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https://github.com/LilyFoote/rest-framework-generic-relations
https://github.com/LilyFoote/rest-framework-generic-relations
Last synced: 17 days ago
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- Host: GitHub
- URL: https://github.com/LilyFoote/rest-framework-generic-relations
- Owner: LilyFoote
- Archived: true
- Created: 2014-04-12T12:52:30.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2023-01-15T17:37:09.000Z (almost 2 years ago)
- Last Synced: 2024-07-31T22:46:37.005Z (3 months ago)
- Language: Python
- Size: 112 KB
- Stars: 204
- Watchers: 6
- Forks: 30
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: Changelog.md
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README
# Rest Framework Generic Relations [](https://github.com/Ian-Foote/rest-framework-generic-relations/actions/workflows/tests.yml)
This library implements [Django REST Framework](http://www.django-rest-framework.org/) serializers to handle generic foreign keys.
# Requirements
Any currently-supported combination of Django REST Framework, Python, and Django.
# Installation
Install using `pip`...
```sh
pip install rest-framework-generic-relations
```
Add `'generic_relations'` to your `INSTALLED_APPS` setting.
```python
INSTALLED_APPS = (
...
'generic_relations',
)
```
# API Reference
## GenericRelatedField
This field serializes generic foreign keys. For a primer on generic foreign keys, first see: https://docs.djangoproject.com/en/dev/ref/contrib/contenttypes/
Let's assume a `TaggedItem` model which has a generic relationship with other arbitrary models:
```python
class TaggedItem(models.Model):
tag_name = models.SlugField()
content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
object_id = models.PositiveIntegerField()
tagged_object = GenericForeignKey('content_type', 'object_id')
```
And the following two models, which may have associated tags:
```python
class Bookmark(models.Model):
"""
A bookmark consists of a URL, and 0 or more descriptive tags.
"""
url = models.URLField()
tags = GenericRelation(TaggedItem)
class Note(models.Model):
"""
A note consists of some text, and 0 or more descriptive tags.
"""
text = models.CharField(max_length=1000)
tags = GenericRelation(TaggedItem)
```
Now we define serializers for each model that may get associated with tags.
```python
class BookmarkSerializer(serializers.ModelSerializer):
class Meta:
model = Bookmark
fields = ('url',)
class NoteSerializer(serializers.ModelSerializer):
class Meta:
model = Note
fields = ('text',)
```
The model serializer for the `TaggedItem` model could look like this:
```python
from generic_relations.relations import GenericRelatedField
class TagSerializer(serializers.ModelSerializer):
"""
A `TaggedItem` serializer with a `GenericRelatedField` mapping all possible
models to their respective serializers.
"""
tagged_object = GenericRelatedField({
Bookmark: BookmarkSerializer(),
Note: NoteSerializer()
})
class Meta:
model = TaggedItem
fields = ('tag_name', 'tagged_object')
```
The JSON representation of a `TaggedItem` object with `name='django'` and its generic foreign key pointing at a `Bookmark` object with `url='https://www.djangoproject.com/'` would look like this:
```json
{
"tagged_object": {
"url": "https://www.djangoproject.com/"
},
"tag_name": "django"
}
```
If you want to have your generic foreign key represented as hyperlink, simply use `HyperlinkedRelatedField` objects:
```python
class TagSerializer(serializers.ModelSerializer):
"""
A `Tag` serializer with a `GenericRelatedField` mapping all possible
models to properly set up `HyperlinkedRelatedField`s.
"""
tagged_object = GenericRelatedField({
Bookmark: serializers.HyperlinkedRelatedField(
queryset = Bookmark.objects.all(),
view_name='bookmark-detail',
),
Note: serializers.HyperlinkedRelatedField(
queryset = Note.objects.all(),
view_name='note-detail',
),
})
class Meta:
model = TaggedItem
fields = ('tag_name', 'tagged_object')
```
The JSON representation of the same `TaggedItem` example object could now look something like this:
```json
{
"tagged_object": "/bookmark/1/",
"tag_name": "django"
}
```
## Writing to generic foreign keys
The above `TagSerializer` is also writable. By default, a `GenericRelatedField` iterates over its nested serializers and returns the value of the first serializer that is actually able to perform `to_internal_value()` without any errors.
Note, that (at the moment) only `HyperlinkedRelatedField` is able to serialize model objects out of the box.
The following operations would create a `TaggedItem` object with it's `tagged_object` property pointing at the `Bookmark` object found at the given detail end point.
```python
tag_serializer = TagSerializer(data={
'tag_name': 'python',
'tagged_object': '/bookmark/1/'
})
tag_serializer.is_valid()
tag_serializer.save()
```
If you feel that this default behavior doesn't suit your needs, you can subclass `GenericRelatedField` and override its `get_serializer_for_instance` or `get_deserializer_for_data` respectively to implement your own way of decision-making.
## GenericModelSerializer
Sometimes you may want to serialize a single list of different top-level things. For instance, suppose I have an API view that returns what items are on my bookshelf. Let's define some models:
```python
from django.core.validators import MaxValueValidator
class Book(models.Model):
title = models.CharField(max_length=255)
author = models.CharField(max_length=255)
class Bluray(models.Model):
title = models.CharField(max_length=255)
rating = models.PositiveSmallIntegerField(
validators=[MaxValueValidator(5)],
)
```
Then we could have a serializer for each type of object:
```python
class BookSerializer(serializers.ModelSerializer):
class Meta:
model = Book
fields = ('title', 'author')
class BluraySerializer(serializers.ModelSerializer):
class Meta:
model = Bluray
fields = ('title', 'rating')
```
Now we can create a generic list serializer, which delegates to the above serializers based on the type of model it's serializing:
```python
bookshelf_item_serializer = GenericModelSerializer(
{
Book: BookSerializer(),
Bluray: BluraySerializer(),
},
many=True,
)
```
Then we can serialize a mixed list of items:
```python
>>> bookshelf_item_serializer.to_representation([
Book.objects.get(title='War and Peace'),
Bluray.objects.get(title='Die Hard'),
Bluray.objects.get(title='Shawshank Redemption'),
Book.objects.get(title='To Kill a Mockingbird'),
])
[
{'title': 'War and Peace', 'author': 'Leo Tolstoy'},
{'title': 'Die Hard', 'rating': 5},
{'title': 'Shawshank Redemption', 'rating': 5},
{'title': 'To Kill a Mockingbird', 'author': 'Harper Lee'}
]
```
## A few things you should note:
* Although `GenericForeignKey` fields can be set to any model object, the `GenericRelatedField` only handles models explicitly defined in its configuration dictionary.
* Reverse generic keys, expressed using the `GenericRelation` field, can be serialized using the regular relational field types, since the type of the target in the relationship is always known.
* The order in which you register serializers matters as far as write operations are concerned.
* Unless you provide a custom `get_deserializer_for_data()` method, only `HyperlinkedRelatedField` provides write access to generic model relations.