I have two models inheriting same model and i want to serialize them. I couldn't see a way to do it with modelserializer class.
class Answer(models.Model):
submission = models.ForeignKey( Submission, related_name='answers', on_delete=models.CASCADE)
question = models.ForeignKey( Question, related_name='answers', on_delete=models.CASCADE )
class TextAnswer(Answer):
answer = models.CharField(max_length=10000 , blank=True)
class IntegerAnswer(Answer):
answer = models.IntegerField(blank=True)
What i want to do is this so i can serialize all the related answers no matter what type they are.
class QuestionSerializer(serializers.ModelSerializer):
answers = AnswerSerializer(many=True)
class Meta:
model = Question
fields = '__all__'
One approach I can think of is to use SerializerMethodFields:
class QuestionSerializer(serializers.ModelSerializer):
answers = serializers.SerializerMethodField()
class Meta:
model = Question
fields = '__all__'
def get_answers(self, obj)
return obj.answers.all().values_list('answer', flat=True)
Related
I have two models in a 'many to many' relationship Video and Genre. I want to represent them in my API using the Django Rest Framework and with Hyperlinking. I have tried using the the nested relationships solution that I have found over the internet but it brings me an error for the list viewss eg genres/ and videos/ as described below.
models.py
class VideoGenre(models.Model):
video = models.ForeignKey(Video, on_delete=models.CASCADE, related_name='genres')
genres = models.ForeignKey(Genre, on_delete=models.CASCADE, related_name='videos')
class Meta:
unique_together = ['video', 'genre']
class Video(models.Model):
genres = models.ManyToManyField(Genre, related_name="videos", blank=True, through='VideoGenre')
title = serializers.CharField(default=serializers.CurrentUserDefault())
class Genre(models.Model):
name = models.CharField(max_length=20)
descr = models.CharField(max_length=255)
serializers.py
class GenreSerializer(serializers.HyperlinkedModelSerializer):
videos = serializers.HyperlinkedIdentityField(many=True, view_name="video-detail")
class Meta:
model = ku_api_models.Genre
fields = "__all__"
class VideoSerializer(serializers.HyperlinkedModelSerializer):
genres = GenreSerializer(source='genre_set', many=True, read_only=True)
class Meta:
model = ku_api_models.Video
fields = "__all__"
class VideoGenreSerializer(serializers.HyperlinkedModelSerializer):
video = serializers.ReadOnlyField(source='video.id')
genre = serializers.ReadOnlyField(source='genre.id')
class Meta:
model = ku_api_models.VideoGenre
fields = "__all__"
unique_together = ['video', 'genre']
views.py
class VideoDetailView(RetrieveUpdateDestroyAPIView):
parser_classes = (MultiPartParser,)
serializer_class = VideoSerializer
queryset = Video.objects.all()
def perform_update(self, serializer):
serializer.save(owner=self.request.user)
class VideoListView(ListCreateAPIView):
parser_classes = (MultiPartParser,)
serializer_class = VideoSerializer
queryset = Video.objects.all()
def perform_create(self, serializer):
serializer.save(owner=self.request.user)
class GenreListView(ListCreateAPIView):
serializer_class = GenreSerializer
queryset = Genre.objects.all()
class GenreDetailtView(RetrieveUpdateDestroyAPIView):
serializer_class = GenreSerializer
queryset = Genre.objects.all()
urls.py
path('videos/', views.VideoListView.as_view(), name='video-list'),
path('videos/<int:pk>', views.VideoDetailView.as_view(), name='video-detail'),
path('genres/', views.GenreListView.as_view(), name="genre-list"),
path('genres/<int:pk>', views.GenreDetailtView.as_view(), name="genre-detail"),
I am getting below exception on the browsable API renderer
Exception Type: ProgrammingError at /api/genres/
Exception Value: relation "ku_api_videogenre" does not exist
LINE 1: ..._video"."owner_id" FROM "ku_api_video" INNER JOIN "ku_api_vi...
I have looked into these below links as referred above
django rest framework serializing many to many field
many to many relationship through an intermidiate model
serializing many to many field
... and tried them but getting the same/almost the same, only different is the relation name that "does not exist"
What am I missing? How to make it right? Thanks
I have found a way to this:
Changes will be in the serializers.py
serializers.py
class VideoSerializer(serializers.HyperlinkedModelSerializer):
genres = serializers.HyperlinkedRelatedField(many=True, read_only=False, view_name='genre-detail', queryset=ku_api_models.Genre.objects.all())
class Meta:
model = ku_api_models.Video
#fields = ('url', 'id', 'datetime_added', 'title', 'video_file', 'owner')
fields = "__all__"
def create(self, validated_data):
genres = validated_data.pop('genres', [])
video_instance = ku_api_models.Video.objects.create(**validated_data)
video_instance.genres.set(genres)
return video_instance
def update(self, instance, validated_data):
genres = validated_data.pop('genres', [])
instance.genres.set(genres)
instance.save()
return instance
class VideoGenreSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = ku_api_models.VideoGenre
fields = "__all__"
class GenreSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = ku_api_models.Genre
fields = "__all__"
Source: Docs: intermediary-manytomany
I have two models and two serializers. I'm trying to use a property from one this models.
I already tried using foo = serializers.ReadOnlyField() but doesn't work.
My example:
class ExampleOne(models.Model):
example_three = models.ForeignKey(
"foo.ExampleThree",
on_delete=models.CASCADE,
related_name="ones",
)
#property
def foo(self):
return bar
class ExampleTwo(models.Model):
example_four = models.ForeignKey(
"foo.ExampleFour",
on_delete=models.CASCADE,
related_name="twos",
)
class ExampleThree(models.Model):
example_four = models.ForeignKey(
"foo.ExampleFour",
on_delete=models.CASCADE,
related_name="threes",
)
class ExampleFour(models.Model):
...
fields=...
...
class ExampleOneSerializer(serializers.Serializer):
class Meta:
model = ExampleOne
fields = "__all__"
class ExampleTwoSerializer(serializers.Serializer):
foo = serializers.ReadOnlyField()
class Meta:
model = ExampleTwo
fields = "__all__"
Does anyone have any idea how I can get this porperty from another serializer?
I have model
class A(models.Model):
is_enable = models.BooleanField(default=False)
title = models.CharField(max_length=255, blank=True, null=True)
updated_date = models.DateTimeField(auto_now=True)
show_count = models.IntegerField(default=0)
answers_count = models.IntegerField(default=0)
audience = JSONField()
events = JSONField()
rules = JSONField()
message = models.TextField(blank=True)
#property
def conversion(self):
if self.show_count == 0:
return 0.0
return (self.answers_count / self.show_count) * 100
And i have serializer
class ASerializer(serializers.ModelSerializer):
audience = serializers.JSONField()
events = serializers.JSONField()
rules = serializers.JSONField()
class Meta:
model = Trigger
fields = '__all__'
I want to add to response #property conversion` field
and I want to do something like this in serializer
class Meta:
model = Trigger
fields = '__all__' + conversion
I know that i can make something like this
class Meta:
model = Trigger
fields = ('is_enable', 'title' ... 'conversion')
But i want add all fields and conversion field and do this more beautiful
you can use somethig like this:
class ModelMixin:
#classmethod
def _get_model_fields(cls):
all_fields = cls._meta.get_fields()
fields = [i.name for i in all_fields if i.__class__.__name__ not in ['ManyToManyRel', 'GenericRelation', 'ManyToOneRel']]
return fields
#classmethod
def get_serializer_fields(cls):
fields = cls._get_model_fields()
return fields
class A(ModelMixin, models.Model):
...
class ASerializer(ModelSerializer):
custom_field = serializers.JSONField()
class Meta:
model = A
fields = A.get_serializer_fields()
fields.append('cusom_field')
Might still not be as clean as you want it to be, but using <model>._meta.fields you can get all fields of that model, and using the name property of each field you can retrieve the names that refer to them.
As the serializers file is interpreted as python, it supports code execution, meaning you can use all python functionalities when setting properties, including a for loop, which gives us the ability to do this:
fields = (tuple((f.name for f in A._meta.fields)) + ('conversion',))
Needed this for my own model as well and there it seemed to work, so hopefully so does it for you.
You can create a SerializerMethodField in your serializer and later define a method in serializer itself that can call your functions you defined in models using #property
class ASerializer(serializers.ModelSerializer):
audience = serializers.JSONField()
events = serializers.JSONField()
rules = serializers.JSONField()
conversion = serializers.SerializerMethodField()
class Meta:
model = Trigger
fields = '__all__'
def get_conversion(self,obj):
return obj.conversion
This should allow you to keep your code beautiful without modifying much of your code.
# models.py
class Student(models.Model):
name = models.CharField( max_length=256)
student_numer = models.CharField(max_length=256)
teachers = models.ManyToManyField(Teacher)
class Teacher(models.Model):
name = models.CharField(max_length=256)
# serializers.py
class StudentSerializer(serializers.ModelSerializer):
class Meta:
model = Student
fields = ('name', 'student_number', )
class TeacherSerializer(serializers.ModelSerializer):
students = StudentSerializer(many=True)
class Meta:
model = Teacher
fields = '__all__'
def update(self, instance, validated_data):
students = validated_data.pop('students')
# here I want delete all old students, and add all new students
# of course, I have more better way to update it, but here just for simple.
But in fact, if I update teacher instance, and if the students not change, it will
raise: student with this student_numer already exist.
I know why, because StudentSerializer's student_numer field has the validator check unique.
And I can add some code like this to fixed this problem:
class StudentSerializer(serializers.ModelSerializer):
class Meta:
model = Student
fields = ('name', 'student_number', )
extra_kwargs = {
'student_numer': {
'validators':[]
}
}
Now I want to know is there any more better way ??
I'm trying to serialize a model containing a property field that I also want to serialize.
models.py:
class MyModel(models.Model):
name = models.CharField(max_length=100)
slug = models.AutoSlugField(populate_from='name')
#property
def ext_link(self):
return "/".join([settings.EXT_BASE_URL, self.slug])
serializers.py:
class MyModelSerializer(serializers.ModelSerializer):
class Meta:
model = MyModel
fields = ('name', 'ext_link')
When trying to get to the related URL, I'm getting a serializer exception (KeyError) on the ext_link property.
How can I serialize the ext_link property?
Because it's not a model field, it needs to be added explicitly to the serializer class
class MyModelSerializer(serializers.ModelSerializer):
ext_link = serializers.Field()
class Meta:
model = MyModel
fields = ('name', 'ext_link')
as #Robert Townley's comment, this work with version 3.8.2:
class MyModelSerializer(serializers.ModelSerializer):
ext_link = serializers.ReadOnlyField()
class Meta:
model = MyModel
fields = "__all__"
The accepted answer doesn't seem to work for me, nor does the ReadOnlyField.
However, I have had success when I use a field that corresponds to the return type of my property function.
So for the example, I would do this:
class MyModelSerializer(serializers.ModelSerializer):
ext_link = serializers.CharField()
class Meta:
model = MyModel
fields = ('name', 'ext_link')
I've been able to do this with ListField, DictField, and IntegerField as well.
Another thing you might want to do is add a property that its contents are not a string. Let's say you have a model called Person and another one called Food that look like this (we assume that each food is the favorite of only one person, making it a OneToMany connection):
class Person(models.Model):
name = models.CharField(max_length=255)
#property
def favorite_foods(self):
return Food.objects.filter(person=self.pk)
class Food(models.Model):
name = models.CharField(max_length=255)
persons_favorite = models.ForeignKey(Person, on_delete=models.CASCADE)
If you want to add favorite_foods in Person's serializer all you have to do is:
class PersonSerializer(serializers.ModelSerializer):
favorite_foods = FoodSerializer(read_only=True, many=True)
class Meta:
model = Person
fields = ('name', 'favorite_foods')