Registry / web-framework / django-rest-polymorphic

django-rest-polymorphic

library0.1.10pypypi✓ verified 25d ago

django-rest-polymorphic is a Python library that provides polymorphic serializers for Django REST Framework. It enables you to easily define serializers for models that utilize inheritance through the django-polymorphic library. The current version is 0.1.10, and while its core functionality has been integrated into django-polymorphic, the standalone package is still available on PyPI.

web-framework serialization

pip install django-rest-polymorphic

github ↗package ↗

INSTALL

IMPORT

SIG · DJANGO-REST-POLYMO

django-rest-polymorphic

web-frameworkpythonv0.1.10

Install

3.9s avg

Import

862ms

Disk

71MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.1.10 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.906s · 71.4MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 3.9s · import 0.818s · 72MB

71MB installed

● package 71MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

PolymorphicSerializer

✓ from rest_polymorphic.serializers import PolymorphicSerializer

✗ from polymorphic.contrib.drf.serializers import PolymorphicSerializer

While this was the original import for django-rest-polymorphic, the core functionality (PolymorphicSerializer) has been incorporated into django-polymorphic itself. The recommended import path for new projects or migrations is now `from polymorphic.contrib.drf.serializers import PolymorphicSerializer`.

This quickstart demonstrates how to set up polymorphic models using `django-polymorphic`, define individual `ModelSerializer`s for each concrete type, and then create a `PolymorphicSerializer` to handle the mapping. Finally, it shows how to integrate this into a Django REST Framework `ViewSet` to expose a polymorphic API endpoint. You would then include this ViewSet in your Django project's `urls.py`.

from django.db import models from rest_framework import serializers, viewsets from polymorphic.models import PolymorphicModel from rest_polymorphic.serializers import PolymorphicSerializer # 1. Define polymorphic models using django-polymorphic class Project(PolymorphicModel): topic = models.CharField(max_length=30) class ArtProject(Project): artist = models.CharField(max_length=30) class ResearchProject(Project): supervisor = models.CharField(max_length=30) # 2. Define serializers for each concrete model class ProjectSerializer(serializers.ModelSerializer): class Meta: model = Project fields = ('topic', 'resource_type') # 'resource_type' is added automatically by PolymorphicSerializer class ArtProjectSerializer(serializers.ModelSerializer): class Meta: model = ArtProject fields = ('topic', 'artist', 'resource_type') class ResearchProjectSerializer(serializers.ModelSerializer): class Meta: model = ResearchProject fields = ('topic', 'supervisor', 'resource_type') # 3. Create a PolymorphicSerializer to map models to serializers class ProjectPolymorphicSerializer(PolymorphicSerializer): model_serializer_mapping = { Project: ProjectSerializer, ArtProject: ArtProjectSerializer, ResearchProject: ResearchProjectSerializer } # 4. Use the polymorphic serializer in a ViewSet class ProjectViewSet(viewsets.ModelViewSet): queryset = Project.objects.all() serializer_class = ProjectPolymorphicSerializer

Debug

Known issues

breakingThe core `PolymorphicSerializer` functionality has been incorporated directly into `django-polymorphic` (specifically at `polymorphic.contrib.drf.serializers.PolymorphicSerializer`). While `django-rest-polymorphic` still exists, the recommended approach for new projects or migrating existing ones is to switch imports.

fix

Change import statements from `from rest_polymorphic.serializers import PolymorphicSerializer` to `from polymorphic.contrib.drf.serializers import PolymorphicSerializer`.

affects: All versions, as this is a migration path recommendation for users of `django-polymorphic`'s built-in DRF support.

gotchaWhen extending `HyperlinkedModelSerializer` instead of `ModelSerializer`, you need to explicitly define `extra_kwargs` to direct the URL to the appropriate view for your polymorphic serializer. This ensures correct URL generation for specific child types.

fix

Add `extra_kwargs` to your child serializers' `Meta` class, for example: `extra_kwargs = {'url': {'view_name': 'drf:project-detail', 'lookup_field': 'pk'}}`.

affects: All versions

gotchaBy default, the polymorphic type is identified by a field named `resource_type`. If you need to use a different field name in your API requests/responses, you must override the `resource_type_field_name` attribute.

fix

Set `resource_type_field_name = 'your_custom_type_field'` on your `PolymorphicSerializer` subclass.

affects: All versions

gotchaUsing `django-polymorphic` (and consequently `django-rest-polymorphic`) for model inheritance can have performance implications. Each query to a base polymorphic model will result in `INNER JOIN` operations to fetch fields from subclassed models.

fix

Be mindful of performance for very deep inheritance hierarchies or extremely large datasets. Consider alternative inheritance strategies if performance becomes a critical bottleneck. Ensure appropriate database indexing.

affects: All versions (inherent to `django-polymorphic` design)

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'rest_polymorphic.serializers'

The core functionality of `django-rest-polymorphic` has been integrated into the `django-polymorphic` library itself, meaning the original `rest_polymorphic` module path is no longer the primary way to import its serializers.

fix

Change your import paths from `rest_polymorphic.serializers` to `polymorphic.contrib.drf.serializers`.

AttributeError: 'Manager' isn't accessible via WorkflowNotification instances

This error occurs when you attempt to access a Django model manager (like `objects`) from a model instance rather than from the model class itself, a common anti-pattern that can manifest with polymorphic models when trying to perform queryset operations from an instance method.

fix

Access the manager via the model class (e.g., `Notification.objects.filter(...)`) instead of a model instance (`self.objects.filter(...)`).

django.db.utils.IntegrityError: Problem installing fixtures: The row in table 'my_app_artproject' with primary key '1' has an invalid foreign key: my_app_artproject.project_ptr_id contains a value '1' that does not have a corresponding value in my_app_project.id.

This `IntegrityError` typically arises when using Django's `dumpdata` and `loaddata` management commands with `django-polymorphic` models, as the default dumpdata often fails to correctly serialize the `ContentType` and parent model `_ptr` (pointer) foreign key relationships, leading to missing references during loading or incorrect cascade deletions.

fix

When dumping data, use the `--natural-foreign` flag with `manage.py dumpdata` (e.g., `python manage.py dumpdata --natural-foreign --indent=4 my_app > data.json`) to ensure foreign key relationships, including polymorphic ones, are serialized by value rather than primary key.

Upgrade

Version history

0.1.10latest on PyPI · released Jul 17, 2022

Audit

Dependencies

django-polymorphicrequiredRequired for defining polymorphic models that django-rest-polymorphic serializes.

djangorestframeworkrequiredIt's an extension for Django REST Framework.

Agent activity

11 hits · last 30 days

node

Resources

githubhttps://github.com/denisorehovsky/django-rest-polymorphic ↗

packagehttps://pypi.org/project/django-rest-polymorphic/ ↗