I am trying to learn how to use GenericRelations in Django-Rest-Framework.
I found the documetation page for serializer relations
<http://www.django-rest-framework.org/api-guide/relations/#the-queryset-argument>
and
followed the codes. I created the models:
class TaggedItem(models.Model): """ Tags arbitary model instance using a
generic relation. """ tag_name = models.SlugField() content_type =
models.ForeignKey(ContentType) object_id = models.PositiveIntegerField()
tagged_object = GenericForeignKey('content_type', 'object_id') def
__unicode__(self): return self.tag_name class Bookmark(models.Model): """ A
bookmark consists of a URL, and 0 or more descriptive tags. """ link_url =
models.URLField() tags = GenericRelation(TaggedItem) class Note(models.Model):
""" A note consists of some texts, and 0 or more descriptive tags """ text =
models.CharField(max_length=1000) tags = GenericRelation(TaggedItem)
I created the serializers:
class BookmarkSerializer(serializers.ModelSerializer): class Meta: model =
Bookmark fields = ('url', 'link_url', ) class
NoteSerializer(serializers.ModelSerializer): class Meta: model = Note fields =
('url', 'text', ) class TaggedObjectRelatedField(serializers.RelatedField): """
A custom field to use for the 'tagged_object' generic relationship """ def
to_representation(self, value): """ Serialize tagged objects to their
respective serializer formats :param value: :return: serializer.data """ if
isinstance(value, Bookmark): return 'Bookmark: ' + value.url elif
isinstance(value, Note): return 'Note: ' + value.text raise
Exception('Unexpected type of tagged object') class
TaggedItemSerializer(serializers.ModelSerializer): tagged_object =
TaggedObjectRelatedField() class Meta: model = TaggedItem fields = ('url',
'id', 'tag_name', 'tagged_object')
Now what should be the input to the *TaggedObjectRelatedField()* inside
*TaggedItemSerializer*? Currently I am getting error as
File
"/home/aswin/Documents/WebProjects/drf_practice/uni_auth//loginpage/login/serializers.py",
line 76, in TaggedItemSerializer tagged_object = TaggedObjectRelatedField()
File
"/home/aswin/Documents/WebProjects/drf_practice/uni_auth/lib/python3.5/site-packages/rest_framework/relations.py",
line 80, in __init__ 'Relational field must provide a `queryset` argument, '
AssertionError: Relational field must provide a `queryset` argument, override
`get_queryset`, or set read_only=`True`.
I tried giving the arguments as *read_only=True* too but it threw the same
error.just to put what i exactly did:
class TaggedItemSerializer(serializers.ModelSerializer): tagged_object =
TaggedObjectRelatedField(read_only=True)
Please help me with this. I am using django 1.9 and drf 3.4
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