drf-nested-relations 0.0.2

An extension of django rest framework that allows writing nested relations

# DRF Nested Relations

This python package is an extension for django rest framework for creating, updating and deleting nested relations. The nested relations can go to `any depth`.

It receives nested data as list of dictionaries.
It works for generic relations and foreign keys for now.


* If the dictionary contains `id` field, the nested data will be updated.

* If the dictionary does not contain `id`, field , new data will be created.

* If the dictionary contains only `id` as key, the data will be deleted.

# Usage

### Models

```python
from django.db import models
from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation
from django.contrib.contenttypes.models import ContentType

class ContactData(models.Model):
content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE, blank=True, null=True)
object_id = models.PositiveIntegerField(blank=True, null=True)
content_object = GenericForeignKey()
phone = models.CharField(max_length=25,blank=True, null=True)
email = models.EmailField()

class Person(models.Model):
name = models.CharField(max_length=50)
contact_data = GenericRelation(ContactData, related_query_name='content_obj_person')

class Skill(models.Model):
name = models.CharField(max_length=50)
person = models.ForeignKey('Person', related_name='skills', on_delete=models.CASCADE)
````

### Serializers

```Python
from rest_framework import serializers
from nested_relations.serializers import NestedDataModelSerializer
from .models import ContactData, Person, Skill

class ContactDataSerializer(serializers.ModelSerializer):
class Meta:
model = ContactData
exclude = ('content_type', 'object_id')

class SkillSerializer(serializers.ModelSerializer):
class Meta:
model = Skill
exclude = ('person',)

class PersonSerializer(NestedDataModelSerializer):

contact_data = serializers.JSONField(required=False, allow_null=True)
skills = serializers.JSONField(required=False, allow_null=True)

class Meta:
model = Person
fields = '__all__'
nestedSerializer = {
'contact_data': {'serializer_class': ContactDataSerializer, 'many': True, 'kwargs': 'content_object'},
'skills':{'serializer_class': SkillSerializer, 'many': True, 'kwargs': 'person'}
}


```


* For generic relation ,
use `field_name = serializers.JSONField()` and same `field_name` in nested serializer. (An attribute in main model that points to nested relation)

* For foreign key,
Use `related_name = serializers.JSONField()` and same `related_name` in nested serializer. (An attribute in main model that points to nested relation)

* For both,
Provide `many=True`. The value for `kwargs` is clear from example. It is an attribute in nested relation that points to main model.

## Writing data
```python
# Creating a person

data = {
"contact_data": [{"email":"[e-mail]"},{"email":"[e-mail]"}, {"email":"[e-mail]"}],
"name": "Sagar"
}

person_serializer = PersonSerializer(data=data, context={'request':request})
person_serializer.is_valid(raise_exception=True)
person = person_serializer.save()
print(person_serializer.data)

{
"id": 3,
"contact_data": [
{
"id": 4,
"phone": null,
"email": "[e-mail]"
},
{
"id": 5,
"phone": null,
"email": "[e-mail]"
},
{
"id": 6,
"phone": null,
"email": "[e-mail]"
}
],
"skills": [],
"name": "Sagar"
}

# Updating the person
data = {
"id": 3,
"contact_data": [
{ # update
"id": 4,
"phone": null,
"email": "[e-mail]"
},
{ # delete
"id": 5
},
{ # create
"phone": null,
"email": "[e-mail]"
}
],
"skills": [],
"name": "Sagar"
}

person_serializer = PersonSerializer(person, data=data, context={'request':request})
person_serializer.save()
print(person_serializer.data)

{
"id": 3,
"contact_data": [
{
"id": 4,
"phone": null,
"email": "[e-mail]"
},
{ # no change
"id": 6,
"phone": null,
"email": "[e-mail]"
},
{
"id": 7,
"phone": null,
"email": "[e-mail]"
}
],
"skills": [],
"name": "Sagar"
}
```
## Deeper Relations
For deeper relations, the nested serializer should further inherit `NestedDataModelSerializer` and their corresponding nested serializers have to be provided.