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Filter field of manytomany field by a list

I would like to do the following with Django REST Framework:
Filter results based on a field of a manytomany field.
The query would look like this:
https://endpoint.com/api/artwork/?having_style=Modern,Contemporary
I would expect the result to contain all ArtWork objects which contain a relation to a Style object with name "Modern", "Contemporary" or both.
The code below is not working and I don't know why.
models.py
class Style(models.Model):
name = models.CharField(validators=[validate_style], max_length=100, unique=True)
class ArtWork(models.Model):
styles = models.ManyToManyField(Style, default=None)
filters.py
class ArtWorkFilter(filters_rest.FilterSet):
having_style = django_filters.Filter(field_name="styles__name", lookup_expr='in')
class Meta:
model = ArtWork
fields = ['having_style']
class StyleSerializer(serializers.ModelSerializer):
class Meta:
model = Style
fields = ('name',)
class ArtWorkSerializer(serializers.ModelSerializer):
styles = StyleSerializer(many=True)
class Meta:
model = ArtWork
fields = ('styles'/)
views.py
class ArtWorkViewSet(viewsets.ModelViewSet):
permission_classes = []
queryset = ArtWork.objects.all()
serializer_class = ArtWorkSerializer
filter_backends = [filters_rest.DjangoFilterBackend,]
filterset_class= ArtWorkFilter
pagination_class = CursorSetPagination
Thank you in advance!
Solution
I solved it by changing the ArtWorkFilter to
filters.py
class ArtWorkFilter(filters_rest.FilterSet):
having_style = django_filters.Filter(field_name="styles__name", lookup_expr='in')
class Meta:
model = ArtWork
fields = ['having_style']
def filter_by_style_name(self, queryset, name, value):
list_styles = value.split(',')
return queryset.filter(styles__name__in=list_styles)

Try adding method param in Filter declaration. Something like:
class ArtWorkFilter(filters_rest.FilterSet):
having_style = django_filters.Filter(field_name="styles__name", lookup_expr='in')
class Meta:
model = ArtWork
fields = ['having_style']
def filter_by_style_name(self, queryset, name, value):
list_styles = value.split(',')
return queryset.filter(styles__name__in=list_styles)

CartItem.objects.filter(cart=cart, product=product, attribute__in=attribute_list).annotate(num_attr=Count('attribute')).filter(num_attr=len(attribute_list))

Django serializer, nested relation and get_or_create

I've been bugging on this issue for some time now. I have two models : Acquisitions and RawDatas.
Each RawData have one Acquisition, but many RawDatas can have the same Acquisition.
I want to create or get the instance of Acquisition automatically when I create my RawDatas. And I want to be able to have all informations using the serializer.
class Acquisitions(models.Model):
class Meta:
unique_together = (('implant', 'beg_acq', 'duration_acq'),)
id = models.AutoField(primary_key=True)
implant = models.ForeignKey("Patients", on_delete=models.CASCADE)
beg_acq = models.DateTimeField("Beggining date of the acquisition")
duration_acq = models.DurationField("Duration of the acquisition")
class RawDatas(models.Model):
class Meta:
unique_together = (('acq', 'data_type'),)
id = models.AutoField(primary_key=True)
acq = models.ForeignKey("Acquisitions", on_delete=models.CASCADE)
data_type = models.CharField(max_length=3)
sampling_freq = models.PositiveIntegerField("Sampling frequency")
bin_file = models.FileField(db_index=True, upload_to='media')
And my serializers are these :
class AcquisitionSerializer(serializers.ModelSerializer):
class Meta:
model = Acquisitions
fields = ('id', 'implant', 'beg_acq', 'duration_acq')
class RawDatasSerializer(serializers.ModelSerializer):
acq = AcquisitionSerializer()
class Meta:
model = RawDatas
fields = ('id', 'data_type', 'sampling_freq', 'bin_file', 'acq')
def create(self, validated_data):
acq_data = validated_data.pop('acq')
acq = Acquisitions.objects.get_or_create(**acq_data)
RawDatas.objects.create(acq=acq[0], **validated_data)
return rawdatas
My problem is that, using this, if my instance of Acquisitions already exists, I get a non_field_errors or another constraint validation error.
I would like to know what is the correct way to handle this please ?
So I can automatically create this using the nested serializer, and when I only want to have informations (such as a GET request), I can have all the field I need (every field of the two models).
Thanks in advance for your help !

Try this:
class AcquisitionSerializer(serializers.ModelSerializer):
class Meta:
model = Acquisitions
fields = ('id', 'implant', 'beg_acq', 'duration_acq')
class RawDatasSerializer(serializers.ModelSerializer):
class Meta:
model = RawDatas
fields = ('id', 'data_type', 'sampling_freq', 'bin_file', 'acq')
def create(self, validated_data):
acq_data = validated_data.pop('acq')
acq = Acquisitions.objects.filter(id=acq_data.get('id')).first()
if not acq:
acq = AcquisitionSerializer.create(AcquisitionSerializer(), **acq_data)
rawdata = RawDatas.objects.create(acq=acq, **validated_data)
return rawdata

Django: include get_absolute_url() in abstract model?

I'm working on a project that allows the user to fill in and save checklists needed in gastronomy.
As the checklists' content differ from one another, I decided to create an abstract base class 'checklists' with shared fields and have child models for differing attributes.
I want to find a way to dynamically create unique urls for each checklist through the abstract model.
The only way I can make it work so far is to include a get_absolute_url() in each child model - but this way I have to manually define a url in my urlpatterns and different views for each child model. Feels like unnecessary repetition.
I tried including the get_absolute_url() in my abstract model. However, this does not work because I can't seem to access the child's attributes in the abstract model.
Is there a way to include get_absolute_url() in my abstract base class?
I appreciate your help! Thanks a lot!
This is part of the code:
models.py
class Checklisten(models.Model):
# abstract model that contains shared features of all checklists
erlaubte_pruefer = models.ForeignKey(Pruefer, on_delete=models.CASCADE,
verbose_name='Prüfer')
pruefende_firma = models.ForeignKey(settings.AUTH_USER_MODEL,
on_delete=models.CASCADE, verbose_name='Unternehmen')
raum_verbindung = models.ManyToManyField(Raeume, verbose_name='Ort')
datum = models.DateField('Datum', auto_now_add=True, blank=False)
class Meta:
ordering = ['datum', 'pruefende_firma', 'raum_verbindung',
'erlaubte_pruefer']
abstract = True
verbose_name = 'Checkliste'
verbose_name_plural = 'Checklisten'
# can I include a get_absolute_url() with pk, datum AND a abbreviated 'bezeichnung' here?
class Checklisten_Schaedlinge(Checklisten):
insekten_befall = models.BooleanField('Insektenbefall', default=False)
befall_art = models.CharField('Insektenart des Befalls', blank=True,
null=True, max_length=40)
bezeichnung = 'Schädlingsmonitoring/Bekämpfung'
class Meta:
verbose_name = 'Schädlingsmonitoring/Bekämpfung'
verbose_name_plural = 'Schädlingsmonitoring/Bekämpfung'
def __str__(self):
return '%s - %s'%(self.datum, self.bezeichnung)
def get_absolute_url(self):
return reverse('checkliste-detail', kwargs={'pk' : self.pk,
'datum' : self.datum})
class Checklisten_Waagen_Thermometer(Checklisten):
WAAGE = 'WA'
THERMOMETER = 'TH'
ART = (
(WAAGE, 'Waage'),
(THERMOMETER, 'Thermometer')
)
werkzeug_art = models.CharField('Art', choices=ART, default=WAAGE,
max_length=40)
geeicht = models.BooleanField('geeicht', default=False)
naechster_eichtermin = models.DateField('Nächster Eichtermin')
bezeichnung = 'Erfassungsliste Waagen & Thermometer'
class Meta:
verbose_name = 'Erfassungsliste Waagen & Thermometer'
verbose_name_plural = 'Erfassungslisten Waagen & Thermometer'
def __str__(self):
return '%s - %s'%(self.datum, self.bezeichnung)
def get_absolute_url(self):
return reverse('checkliste-waage', kwargs={'pk' : self.pk,
'datum' : self.datum})
urls.py
urlpatterns = [
path('meine-checklisten/schaedlinge/<pk>/<datum>/, views.Checklisten_Schaedlinge_Detail_View.as_view(), name='checkliste-
schaedlinge'),
path('meine-checklisten/waagen/<pk>/<datum>/', views.Checklisten_Waagen_Detail_View.as_view(), name='checkliste-
waage'),]
views.py
class Checklisten_Schaedlinge_Detail_View(LoginRequiredMixin, DetailView):
model = Checklisten_Schaedlinge
template_name = 'checklisten/checkliste-schaedlinge-detail.html'
class Checklisten_Waagen_Detail_View(LoginRequiredMixin, DetailView):
model = Checklisten_Waagen_Thermometer
template_name = 'checklisten/checkliste-schaedlinge-detail.html'

django-tables2 custom column

I'm working now on my first Django project. I want to render results table which contains all fields from Priekabos model and one custom column from Grafikas which should contain something similar to:
SELECT max(kada_moketi) FROM grafikas WHERE priekabos_id = ?
Whatever I try from examples nothing works. Should I write another view function with that custom query:
(Grafikas.objects.filter(priekabos_id=1)
neither with:
.aggregate(Max('kada_moketi')
neither with:
.latest('kada_moketi')
worked for me I created a new table class in tables.py which later PriekabosTable will inherit? That didn't work for me too.
Here's my code:
models.py
class Grafikas(models.Model):
id = models.AutoField(primary_key=True)
mokejimo_nr = models.IntegerField()
kada_moketi = models.DateField()
priekabos = models.ForeignKey('Priekabos', models.DO_NOTHING)
class Priekabos(models.Model):
id = models.AutoField(primary_key=True)
sutarties_nr = models.CharField(unique=True, max_length=45, verbose_name='Sut. Nr.')
nuomos_pradz = models.DateField()
sutarties_trukme = models.IntegerField()
views.py
def priekabos_table(request):
table = PriekabosTable(Priekabos.objects.all())
RequestConfig(request, paginate={'per_page': 20}).configure(table)
return render(request, 'isperkamoji_nuoma/priekabos_table.html', {'table': table})
tables.py
class PriekabosTable(tables.Table):
class Meta:
model = Priekabos
attrs = {"class": "paleblue"}
fields = ('id', 'sutarties_nr', 'nuomos_pradz')
For better understanding, here's 'grafikas' table:
MySQL 'grafikas' table

It sounds like you might be able to fetch the extra field using annotate.
from django.db.models import Max
queryset = Priekabos.objects.annotate(max_kada_moketi=Max('grafikas__kada_moketi'))
table = PriekabosTable(queryset)
Remember to add the field to your table.
class PriekabosTable(tables.Table):
class Meta:
model = Priekabos
attrs = {"class": "paleblue"}
fields = ('id', 'sutarties_nr', 'nuomos_pradz', 'max_kada_moketi')

Include intermediary (through model) in responses in Django Rest Framework

I have a question about dealing with m2m / through models and their presentation in django rest framework. Let's take a classic example:
models.py:
from django.db import models
class Member(models.Model):
name = models.CharField(max_length = 20)
groups = models.ManyToManyField('Group', through = 'Membership')
class Group(models.Model):
name = models.CharField(max_length = 20)
class Membership(models.Model):
member = models.ForeignKey('Member')
group = models.ForeignKey('Group')
join_date = models.DateTimeField()
serializers.py:
imports...
class MemberSerializer(ModelSerializer):
class Meta:
model = Member
class GroupSerializer(ModelSerializer):
class Meta:
model = Group
views.py:
imports...
class MemberViewSet(ModelViewSet):
queryset = Member.objects.all()
serializer_class = MemberSerializer
class GroupViewSet(ModelViewSet):
queryset = Group.objects.all()
serializer_class = GroupSerializer
When GETing an instance of Member, I successfully receive all of the member's fields and also its groups - however I only get the groups' details, without extra details that comes from the Membership model.
In other words I expect to receive:
{
'id' : 2,
'name' : 'some member',
'groups' : [
{
'id' : 55,
'name' : 'group 1'
'join_date' : 34151564
},
{
'id' : 56,
'name' : 'group 2'
'join_date' : 11200299
}
]
}
Note the join_date.
I have tried oh so many solutions, including of course Django Rest-Framework official page about it and no one seems to give a proper plain answer about it - what do I need to do to include these extra fields? I found it more straight-forward with django-tastypie but had some other problems and prefer rest-framework.

How about.....
On your MemberSerializer, define a field on it like:
groups = MembershipSerializer(source='membership_set', many=True)
and then on your membership serializer you can create this:
class MembershipSerializer(serializers.HyperlinkedModelSerializer):
id = serializers.Field(source='group.id')
name = serializers.Field(source='group.name')
class Meta:
model = Membership
fields = ('id', 'name', 'join_date', )
That has the overall effect of creating a serialized value, groups, that has as its source the membership you want, and then it uses a custom serializer to pull out the bits you want to display.
EDIT: as commented by #bryanph, serializers.field was renamed to serializers.ReadOnlyField in DRF 3.0, so this should read:
class MembershipSerializer(serializers.HyperlinkedModelSerializer):
id = serializers.ReadOnlyField(source='group.id')
name = serializers.ReadOnlyField(source='group.name')
class Meta:
model = Membership
fields = ('id', 'name', 'join_date', )
for any modern implementations

I was facing this problem and my solution (using DRF 3.6) was to use SerializerMethodField on the object and explicitly query the Membership table like so:
class MembershipSerializer(serializers.ModelSerializer):
"""Used as a nested serializer by MemberSerializer"""
class Meta:
model = Membership
fields = ('id','group','join_date')
class MemberSerializer(serializers.ModelSerializer):
groups = serializers.SerializerMethodField()
class Meta:
model = Member
fields = ('id','name','groups')
def get_groups(self, obj):
"obj is a Member instance. Returns list of dicts"""
qset = Membership.objects.filter(member=obj)
return [MembershipSerializer(m).data for m in qset]
This will return a list of dicts for the groups key where each dict is serialized from the MembershipSerializer. To make it writable, you can define your own create/update method inside the MemberSerializer where you iterate over the input data and explicitly create or update Membership model instances.

I just had the same problem and I ended it up solving it with an annotation on the group queryset.
from django.db.models import F
class MemberSerializer(ModelSerializer):
groups = serializers.SerializerMethodField()
class Meta:
model = Member
def get_groups(self, instance):
groups = instance.groups.all().annotate(join_date=F(membership__join_date))
return GroupSerializer(groups, many=True).data
class GroupSerializer(ModelSerializer):
join_date = serializers.CharField(required=False) # so the serializer still works without annotation
class Meta:
model = Group
fields = ..., 'join_date']

NOTE: As a Software Engineer, I love to use Architectures and I have deeply worked on Layered Approach for Development so I am gonna be Answering it with Respect to Tiers.
As i understood the Issue, Here's the Solution
models.py
class Member(models.Model):
member_id = models.AutoField(primary_key=True)
member_name = models.CharField(max_length =
class Group(models.Model):
group_id = models.AutoField(primary_key=True)
group_name = models.CharField(max_length = 20)
fk_member_id = models.ForeignKey('Member', models.DO_NOTHING,
db_column='fk_member_id', blank=True, null=True)
class Membership(models.Model):
membershipid = models.AutoField(primary_key=True)
fk_group_id = models.ForeignKey('Group', models.DO_NOTHING,
db_column='fk_member_id', blank=True, null=True)
join_date = models.DateTimeField()
serializers.py
import serializer
class AllSerializer(serializer.Serializer):
group_id = serializer.IntegerField()
group_name = serializer.CharField(max_length = 20)
join_date = serializer.DateTimeField()
CustomModels.py
imports...
class AllDataModel():
group_id = ""
group_name = ""
join_date = ""
BusinessLogic.py
imports ....
class getdata(memberid):
alldataDict = {}
dto = []
Member = models.Members.objects.get(member_id=memberid) #or use filter for Name
alldataDict["MemberId"] = Member.member_id
alldataDict["MemberName"] = Member.member_name
Groups = models.Group.objects.filter(fk_member_id=Member)
for item in Groups:
Custommodel = CustomModels.AllDataModel()
Custommodel.group_id = item.group_id
Custommodel.group_name = item.group_name
Membership = models.Membership.objects.get(fk_group_id=item.group_id)
Custommodel.join_date = Membership.join_date
dto.append(Custommodel)
serializer = AllSerializer(dto,many=True)
alldataDict.update(serializer.data)
return alldataDict
You would technically, have to pass the Request to DataAccessLayer which would return the Filtered Objects from Data Access Layer but as I have to Answer the Question in a Fast Manner so i adjusted the Code in Business Logic Layer!