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How to create nested serialization from mutliple models uisng django rest framewrok

I am trying to create nested relationship from more than two models in Django Rest Framework.
Thank you in advance for helping me.
I succeed with two models but when I'm trying with three models unable to create nested serialization.
from django.db import models
class Project(models.Model):
project_id = models.AutoField(primary_key=True)
project_name = models.CharField(max_length=255)
def __str__(self):
return self.name
class Site(models.Model):
site_id = models.AutoField(primary_key=True)
site_name = models.CharField(max_length=255)
project_id= models.ForeignKey(Project, related_name="projectid", on_delete=models.CASCADE)
def __str__(self):
return self.site_name
class Aggin(models.Model):
assign_id = models.AutoField(primary_key=True)
site_id = Models.ForeginKey(Site, relate_name="siteid", on_delete=models.CASCADE)
from rest_framework import serializers
from .models import Song, Artist
class ProjectSerializer(serializers.ModelSerializer):
class Meta:
model = Project
fields = ('__all__')
class SiteSerializer(serializers.ModelSerializer):
class Meta:
model = Site
fields = ('__all__')
class AggignSerializer(serializers.ModelSerializer)
class Meta:
model = Aggin
fields = ('__all__')

I think you don't need to primary id field if you wanna use the Django's default foreign key setting. And related_name should be defined from the view of the counterpart model.
from django.db import models
class Project(models.Model):
project_name = models.CharField(max_length=255)
def __str__(self):
return self.name
class Site(models.Model):
site_name = models.CharField(max_length=255)
project = models.ForeignKey(Project, related_name="sites", on_delete=models.CASCADE)
def __str__(self):
return self.site_name
class Aggin(models.Model):
site = Models.ForeginKey(Site, relate_name="assigns", on_delete=models.CASCADE)
And then, in serializer, you can set like the following.
from rest_framework import serializers
from .models import Song, Artist
class ProjectSerializer(serializers.ModelSerializer):
sites = SiteSerializer(read_only = True, many = True)
class Meta:
model = Project
fields = ('id', 'project_name', 'sites')
class SiteSerializer(serializers.ModelSerializer):
assigns = AggignSerializer(read_only = True, many = True)
class Meta:
model = Site
fields = ('id', 'site_name', 'assigns')
class AggignSerializer(serializers.ModelSerializer):
class Meta:
model = Aggin
fields = ('id')

Showing extra field on ManyToMany relationship in Django serializer

I have a ManyToMany field in Django, like this:
class Dictionary(models.Model):
traditional = models.CharField(max_length=50)
simplified = models.CharField(max_length=50)
pinyin_numbers = models.CharField(max_length=50)
pinyin_marks = models.CharField(max_length=50)
translation = models.TextField()
level = models.IntegerField()
frequency = models.IntegerField()
idiom = models.BooleanField()
child_char = models.ManyToManyField('Dictionary', through='DictionaryChildChar', null=True)
class Meta:
db_table = 'dictionary'
indexes = [
models.Index(fields=['simplified', ]),
models.Index(fields=['traditional', ]),
]
class DictionaryChildChar(models.Model):
class Meta:
db_table = 'dictionary_child_char'
from_dictionary = models.ForeignKey(Dictionary, on_delete=models.CASCADE, related_name="from_dictionary")
to_dictionary = models.ForeignKey(Dictionary, on_delete=models.CASCADE, related_name="to_dictionary")
word_order = models.IntegerField()
Currently, I have a serializer like this:
class FuzzySerializer(serializers.ModelSerializer):
pinyin = serializers.CharField(
required=False, source="pinyin_marks")
definition = serializers.CharField(
required=False, source="translation")
hsk = serializers.CharField(required=False, source="level")
class Meta:
model = Dictionary
fields = ["id", "simplified", "pinyin", "pinyin_numbers","definition", "hsk", "traditional", "child_char"]
depth = 1
This gives me a dictionary entry, as well as the child dictionary entries associated with it (as a Chinese word is made up of several Chinese characters)
However, I need to know what order these child characters are in, and hence why I have word_order.
I would like this word_order field to appear on the individual child_char - how do I write my serializer in such a way that this additional field is present? Would I need to make a separate serializer for child_char?
EDIT: I have tried this serializer, it doesn't work:
class FuzzyChildCharSerializer(serializers.ModelSerializer):
class Meta:
model = DictionaryChildChar
fields = ["word_order"]

Easiest way is to create a dedicated FuzzyChildCharSerializer and then connect it to your original serializer as a nested relationship:
class FuzzyChildCharSerializer():
class Meta:
model = DictionaryChildChar
fields = ["word_order"] # And whatever other fields you want
class FuzzySerializer():
child_char = FuzzyChildCharSerializer(many=True)
...
You could also write a SerializerMethodField.

It appears I had to bridge the connection via the glue table, which makes sense.
class FuzzyChildCharSerializer(serializers.ModelSerializer):
pinyin = serializers.CharField(
required=False, source="pinyin_marks")
definition = serializers.CharField(
required=False, source="translation")
hsk = serializers.CharField(required=False, source="level")
class Meta:
model = Dictionary
fields = ["id", "simplified", "pinyin", "pinyin_numbers","definition", "hsk", "traditional",]
class FuzzyChildCharSerializerGlue(serializers.ModelSerializer):
to_dictionary = FuzzyChildCharSerializer()
class Meta:
model = DictionaryChildChar
fields = '__all__'
class FuzzySerializer(serializers.ModelSerializer):
pinyin = serializers.CharField(
required=False, source="pinyin_marks")
definition = serializers.CharField(
required=False, source="translation")
hsk = serializers.CharField(required=False, source="level")
from_dictionary = FuzzyChildCharSerializerGlue(many=True)
class Meta:
model = Dictionary
fields = ["id", "simplified", "pinyin", "pinyin_numbers","definition", "hsk", "traditional", "from_dictionary"]
depth = 1
This provides each character with its given word order

Lack of data with serialization model with ManyToManyField

Here's are examples I have:
models.py:
class Example(models.Model):
title = models.CharField(...)
description = models.CharField(...)
class Foo(models.Model):
example = models.ManyToManyField(Example)
serializers.py:
class FooSerializer(serializers.ModelSerializer):
class Meta:
model = Foo
fields = '__all__'
depth = 1
views.py:
...
serialized_data = [FooSerializer(foo).data for foo in Foo.objects.all().get]
In output, I receive only Example's IDs, but is there any way I could get title and description fields also (details of m2mfield)? As I understand, Foo.objects.all().get simply doesn't contain this data, but maybe I could somehow get it and use it?
I could also rebuild models if needed, but currently I use m2mf because of needs to contain multiple objects as related to this model data.
update
models.py:
class Event(models.Model):
ts = models.BigIntegerField(editable=False)
class Foo(Event):
user = models.ForeignKey(User, ...)
example = *...(remains to be the same)*
foos = models.ForeignKey('self', **somemore** null=True)
serializers.py:
class EventSerializer(serializers.ModelSerializer):
class Meta:
model = Event
fields = '__all__'
def to_representation(self, instance):
result = {'ts': instance.ts}
if isinstance(instance, Foo):
result['foo'] = FooSerializer(instance).data
return result
class UserSerializer(serializers.ModelSerializer):
class Meta:
model = User
fields = ('id', 'username')
class FooSerializer(serializers.ModelSerializer):
# user = UserSerializer(read_only=True) # with this I have an error: Got AttributeError when attempting to get a value for field 'username' on #serializer 'UserSerializer'
class Meta:
model = Foo
fields = '__all__'
depth = 1

You could use depth attribute to achieve desired output.
The default ModelSerializer uses primary keys for relationships, but
you can also easily generate nested representations using the depth
option.The depth option should be set to an integer value that
indicates the depth of relationships that should be traversed before
reverting to a flat representation.
class FooSerializer(serializers.ModelSerializer):
class Meta:
model = Foo
fields = '__all__'
depth = 1
Apart from the answer, I would like to change your views.py code, cause it seems like very bad :(. Do it on DRF Way as
serialized_data = FooSerializer(Foo.objects.all(), many=True).data<br>
Example View
from rest_framework.viewsets import ModelViewSet
class FooViewset(ModelViewSet):
serializer_class = FooSerializer
queryset = Foo.objects.all()
UPDATE-1
class UserSerializer(serializers.ModelSerializer):
class Meta:
model = User
exclude = ('password',) # add fields that are need to be excluded
class FooSerializer(serializers.ModelSerializer):
user = UserSerializer()
class Meta:
model = Foo
fields = '__all__'
depth = 1
depth = 1 will serializer all fields in the model, (It's same as setting the fields=='__all__' in Meta class of serializer)
UPDATE-2
class FooSerializer(serializers.ModelSerializer):
user = UserSerializer()
class Meta:
model = Foo
fields = '__all__'
depth = 1
def to_representation(self, instance):
real_data = super().to_representation(instance).copy()
# DO YOUR EXTRA CHECKS
child = UserSerializer(instance.child_foo).data
if child:
real_data.update({"child_data": child})
# After your checks, add it to "real_data"
return real_data
and I assumed I have a Foo model as
class Foo(models.Model):
example = models.ManyToManyField(Example)
user = models.ForeignKey(User)
child_foo = models.ForeignKey('self', null=True, blank=True)

In your serializer add depth = 1. Example where 'users' is the related field:
FooSerializer(serializers.ModelSerializer):
class Meta:
model = Foo
fields = ('id', 'account_name', 'users', 'created')
depth = 1

Dynamic choices in Foreignkey Field in Django Rest Framework

I have just started learning Django Rest Framework and trying to make a simple API using Django rest Framework.
This is my models.py
from __future__ import unicode_literals
from django.db import models
class Student(models.Model):
created = models.DateTimeField(auto_now_add=True)
name = models.CharField(max_length=150, blank=False)
student_id = models.CharField(max_length=20, primary_key=True)
father_name = models.CharField(max_length=150)
mother_name = models.CharField(max_length=150)
class Meta:
ordering = ('student_id',)
class Subject(models.Model):
created = models.DateTimeField(auto_now_add=True)
subject_id = models.CharField(max_length=20, primary_key=True)
name = models.CharField(max_length=150)
class Meta:
ordering = ('subject_id',)
class Result(models.Model):
created = models.DateTimeField(auto_now_add=True)
grade = models.DecimalField(max_digits=5, decimal_places=3, blank=False)
student_id = models.ForeignKey(Student, on_delete=models.CASCADE)
subject_id = models.ForeignKey(Subject, on_delete=models.CASCADE)
class Meta:
ordering = ('created',)
And this is my serializers.py
from rest_framework import serializers
from models import *
class StudentSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Student
fields = ('student_id', 'name', 'father_name', 'mother_name')
class SubjectSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Subject
fields = ('subject_id', 'name')
class ResultSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Result
fields = ('grade', 'student_id', 'subject_id')
In my "Result" model, I have two foreign keys; student_id and subject_id. This is how it looks like:
My questions is, how can I show the "name" field in the drop down menu in stead of showing "Student Object" and "Subject Object"?
I have tried with
STUDENT_CHOICES = [(each.student_id, each.name) for each in Student.objects.all()]
SUBJECT_CHOICES = [(each.subject_id, each.name) for each in Subject.objects.all()]
in the model's "choices=" field but it didn't work out.
Thanks in advance.

I think you're looking for this part of the DRF documentation.
Basically, your Django model's own representation is used. So for example, in your Student model you can add __str__ method:
# this is for Python 3, use __unicode__ on Python 2
def __str__(self):
return self.name
Meta options documentation for Django is here, look for model methods.

Django Rest Serializer get data related through Foreign Keys

I have the following model skeletons:
class A(models.Model):
post_id = models.ForeignKey('D')
user_id = models.ForeignKey('B')
class B(AbstractBaseUser):
email = models.EmailField(unique=True)
username = models.CharField(max_length=20, unique=True)
first_name = models.CharField(max_length=40)
last_name = models.CharField(max_length=40)
# `resource_id`
profile_photo = models.ForeignKey('C', null=True)
class C(models.Model):
user_id = models.ForeignKey('B')
name = models.CharField(max_length=60)
I want to write a serializer for A which should return name from model C, which is related to B.
The relation here is like
A->B->C
Now using A's serializer I want data to be fetched from C
I want to access C via A i.e get profile_photo from B and the get the name of profile_photo from C
I scrolled through RelatedFields as given here Django Rest relations but am not able to achieve what I want.
Is their any way I can achieve it.
Also there are a lot of fields other than mentioned in the model skeleton and I do not want to fetch those.
EDIT:
The final result I need is the all the user_id for a particular post_id from A with the name from model C

You can do this with a ModelSerializer:
Note: I will asumme that 'posts.Post' is model C
class CsSerializer(serializers.ModelSerializer):
class Meta:
model = C
fields = ('name')
class AsSerializer(serializers.ModelSerializer):
post_id = CsSerializer()
class Meta:
model = A
# exclude = ('field_you_dont_want_1', 'field_you_dont_want_2')
# fields = ('field_you_want_1', 'field_you_want_2')
Note that in CsSerializer you can return any field you want from model C in this case I'm just returning a name.
If you just need a string, you could use StringRelatedField
class AsSerializer(serializers.ModelSerializer):
post_id = serializers.StringRelatedField(many=True)
class Meta:
model = A
This StringRelatedField will return what C models return in __unicode__ method (__str__ method if python 3.x).
EDIT
Now, from your comment, I know that 'posts.Post' is not C model. So you could use SerializerMethodField:
class AsSerializer(serializers.ModelSerializer):
c_name = serializers.SerializerMethodField()
def get_c_name(self, obj):
return obj.user_id.c_set.values('name') # this will return a list of dicts with B's related C objects.
class Meta:
model = A
EDIT
You can always define class methods in your models:
class B(AbstractBaseUser):
email = models.EmailField(unique=True)
username = models.CharField(max_length=20, unique=True)
first_name = models.CharField(max_length=40)
last_name = models.CharField(max_length=40)
# `resource_id`
profile_photo = models.ForeignKey('C', null=True)
def get_profile_photo(self):
return self.profile_photo.name # This will return 'C' related object's name
So when you have an A's objects:
a_object.user_id.get_profile_photo()
Or if you have an B's object:
b_object.get_profile_photo()
EDIT
You can define a new Serializer for C class:
class CsSerializer(serializers.Serializer):
class Meta:
model = C
Then in your AsSerializer
class AsSerializer(serializers.ModelSerializer):
c_name = serializers.SerializerMethodField()
def get_c_name(self, obj):
qs = obj.user_id.c_set.all()
qs_serialized = CsSerializer(qs, many=True)
return qs_serialized.data
class Meta:
model = A