.py index aac945077b..c12e73fd6e 100644 --- a/tests/modeltests/serializers/models.py +++ b/tests/modeltests/serializers/models.py @@ -18,6 +18,7 @@ class Category(models.Model): def __unicode__(self): return self.name + class Author(models.Model): name = models.CharField(max_length=20) @@ -27,6 +28,7 @@ class Author(models.Model): def __unicode__(self): return self.name + class Article(models.Model): author = models.ForeignKey(Author) headline = models.CharField(max_length=50) @@ -39,6 +41,7 @@ class Article(models.Model): def __unicode__(self): return self.headline + class AuthorProfile(models.Model): author = models.OneToOneField(Author, primary_key=True) date_of_birth = models.DateField() @@ -46,6 +49,7 @@ class AuthorProfile(models.Model): def __unicode__(self): return u"Profile of %s" % self.author + class Actor(models.Model): name = models.CharField(max_length=20, primary_key=True) @@ -55,6 +59,7 @@ class Actor(models.Model): def __unicode__(self): return self.name + class Movie(models.Model): actor = models.ForeignKey(Actor) title = models.CharField(max_length=50) @@ -66,6 +71,7 @@ class Movie(models.Model): def __unicode__(self): return self.title + class Score(models.Model): score = models.FloatField() @@ -83,6 +89,7 @@ class Team(object): def to_string(self): return "%s" % self.title + class TeamField(models.CharField): __metaclass__ = models.SubfieldBase @@ -100,6 +107,7 @@ class TeamField(models.CharField): def value_to_string(self, obj): return self._get_val_from_obj(obj).to_string() + class Player(models.Model): name = models.CharField(max_length=50) rank = models.IntegerField() @@ -107,238 +115,3 @@ class Player(models.Model): def __unicode__(self): return u'%s (%d) playing for %s' % (self.name, self.rank, self.team.to_string()) - -__test__ = {'API_TESTS':""" -# Create some data: ->>> from datetime import datetime ->>> sports = Category(name="Sports") ->>> music = Category(name="Music") ->>> op_ed = Category(name="Op-Ed") ->>> sports.save(); music.save(); op_ed.save() - ->>> joe = Author(name="Joe") ->>> jane = Author(name="Jane") ->>> joe.save(); jane.save() - ->>> a1 = Article( -... author = jane, -... headline = "Poker has no place on ESPN", -... pub_date = datetime(2006, 6, 16, 11, 00)) ->>> a2 = Article( -... author = joe, -... headline = "Time to reform copyright", -... pub_date = datetime(2006, 6, 16, 13, 00, 11, 345)) ->>> a1.save(); a2.save() ->>> a1.categories = [sports, op_ed] ->>> a2.categories = [music, op_ed] - -# Serialize a queryset to XML ->>> from django.core import serializers ->>> xml = serializers.serialize("xml", Article.objects.all()) - -# The output is valid XML ->>> from xml.dom import minidom ->>> dom = minidom.parseString(xml) - -# Deserializing has a similar interface, except that special DeserializedObject -# instances are returned. This is because data might have changed in the -# database since the data was serialized (we'll simulate that below). ->>> for obj in serializers.deserialize("xml", xml): -... print obj - - - -# Deserializing data with different field values doesn't change anything in the -# database until we call save(): ->>> xml = xml.replace("Poker has no place on ESPN", "Poker has no place on television") ->>> objs = list(serializers.deserialize("xml", xml)) - -# Even those I deserialized, the database hasn't been touched ->>> Article.objects.all() -[, ] - -# But when I save, the data changes as you might except. ->>> objs[0].save() ->>> Article.objects.all() -[, ] - -# Django also ships with a built-in JSON serializers ->>> json = serializers.serialize("json", Category.objects.filter(pk=2)) ->>> json -'[{"pk": 2, "model": "serializers.category", "fields": {"name": "Music"}}]' - -# You can easily create new objects by deserializing data with an empty PK -# (It's easier to demo this with JSON...) ->>> new_author_json = '[{"pk": null, "model": "serializers.author", "fields": {"name": "Bill"}}]' ->>> for obj in serializers.deserialize("json", new_author_json): -... obj.save() ->>> Author.objects.all() -[, , ] - -# All the serializers work the same ->>> json = serializers.serialize("json", Article.objects.all()) ->>> for obj in serializers.deserialize("json", json): -... print obj - - - ->>> json = json.replace("Poker has no place on television", "Just kidding; I love TV poker") ->>> for obj in serializers.deserialize("json", json): -... obj.save() - ->>> Article.objects.all() -[, ] - -# If you use your own primary key field (such as a OneToOneField), -# it doesn't appear in the serialized field list - it replaces the -# pk identifier. ->>> profile = AuthorProfile(author=joe, date_of_birth=datetime(1970,1,1)) ->>> profile.save() - ->>> json = serializers.serialize("json", AuthorProfile.objects.all()) ->>> json -'[{"pk": 1, "model": "serializers.authorprofile", "fields": {"date_of_birth": "1970-01-01"}}]' - ->>> for obj in serializers.deserialize("json", json): -... print obj - - -# Objects ids can be referenced before they are defined in the serialization data -# However, the deserialization process will need to be contained within a transaction ->>> json = '[{"pk": 3, "model": "serializers.article", "fields": {"headline": "Forward references pose no problem", "pub_date": "2006-06-16 15:00:00", "categories": [4, 1], "author": 4}}, {"pk": 4, "model": "serializers.category", "fields": {"name": "Reference"}}, {"pk": 4, "model": "serializers.author", "fields": {"name": "Agnes"}}]' ->>> from django.db import transaction ->>> transaction.enter_transaction_management() ->>> transaction.managed(True) ->>> for obj in serializers.deserialize("json", json): -... obj.save() - ->>> transaction.commit() ->>> transaction.leave_transaction_management() - ->>> article = Article.objects.get(pk=3) ->>> article - ->>> article.categories.all() -[, ] ->>> article.author - - -# Serializer output can be restricted to a subset of fields ->>> print serializers.serialize("json", Article.objects.all(), fields=('headline','pub_date')) -[{"pk": 1, "model": "serializers.article", "fields": {"headline": "Just kidding; I love TV poker", "pub_date": "2006-06-16 11:00:00"}}, {"pk": 2, "model": "serializers.article", "fields": {"headline": "Time to reform copyright", "pub_date": "2006-06-16 13:00:11"}}, {"pk": 3, "model": "serializers.article", "fields": {"headline": "Forward references pose no problem", "pub_date": "2006-06-16 15:00:00"}}] - -# Every string is serialized as a unicode object, also primary key -# which is 'varchar' ->>> ac = Actor(name="Zażółć") ->>> mv = Movie(title="Gęślą jaźń", actor=ac) ->>> ac.save(); mv.save() - -# Let's serialize our movie ->>> print serializers.serialize("json", [mv]) -[{"pk": 1, "model": "serializers.movie", "fields": {"price": "0.00", "actor": "Za\u017c\u00f3\u0142\u0107", "title": "G\u0119\u015bl\u0105 ja\u017a\u0144"}}] - -# Deserialization of movie ->>> list(serializers.deserialize('json', serializers.serialize('json', [mv])))[0].object.title -u'G\u0119\u015bl\u0105 ja\u017a\u0144' - -# None is null after serialization to json -# Primary key is None in case of not saved model ->>> mv2 = Movie(title="Movie 2", actor=ac) ->>> print serializers.serialize("json", [mv2]) -[{"pk": null, "model": "serializers.movie", "fields": {"price": "0.00", "actor": "Za\u017c\u00f3\u0142\u0107", "title": "Movie 2"}}] - -# Deserialization of null returns None for pk ->>> print list(serializers.deserialize('json', serializers.serialize('json', [mv2])))[0].object.id -None - -# Serialization and deserialization of floats: ->>> sc = Score(score=3.4) ->>> print serializers.serialize("json", [sc]) -[{"pk": null, "model": "serializers.score", "fields": {"score": 3.4}}] ->>> print list(serializers.deserialize('json', serializers.serialize('json', [sc])))[0].object.score -3.4 - -# Custom field with non trivial to string convertion value ->>> player = Player() ->>> player.name = "Soslan Djanaev" ->>> player.rank = 1 ->>> player.team = Team("Spartak Moskva") ->>> player.save() - ->>> serialized = serializers.serialize("json", Player.objects.all()) ->>> print serialized -[{"pk": 1, "model": "serializers.player", "fields": {"name": "Soslan Djanaev", "rank": 1, "team": "Spartak Moskva"}}] - ->>> obj = list(serializers.deserialize("json", serialized))[0] ->>> print obj - - -# Regression for #12524 -- dates before 1000AD get prefixed 0's on the year ->>> a = Article.objects.create( -... pk=4, -... author = jane, -... headline = "Nobody remembers the early years", -... pub_date = datetime(1, 2, 3, 4, 5, 6)) - ->>> serialized = serializers.serialize("json", [a]) ->>> print serialized -[{"pk": 4, "model": "serializers.article", "fields": {"headline": "Nobody remembers the early years", "pub_date": "0001-02-03 04:05:06", "categories": [], "author": 2}}] - ->>> obj = list(serializers.deserialize("json", serialized))[0] ->>> print obj.object.pub_date -0001-02-03 04:05:06 - -"""} - -try: - import yaml - __test__['YAML'] = """ -# Create some data: - ->>> articles = Article.objects.all().order_by("id")[:2] ->>> from django.core import serializers - -# test if serial - ->>> serialized = serializers.serialize("yaml", articles) ->>> print serialized -- fields: - author: 2 - categories: [3, 1] - headline: Just kidding; I love TV poker - pub_date: 2006-06-16 11:00:00 - model: serializers.article - pk: 1 -- fields: - author: 1 - categories: [2, 3] - headline: Time to reform copyright - pub_date: 2006-06-16 13:00:11 - model: serializers.article - pk: 2 - - ->>> obs = list(serializers.deserialize("yaml", serialized)) ->>> for i in obs: -... print i - - - -# Custom field with non trivial to string convertion value with YAML serializer - ->>> print serializers.serialize("yaml", Player.objects.all()) -- fields: {name: Soslan Djanaev, rank: 1, team: Spartak Moskva} - model: serializers.player - pk: 1 - - ->>> serialized = serializers.serialize("yaml", Player.objects.all()) ->>> obj = list(serializers.deserialize("yaml", serialized))[0] ->>> print obj - - - -""" -except ImportError: - pass - diff --git a/tests/modeltests/serializers/tests.py b/tests/modeltests/serializers/tests.py new file mode 100644 index 0000000000..9b648a8d4e --- /dev/null +++ b/tests/modeltests/serializers/tests.py @@ -0,0 +1,417 @@ +# -*- coding: utf-8 -*- +from datetime import datetime +from StringIO import StringIO +from xml.dom import minidom + +from django.core import serializers +from django.db import transaction +from django.test import TestCase, TransactionTestCase, Approximate +from django.utils import simplejson + +from models import Category, Author, Article, AuthorProfile, Actor, \ + Movie, Score, Player, Team + +class SerializersTestBase(object): + @staticmethod + def _comparison_value(value): + return value + + def setUp(self): + sports = Category.objects.create(name="Sports") + music = Category.objects.create(name="Music") + op_ed = Category.objects.create(name="Op-Ed") + + self.joe = Author.objects.create(name="Joe") + self.jane = Author.objects.create(name="Jane") + + self.a1 = Article( + author=self.jane, + headline="Poker has no place on ESPN", + pub_date=datetime(2006, 6, 16, 11, 00) + ) + self.a1.save() + self.a1.categories = [sports, op_ed] + + self.a2 = Article( + author=self.joe, + headline="Time to reform copyright", + pub_date=datetime(2006, 6, 16, 13, 00, 11, 345) + ) + self.a2.save() + self.a2.categories = [music, op_ed] + + def test_serialize(self): + """Tests that basic serialization works.""" + serial_str = serializers.serialize(self.serializer_name, + Article.objects.all()) + self.assertTrue(self._validate_output(serial_str)) + + def test_serializer_roundtrip(self): + """Tests that serialized content can be deserialized.""" + serial_str = serializers.serialize(self.serializer_name, + Article.objects.all()) + models = list(serializers.deserialize(self.serializer_name, serial_str)) + self.assertEqual(len(models), 2) + + def test_altering_serialized_output(self): + """ + Tests the ability to create new objects by + modifying serialized content. + """ + old_headline = "Poker has no place on ESPN" + new_headline = "Poker has no place on television" + serial_str = serializers.serialize(self.serializer_name, + Article.objects.all()) + serial_str = serial_str.replace(old_headline, new_headline) + models = list(serializers.deserialize(self.serializer_name, serial_str)) + + # Prior to saving, old headline is in place + self.assertTrue(Article.objects.filter(headline=old_headline)) + self.assertFalse(Article.objects.filter(headline=new_headline)) + + for model in models: + model.save() + + # After saving, new headline is in place + self.assertTrue(Article.objects.filter(headline=new_headline)) + self.assertFalse(Article.objects.filter(headline=old_headline)) + + def test_one_to_one_as_pk(self): + """ + Tests that if you use your own primary key field + (such as a OneToOneField), it doesn't appear in the + serialized field list - it replaces the pk identifier. + """ + profile = AuthorProfile(author=self.joe, + date_of_birth=datetime(1970,1,1)) + profile.save() + serial_str = serializers.serialize(self.serializer_name, + AuthorProfile.objects.all()) + self.assertFalse(self._get_field_values(serial_str, 'author')) + + for obj in serializers.deserialize(self.serializer_name, serial_str): + self.assertEqual(obj.object.pk, self._comparison_value(self.joe.pk)) + + def test_serialize_field_subset(self): + """Tests that output can be restricted to a subset of fields""" + valid_fields = ('headline','pub_date') + invalid_fields = ("author", "categories") + serial_str = serializers.serialize(self.serializer_name, + Article.objects.all(), + fields=valid_fields) + for field_name in invalid_fields: + self.assertFalse(self._get_field_values(serial_str, field_name)) + + for field_name in valid_fields: + self.assertTrue(self._get_field_values(serial_str, field_name)) + + def test_serialize_unicode(self): + """Tests that unicode makes the roundtrip intact""" + actor_name = u"Za\u017c\u00f3\u0142\u0107" + movie_title = u'G\u0119\u015bl\u0105 ja\u017a\u0144' + ac = Actor(name=actor_name) + mv = Movie(title=movie_title, actor=ac) + ac.save() + mv.save() + + serial_str = serializers.serialize(self.serializer_name, [mv]) + self.assertEqual(self._get_field_values(serial_str, "title")[0], movie_title) + self.assertEqual(self._get_field_values(serial_str, "actor")[0], actor_name) + + obj_list = list(serializers.deserialize(self.serializer_name, serial_str)) + mv_obj = obj_list[0].object + self.assertEqual(mv_obj.title, movie_title) + + def test_serialize_with_null_pk(self): + """ + Tests that serialized data with no primary key results + in a model instance with no id + """ + category = Category(name="Reference") + serial_str = serializers.serialize(self.serializer_name, [category]) + pk_value = self._get_pk_values(serial_str)[0] + self.assertFalse(pk_value) + + cat_obj = list(serializers.deserialize(self.serializer_name, + serial_str))[0].object + self.assertEqual(cat_obj.id, None) + + def test_float_serialization(self): + """Tests that float values serialize and deserialize intact""" + sc = Score(score=3.4) + sc.save() + serial_str = serializers.serialize(self.serializer_name, [sc]) + deserial_objs = list(serializers.deserialize(self.serializer_name, + serial_str)) + self.assertEqual(deserial_objs[0].object.score, Approximate(3.4, places=1)) + + def test_custom_field_serialization(self): + """Tests that custom fields serialize and deserialize intact""" + team_str = "Spartak Moskva" + player = Player() + player.name = "Soslan Djanaev" + player.rank = 1 + player.team = Team(team_str) + player.save() + serial_str = serializers.serialize(self.serializer_name, + Player.objects.all()) + team = self._get_field_values(serial_str, "team") + self.assertTrue(team) + self.assertEqual(team[0], team_str) + + deserial_objs = list(serializers.deserialize(self.serializer_name, serial_str)) + self.assertEqual(deserial_objs[0].object.team.to_string(), + player.team.to_string()) + + def test_pre_1000ad_date(self): + """Tests that year values before 1000AD are properly formatted""" + # Regression for #12524 -- dates before 1000AD get prefixed + # 0's on the year + a = Article.objects.create( + author = self.jane, + headline = "Nobody remembers the early years", + pub_date = datetime(1, 2, 3, 4, 5, 6)) + + serial_str = serializers.serialize(self.serializer_name, [a]) + date_values = self._get_field_values(serial_str, "pub_date") + self.assertEquals(date_values[0], "0001-02-03 04:05:06") + + def test_pkless_serialized_strings(self): + """ + Tests that serialized strings without PKs + can be turned into models + """ + deserial_objs = list(serializers.deserialize(self.serializer_name, + self.pkless_str)) + for obj in deserial_objs: + self.assertFalse(obj.object.id) + obj.save() + self.assertEqual(Category.objects.all().count(), 4) + + +class SerializersTransactionTestBase(object): + def test_forward_refs(self): + """ + Tests that objects ids can be referenced before they are + defined in the serialization data. + """ + # The deserialization process needs to be contained + # within a transaction in order to test forward reference + # handling. + transaction.enter_transaction_management() + transaction.managed(True) + objs = serializers.deserialize(self.serializer_name, self.fwd_ref_str) + for obj in objs: + obj.save() + transaction.commit() + transaction.leave_transaction_management() + + for model_cls in (Category, Author, Article): + self.assertEqual(model_cls.objects.all().count(), 1) + art_obj = Article.objects.all()[0] + self.assertEqual(art_obj.categories.all().count(), 1) + self.assertEqual(art_obj.author.name, "Agnes") + + +class XmlSerializerTestCase(SerializersTestBase, TestCase): + serializer_name = "xml" + pkless_str = """ + + + Reference + +""" + + @staticmethod + def _comparison_value(value): + # The XML serializer handles everything as strings, so comparisons + # need to be performed on the stringified value + return unicode(value) + + @staticmethod + def _validate_output(serial_str): + try: + minidom.parseString(serial_str) + except Exception: + return False + else: + return True + + @staticmethod + def _get_pk_values(serial_str): + ret_list = [] + dom = minidom.parseString(serial_str) + fields = dom.getElementsByTagName("object") + for field in fields: + ret_list.append(field.getAttribute("pk")) + return ret_list + + @staticmethod + def _get_field_values(serial_str, field_name): + ret_list = [] + dom = minidom.parseString(serial_str) + fields = dom.getElementsByTagName("field") + for field in fields: + if field.getAttribute("name") == field_name: + temp = [] + for child in field.childNodes: + temp.append(child.nodeValue) + ret_list.append("".join(temp)) + return ret_list + +class XmlSerializerTransactionTestCase(SerializersTransactionTestBase, TransactionTestCase): + serializer_name = "xml" + fwd_ref_str = """ + + + 1 + Forward references pose no problem + 2006-06-16 15:00:00 + + + + + + Agnes + + + Reference +""" + + +class JsonSerializerTestCase(SerializersTestBase, TestCase): + serializer_name = "json" + pkless_str = """[{"pk": null, "model": "serializers.category", "fields": {"name": "Reference"}}]""" + + @staticmethod + def _validate_output(serial_str): + try: + simplejson.loads(serial_str) + except Exception: + return False + else: + return True + + @staticmethod + def _get_pk_values(serial_str): + ret_list = [] + serial_list = simplejson.loads(serial_str) + for obj_dict in serial_list: + ret_list.append(obj_dict["pk"]) + return ret_list + + @staticmethod + def _get_field_values(serial_str, field_name): + ret_list = [] + serial_list = simplejson.loads(serial_str) + for obj_dict in serial_list: + if field_name in obj_dict["fields"]: + ret_list.append(obj_dict["fields"][field_name]) + return ret_list + +class JsonSerializerTransactionTestCase(SerializersTransactionTestBase, TransactionTestCase): + serializer_name = "json" + fwd_ref_str = """[ + { + "pk": 1, + "model": "serializers.article", + "fields": { + "headline": "Forward references pose no problem", + "pub_date": "2006-06-16 15:00:00", + "categories": [1], + "author": 1 + } + }, + { + "pk": 1, + "model": "serializers.category", + "fields": { + "name": "Reference" + } + }, + { + "pk": 1, + "model": "serializers.author", + "fields": { + "name": "Agnes" + } + }]""" + +try: + import yaml +except ImportError: + pass +else: + class YamlSerializerTestCase(SerializersTestBase, TestCase): + serializer_name = "yaml" + fwd_ref_str = """- fields: + headline: Forward references pose no problem + pub_date: 2006-06-16 15:00:00 + categories: [1] + author: 1 + pk: 1 + model: serializers.article +- fields: + name: Reference + pk: 1 + model: serializers.category +- fields: + name: Agnes + pk: 1 + model: serializers.author""" + + pkless_str = """- fields: + name: Reference + pk: null + model: serializers.category""" + + @staticmethod + def _validate_output(serial_str): + try: + yaml.load(StringIO(serial_str)) + except Exception: + return False + else: + return True + + @staticmethod + def _get_pk_values(serial_str): + ret_list = [] + stream = StringIO(serial_str) + for obj_dict in yaml.load(stream): + ret_list.append(obj_dict["pk"]) + return ret_list + + @staticmethod + def _get_field_values(serial_str, field_name): + ret_list = [] + stream = StringIO(serial_str) + for obj_dict in yaml.load(stream): + if "fields" in obj_dict and field_name in obj_dict["fields"]: + field_value = obj_dict["fields"][field_name] + # yaml.load will return non-string objects for some + # of the fields we are interested in, this ensures that + # everything comes back as a string + if isinstance(field_value, basestring): + ret_list.append(field_value) + else: + ret_list.append(str(field_value)) + return ret_list + + class YamlSerializerTransactionTestCase(SerializersTransactionTestBase, TransactionTestCase): + serializer_name = "yaml" + fwd_ref_str = """- fields: + headline: Forward references pose no problem + pub_date: 2006-06-16 15:00:00 + categories: [1] + author: 1 + pk: 1 + model: serializers.article +- fields: + name: Reference + pk: 1 + model: serializers.category +- fields: + name: Agnes + pk: 1 + model: serializers.author"""