I'm trying to figure it out why when i submit my form, my tags are not saved in my db. Pretty new with the django-rest-framework and Django-taggit too, i think i'm doing something wrong :)
First, before making my API with the rest-framework, i was using a generic view (CreateView and UpdateView) to register/validate my event. It was working fine but i decided to go further and try to build an API since i'm using Angularjs now.
Now my model event is created but without my tag and i have some errors. I put some code and i'll describe my errors after.
events/models.py
class Event(models.Model):
[...]
title = models.CharField(max_length=245, blank=False)
description = models.TextField(max_length=750, null=True, blank=True)
start = models.DateTimeField()
end = models.DateTimeField()
created_at = models.DateTimeField(editable=False)
updated_at = models.DateTimeField(editable=False)
slug = AutoSlugField(populate_from='title', unique=True, editable=False)
expert = models.BooleanField(choices=MODE_EXPERT, default=0)
home = models.BooleanField(choices=HOME, default=0)
nb_participant = models.PositiveSmallIntegerField(default=1)
price = models.PositiveSmallIntegerField(default=0)
cancelled = models.BooleanField(default=0)
user = models.ForeignKey(User, editable=False, related_name='author')
address = models.ForeignKey('Address', editable=False, related_name='events')
participants = models.ManyToManyField(User, related_name='participants', blank=True, editable=False,
through='Participants')
theme_category = models.ForeignKey('EventThemeCategory', unique=True, editable=False)
tags = TaggableManager(blank=True)
class Meta:
db_table = 'event'
def save(self, *args, **kwargs):
if not self.pk:
self.created_at = timezone.now()
self.updated_at = timezone.now()
super(Event, self).save(*args, **kwargs)
[...]
i'm using the serializers.HyperlinkedModelSerializer.
api/serializer.py
from taggit.models import Tag
class TagListSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Tag
fields = ('url', 'id', 'name')
class EventSerializer(serializers.HyperlinkedModelSerializer):
address = AddressSerializer()
user = UserSerializer(required=False)
tags = TagListSerializer(blank=True)
class Meta:
model = Event
fields = ('url', 'id', 'title', 'description', 'start', 'end', 'created_at', 'updated_at', 'slug', 'expert','home', 'nb_participant', 'price', 'address', 'user', 'theme_category', 'tags')
depth = 1
api/views/tags_views.py
from rest_framework import generics
from api.serializers import TagListSerializer
from taggit.models import Tag
class TagsListAPIView(generics.ListCreateAPIView):
queryset = Tag.objects.all()
model = Tag
serializer_class = TagListSerializer
class TagsDetailAPIView(generics.RetrieveUpdateDestroyAPIView):
queryset = Tag.objects.all()
model = Tag
serializer_class = TagListSerializer
api/views/events_views.py
class EventListAPIView(generics.ListCreateAPIView):
queryset = Event.objects.all()
model = Event
serializer_class = EventSerializer
paginate_by = 100
def pre_save(self, obj):
"""
Set the object's owner, based on the incoming request.
"""
obj.user = self.request.user
return super(EventListAPIView, self).pre_save(obj)
api/urls.py
url(r'^events/(?P<slug>[0-9a-zA-Z_-]+)/$', EventDetailAPIView.as_view(), name='event-detail'),
So first when i call /api/events/name-of-my-event the API send me the good resource with my tags on it. The GET method is working fine.
I was thinking that rest-framework follow the query set. So if i can get the resource with with all my tags why when i use POST my tags are not register ?
Actually i have two problems with the POST method:
I think i have to make a custom get_queryset(self) in my tags_views but i'm not sure. I'll will continue to investigate. If someone have already to that and have some advise, i'll be very API. Thanks.
I used to follow the following ways to serialize taggit objects but currently django-taggit provide a built in serializer https://github.com/jazzband/django-taggit/blob/master/taggit/serializers.py and it was vendor from the package I mentioned previously.
"""
Django-taggit serializer support
Originally vendored from https://github.com/glemmaPaul/django-taggit-serializer
"""
import json
# Third party
from django.utils.translation import gettext_lazy
from rest_framework import serializers
class TagList(list):
def __init__(self, *args, **kwargs):
pretty_print = kwargs.pop("pretty_print", True)
super().__init__(*args, **kwargs)
self.pretty_print = pretty_print
def __add__(self, rhs):
return TagList(super().__add__(rhs))
def __getitem__(self, item):
result = super().__getitem__(item)
try:
return TagList(result)
except TypeError:
return result
def __str__(self):
if self.pretty_print:
return json.dumps(self, sort_keys=True, indent=4, separators=(",", ": "))
else:
return json.dumps(self)
class TagListSerializerField(serializers.Field):
child = serializers.CharField()
default_error_messages = {
"not_a_list": gettext_lazy(
'Expected a list of items but got type "{input_type}".'
),
"invalid_json": gettext_lazy(
"Invalid json list. A tag list submitted in string"
" form must be valid json."
),
"not_a_str": gettext_lazy("All list items must be of string type."),
}
order_by = None
def __init__(self, **kwargs):
pretty_print = kwargs.pop("pretty_print", True)
style = kwargs.pop("style", {})
kwargs["style"] = {"base_template": "textarea.html"}
kwargs["style"].update(style)
super().__init__(**kwargs)
self.pretty_print = pretty_print
def to_internal_value(self, value):
if isinstance(value, str):
if not value:
value = "[]"
try:
value = json.loads(value)
except ValueError:
self.fail("invalid_json")
if not isinstance(value, list):
self.fail("not_a_list", input_type=type(value).__name__)
for s in value:
if not isinstance(s, str):
self.fail("not_a_str")
self.child.run_validation(s)
return value
def to_representation(self, value):
if not isinstance(value, TagList):
if not isinstance(value, list):
if self.order_by:
tags = value.all().order_by(*self.order_by)
else:
tags = value.all()
value = [tag.name for tag in tags]
value = TagList(value, pretty_print=self.pretty_print)
return value
class TaggitSerializer(serializers.Serializer):
def create(self, validated_data):
to_be_tagged, validated_data = self._pop_tags(validated_data)
tag_object = super().create(validated_data)
return self._save_tags(tag_object, to_be_tagged)
def update(self, instance, validated_data):
to_be_tagged, validated_data = self._pop_tags(validated_data)
tag_object = super().update(instance, validated_data)
return self._save_tags(tag_object, to_be_tagged)
def _save_tags(self, tag_object, tags):
for key in tags.keys():
tag_values = tags.get(key)
getattr(tag_object, key).set(tag_values)
return tag_object
def _pop_tags(self, validated_data):
to_be_tagged = {}
for key in self.fields.keys():
field = self.fields[key]
if isinstance(field, TagListSerializerField):
if key in validated_data:
to_be_tagged[key] = validated_data.pop(key)
return (to_be_tagged, validated_data)
http://blog.pedesen.de/2013/07/06/Using-django-rest-framework-with-tagged-items-django-taggit/
With the release of the Django Rest Framework 3.0, the code for the TagListSerializer has changed slightly. The serializers.WritableField was depreciated in favour for serializers.Field for the creation of custom serializer fields such as this. Below is the corrected code for Django Rest Framework 3.0.
class TagListSerializer(serializers.Field):
def to_internal_value(self, data):
if type(data) is not list:
raise ParseError("expected a list of data")
return data
def to_representation(self, obj):
if type(obj) is not list:
return [tag.name for tag in obj.all()]
return obj
I now use the bulit in taggit serializer which was taken from https://github.com/glemmaPaul/django-taggit-serializer library.
meet the same question. But I just want to save the tag list directly by TaggableManager (without TagListSerializer and TagsListAPIView). My solution is:
class MyModel(models.Model):
...
tags = TaggableManager(blank=True)
def get_tags_display(self):
return self.tags.values_list('name', flat=True)
class MyModelSerializer(serializers.HyperlinkedModelSerializer):
...
tags = serializers.Field(source='get_tags_display') # more about: http://www.django-rest-framework.org/api-guide/fields#generic-fields
...
class MyModelViewSet(viewsets.ModelViewSet):
...
def post_save(self, *args, **kwargs):
if 'tags' in self.request.DATA:
self.object.tags.set(*self.request.DATA['tags']) # type(self.object.tags) == <taggit.managers._TaggableManager>
return super(MyModelViewSet, self).post_save(*args, **kwargs)
The post data of tags data will be ['tagA', 'tagB',...], the TaggableManager will handle it. Thx.
For DRF>3.1, you just need to override create and update in your ModelSerializer class:
class StringListField(serializers.ListField): # get from http://www.django-rest-framework.org/api-guide/fields/#listfield
child = serializers.CharField()
def to_representation(self, data):
return ' '.join(data.values_list('name', flat=True)) # you change the representation style here.
class MyModelSerializer(serializers.ModelSerializer):
tags = StringListField()
class Meta:
model = models.MyModel
def create(self, validated_data):
tags = validated_data.pop('tags')
instance = super(MyModelSerializer, self).create(validated_data)
instance.tags.set(*tags)
return instance
def update(self, instance, validated_data):
# looks same as create method
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