rest_framework access objects of ManyToManyField in intermediate model - django-rest-framework

Question

I have a patient model. Each patient can have several "Medical Records" where choices come from models like "BodyPart" or "Medicin":
class Patient(models.Model):
name = models.CharField(max_length=200)
def __str__(self):
return self.name
class Examination(models.Model):
name = models.CharField(max_length=200)
def __str__(self):
return self.name
class BodyPart(models.Model):
name = models.CharField(max_length=200)
def __str__(self):
return self.name
class Medicin(models.Model):
name = models.CharField(max_length=200)
def __str__(self):
return self.name
class MedicalRecord(models.Model):
patient = models.ForeignKey('Patient', on_delete=models.CASCADE,)
examination = models.ForeignKey('Examination', on_delete=models.CASCADE)
part_of_body = models.ForeignKey('BodyPart', on_delete=models.CASCADE)
medicin = models.ManyToManyField('Medicin')
def __str__(self):
return self.patient.name
Using Inlines we can nicely add Records to each Patient:
class MedicalRecordAdmin(admin.TabularInline):
model = MedicalRecord
extra = 1
class PatientAdmin(admin.ModelAdmin):
model = Patient
inlines = [MedicalRecordAdmin,]
...
admin.site.register(Patient, PatientAdmin)
...
Where I'm failing is (already tried trough, serializers.StringRelatedField(many=True), etc.), how can I serialize these relations from the side of the Patient Model?
# view
class PatientViewSet(viewsets.ReadOnlyModelViewSet):
serializer_class = PatientSerializer
queryset = Patient.objects.all()
# serializer
class PatientSerializer(serializers.ModelSerializer):
class Meta:
model = Patient
fields = '__all__'
depth = 3
ends in:
[
{
"id": 1,
"name": "Bert"
}
]
## But I would expect something like:
[
{
"id": 1,
"name": "Bert",
"medical_records":[
[
{
"medicine": ["a","b","c"],
"body_part": "leg",
"examination": "x-ray"
}
],
[
{
"medicine": ["e","f","g"],
"body_part": "head",
"examination": "surgery"
}
],
]
}
]

Answer 1

You have to use a nested serializer and use source fields to achieve the desired result.
Nested relationships- DRF documentation
Somewhat like this :
class Patient(models.Model):
name = models.CharField(max_length=200)
def __str__(self):
return self.name
class Examination(models.Model):
name = models.CharField(max_length=200)
def __str__(self):
return self.name
class BodyPart(models.Model):
name = models.CharField(max_length=200)
def __str__(self):
return self.name
class Medicin(models.Model):
name = models.CharField(max_length=200)
def __str__(self):
return self.name
class MedicalRecord(models.Model):
patient = models.ForeignKey('Patient', on_delete=models.CASCADE, related_name='patient_med')
examination = models.ForeignKey('Examination', on_delete=models.CASCADE, related_name='examination_med')
part_of_body = models.ForeignKey('BodyPart', on_delete=models.CASCADE, relayted_name='part_of_body_med')
medicin = models.ManyToManyField('Medicin', related_name='medicin_med')
class MedicalRecordSerializer(serializers.ModelSerializer):
body_part = serializers.CharField(source='part_of_body.name', read_only=True)
examination = serializers.CharField(source='examination.name', read_only=True)
medicine = serializers.ListField(source='medicine.name', read_only=True)
class Meta:
model = MedicalRecord
fields = ('body_part', 'examination', 'medicine')
class PatientSerializer(serializers.ModelSerializer):
patient_med = MedicalRecordSerializer(many=True, read_only=True)
class Meta:
model = Patient
fields = '__all__'
depth = 3