# Django REST framework light includable serializer fields
## Requirements
* Python (2.7, 3.4, 3.5, 3.6)
* [Django REST Framework](https://github.com/encode/django-rest-framework) (>=3.0)
## Usage
serializers.py
```python
class GroupSerializer(SerializerIncludeMixin, ModelSerializer):
@classproperty # django.utils.decorators
def extra_objects(cls):
return {
'users': UserSerializer(source='user_set', many=True),
'active_users': UserSerializer(many=True),
}
class Meta:
model = Group
fields = ('id', 'name')
```
views.py
```python
class GroupViewSet(QueryOptimizerMixin, ReadOnlyModelViewSet):
"""
Groups.
list:
Available includable objects:
* users - all users;
* active_users - only active users.
"""
queryset = Group.objects.all()
serializer_class = GroupSerializer
select_related = {}
prefetch_related = {
'users': 'user_set',
'active_users': Prefetch(
lookup='user_set',
queryset=User.objects.filter(is_active=True),
to_attr='active_users',
),
}
```
And now we can to do that:
```python
client = APIClient()
response = client.get( # GET /groups/?include[]=active_users
'/groups/',
data=[
('include[]', 'active_users'),
],
)
```
This will make only 2 query:
* all groups
* prefetch only active users
# Documentation
## rest_framework_include_mixin.SerializerIncludeMixin
Used in any serializer to automatically replace and add serializer fields.
### `extra_objects` class variable
**key**:str - value from GET parameter `include[]`.
For example, `profile` for `/users/?include[]=profile`.
**value**:Serializer - any field serializer.
Example:
```python
class UserSerializer(SerializerIncludeMixin, ModelSerializer):
extra_objects = {
'profile': ProfileSerializer(),
'groups': GroupSerializer(many=True),
}
class Meta:
model = User
fields = ('id', 'profile_id')
```
| GET parameters | Result serializer fields |
|-------------------------------------|--------------------------------------------------------------------------------------------|
| | 'id': IntegerField(), 'profile_id': IntegerField() |
| ?include[]=profile | 'id': IntegerField(), 'profile': ProfileSerializer() |
| ?include[]=groups | 'id': IntegerField(), 'profile_id': IntegerField(), 'groups': GroupSerializer(many=True) |
| ?include[]=profile&include[]=groups | 'id': IntegerField(), 'profile': ProfileSerializer(), 'groups': GroupSerializer(many=True) |
*Note: standard serializer fields with/without `_id` will be replaced to field from `extra_objects`.*
*For `?include[]=profile`: `profile` and `profile_id` will be replaced to `profile` from `extra_objects`.*
## rest_framework_include_mixin.QueryOptimizerMixin
Used with ModelViewSet to optimize database queries.
### `select_related` class variable
**key**:str - value from GET parameter `include[]`.
**value**:str - field name that can be passed to select_related ([model manager function](https://docs.djangoproject.com/en/2.1/ref/models/querysets/#select-related)).
### `prefetch_related` class variable
**key**:str - value from GET parameter `include[]`.
**value**:Union[str, Prefetch] - field name or Prefetch object that can be passed to prefetch_related ([model manager function](https://docs.djangoproject.com/en/2.1/ref/models/querysets/#prefetch-related)).
