I have two serializers, one of which is nested:
class PaperSerializer(serializers.ModelSerializer):
class Meta:
model = Paper
class AuthorSerializer(serializers.ModelSerializer):
papers = PaperSerializer(
many=True,
read_only=True,
source='paper_set'
)
class Meta:
model = Author
I want to get a list of Authors which shows only their published Papers (Boolean field exists on the model).
I would like to call the API like /api/v1/authors/?show_published_only=true.
After some digging around, I discovered that you can pass the context from the ViewSet to the Serializer:
views.py
class AuthorViewSet(viewsets.ModelViewSet):
queryset = Author.objects.all()
serializer_class = AuthorSerializer
filter_fields = (
'show_published_only',
)
def get_serializer_context(self):
return {'request': self.request}
Now, create a new serializer FilteredPaperSerializer which inherits from serializers.ListSerializer, then override the to_representation() method to filter the queryset:
serializers.py
class FilteredPaperSerializer(serializers.ListSerializer):
def to_representation(self, data):
# Get the parameter from the URL
show_published_only = self.context['request'].query_params['show_published_only']
data = data.filter(is_published=show_published_only)
return super(FilteredPaperSerializer, self).to_representation(data)
class AuthorSerializer(serializers.ModelSerializer):
papers = FilteredPaperSerializer(
many=True,
read_only=True,
source='paper_set'
)
class Meta:
model = Author
NB: Don't forget to convert the fetched URL parameter to a Boolean or relevant data type for your model, I neglected to do it in the write-up above.
Related
I am new to DRF. I want to get saved the model.
In models.py, PackageDetails and PhysicalDetail have foreignkey relationship to Member
My serializers.py is as follows:
from rest_framework import serializers
from .models import Member, PackageDetails, PhysicalDetail
class PackageDetailsSerializer(serializers.ModelSerializer):
is_expired = serializers.SerializerMethodField()
members_expiry_date = serializers.SerializerMethodField()
class Meta:
model = PackageDetails
exclude = ['id']
extra_fields = ['is_expired', 'members_expiry_date']
def get_is_expired(self, instance):
return instance.is_expired
def get_members_expiry_date(self, instance):
return instance.members_expiry_date
class PhysicalDetailSerializer(serializers.ModelSerializer):
class Meta:
model = PhysicalDetail
exclude = ['id']
class MemberSerializer(serializers.ModelSerializer):
physical_details = PhysicalDetailSerializer(many=True)
package_details = PackageDetailsSerializer(many=True)
class Meta:
model = Member
fields = '__all__'
extra_fields = ['physical_details', 'package_details']
def create(self, validated_data):
physical_detail_data = validated_data.pop("physical_details")
package_detail_data = validated_data.pop("package_details")
member = Member.objects.create(**validated_data)
PhysicalDetail.objects.create(member=member, **physical_detail_data)
PackageDetails.objects.create(member=member, **package_detail_data)
return member
views.py :
class MemberViewset(viewsets.ModelViewSet):
queryset = Member.objects.all()
serializer_class = MemberSerializer
class PackageDetailViewset(viewsets.ModelViewSet):
queryset = PackageDetails.objects.all()
serializer_class = PackageDetailsSerializer
class PhysicalDetailViewset(viewsets.ModelViewSet):
queryset = PhysicalDetail.objects.all()
serializer_class = PhysicalDetailSerializer
In GET request it worked well.. but in POST request with the same json format it responses the following:
{
"physical_details": [
"This field is required."
],
"package_details": [
"This field is required."
]
}
I've provided the fields.. so why this happening..
You removed those from dict using pop()
The pop() method removes and returns an element from a dictionary having the given key.
Try using get() instead
The get() method returns the value for the specified key if the key is in the dictionary.
I want to pass user_id from view to serializer
I have model Answer
class Answer(models.Model) :
text = models.CharField(max_length=500)
question_id = models.CharField(max_length=25)
user_id = models.CharField(max_length=25, default=1)
This is my Serializer
class CreateAnswer(generics.CreateAPIView) :
def get_serializer_context(self):
context = super().get_serializer_context()
context["id"] = self.request.user.id
return context
serializer_class = AnswerQuestionSerializer
queryset = Answer.objects.all()
What I need to write in my view to take user_id and create model with this user_id ?
You can override the perform_create method & pass the user_id field to save method of the serializer.
class CreateAnswerView(generics.CreateAPIView) :
serializer_class = AnswerQuestionSerializer
def perform_create(self, serializer):
serializer.save(user_id=self.request.user.id)
You can use serializers.Hiddenfield to get current user in serializer class
https://www.django-rest-framework.org/api-guide/fields/#hiddenfield
There are multiple ways to do this task. One of them is to override create in your serializer.
Following is the code snippet:
class BlogSerializer(serializers.Serializer):
def create(self, validated_data):
user = self.context['request'].user
blog = Blog.objects.create(
user=user,
**validated_data
)
return blog
Explanation: A context is passed to the serializer which contains the request by default. So you can access the user easily with self.context['request'].user
For example i have a few models:
class Parent(Model):
api_key = CharField(max_length=250)
class Child(Model):
parent = ForeignKey(Parent, related_name='children')
status = CharField(max_length=250)
I wrote view based on ListAPIView, and serializer:
class ChildSerializer(ModelSerializer):
class Meta:
fields = ['id']
I need to take all Children with parent by find Parent by api_key and return this as:
{
children:[
{'id':1},
{'id':2}
]}
But i take this:
[
{'id':1},
{'id':2}
]
Well, you can define a ParentSerializer which will also return the child objects data with it:
class ParentSerializer(ModelSerializer):
child = ChildSerializer(many=True)
class Meta:
fields = ['api_key', 'child']
Then you need to find the parent by api_key and pass the Parent object to this serializer. Like this:
class ParentView(RetrieveAPIView):
queryset = Parent.objects.all()
lookup_field = 'api_key'
serializer_class = ParentSerializer
lookup_url_kwarg = 'api_key'
Finally set the url to:
path('/parent/<str:api_key>/', ParentView.as_view(), name='parent-detail')
Update
If you need to get the data from request.GET(url querystring), then it much simpler. Try like this:
class ParentView(ListAPIView):
queryset = Parent.objects.all()
serializer_class = ParentSerializer
def get_queryset(self, *args, **kwargs):
queryset = super().get_queryset(*args, **kwargs)
api_key = request.GET.get('api_key')
if api_key:
return queryset.filter(api_key=api_key)
return queryset
Trying to get a manytomany relationship in django but I'm getting the following error -
Got AttributeError when attempting to get a value for field name on serializer GenreSerializer.
The serializer field might be named incorrectly and not match any attribute or key on the Movie instance.
Original exception text was: 'Movie' object has no attribute 'name'.
There is a similar answer here recommending setting many=True, but it doesn't work -
Attribute error when attempting to get a value for field
models.py
class Genre(models.Model):
name = models.CharField(max_length=255,unique=True)
def __unicode__(self):
return self.name
class Movie(models.Model):
mname = models.CharField(max_length=255)
genres = models.ManyToManyField(Genre,related_name='movies')
def __unicode__(self):
return self.mname
serializers.py
class GenreSerializer(serializers.ModelSerializer):
class Meta:
model = Genre
fields = ('name','id')
class MovieSerializer(serializers.ModelSerializer):
genres = GenreSerializer(many=True, read_only=True)
class Meta:
model = Movie
fields = ('id','genres','mname')
urls.py
urlpatterns = [
url(r'^genres/$', views.GenreList.as_view()),
url(r'^genres/(?P<pk>[0-9]+)$', views.GenreDetail.as_view()),
]
urlpatterns = format_suffix_patterns(urlpatterns)
views.py
class GenreList(generics.ListCreateAPIView):
queryset = Genre.objects.all()
serializer_class = GenreSerializer
class GenreDetail(generics.RetrieveUpdateDestroyAPIView):
serializer_class = GenreSerializer
def get_queryset(self):
genres = Genre.objects.get(pk=self.kwargs.get('pk', None))
movies = Movie.objects.filter(genres=genres)
return movies
If yout are using a function based serializer, and wanted to fetch all the information of the ModelSerializer. Then use many=True
#api_view()
def movie_list(request):
movies = Movie.objects.all()
serializer = MovieSerializer(movies)
print(serializer)
return Response(serializer.data)
For the above code, the response was
Got AttributeError when attempting to get a value for field name on
serializer MovieSerializer. The serializer field might be named
incorrectly and not match any attribute or key on the QuerySet
instance. Original exception text was: 'QuerySet' object has no
attribute 'name'.
If we just add many=True in serializer = MovieSerializer(movies, many=True)`:
#api_view()
def movie_list(request):
movies = Movie.objects.all()
serializer = MovieSerializer(movies, many=True)
print(serializer)
return Response(serializer.data)
Then the output we get is
Similar to your other question, you are using the incorrect serializer on your GenreDetail view. You need to add the serializer for the type of models you are returning from get_queryset:
class GenreDetail(generics.RetrieveUpdateDestroyAPIView):
serializer_class = MovieSerializer
def get_queryset(self):
genres = Genre.objects.get(pk=self.kwargs.get('pk', None))
movies = Movie.objects.filter(genres=genres)
return movies
Let just take a simple example model in which you have three fields
from django.db import models
class Movie(models):
name = models.CharField()
description = models.TextField()
created = models.DateTimeField(auto_now_add=True)
If you're using this in serializer field then you have to pass argument "many=true" along with model name for example
movie = Movie.objects.all()
serializer = MovieSerializer(movie, many=True)
this is caused because when you have more than one objects(fields) in your model and you want to loop through every field for that we use "many=True"
I can't have object by its id in Django Rest Framework. I have a such model:
class BlogPost(models.Model):
title = models.CharField(max_length=128)
content = models.TextField()
created = models.DateTimeField(auto_now_add=True)
Then I write a serializer:
class BlogPostSerializer(serializers.ModelSerializer):
class Meta:
model = BlogPost
fields = ('title', 'content', 'created')
In my views.py I have this:
class BlogPostListFilter(dajngo_filter.FilterSet):
blog_post_id = django_filters.NumerFilter(name = 'id')
class Meta:
model = BlogPost
fiields = ['blog_post_id']
class BlogPostList(generics.ListCreateAPIView):
queryset = BlogPost.objects.all()
serializer_class = BlogPostSerializer
permission_classes = (AllowAny,)
filter_class = BlogPostListFilter
paginate_by = 100
And such code in my urls:
url(r'^blogpost/$', ListCreateAPIView.as_view(model=BlogPost), name='blogpost-list'),
But when I write in browser http://example.com/blogpost/?blog_post_id=1 I have all objects
If you really want to use ListCreateAPIView. You need to make some changes:
urls.py:
url(r'^blogpost/(?P<post_id>\w+)$', views.BlogPostList.as_view(),name='blogpost-list'),
views.py
class BlogPostList(generics.ListCreateAPIView):
serializer_class = BlogPostSerializer
permission_classes = (AllowAny,)
filter_class = BlogPostListFilter
paginate_by = 100
def get_queryset(self):
queryset = BlogPost.objects.filter(pk=self.kwargs['post_id'])
return queryset
But I think that Django Rest Framework provides better Class Based Views for your use case, such as RetrieveAPIView. As far as I understand, it seems that you just want to get an object, and this generic view is for a list of objects.
In my case, I stumbled upon this question looking to access the object id while overriding a ModelViewSet's retrieve method. After some research and experimentation, I discovered that the object id is stored in a dictionary called self.kwargs in the 'pk' key.
I am using djangorestframework==3.11.0.
class MealItemViewSet(viewsets.ModelViewSet):
queryset =MyModel.objects.all()
serializer_class = serializers.MyModelSerializer
def retrieve(self, request, *args, **kwargs):
# The Primary Key of the object is passed to the retrieve method through self.kwargs
object_id = self.kwargs['pk']
I hope this answer helps another forlorn StackOverflow wanderer at some point!