class OrderProductCreateSerializer(serializers.ModelSerializer):
class Meta:
model = OrderProduct
fields = ('product',)
class OrderProductCreateSerializer(serializers.ModelSerializer):
class Meta:
model = OrderProduct
fields = ('product',)
class OrderCreateSerializer(serializers.Serializer):
products = OrderProductCreateSerializer(many=True, required=True)
When field is named products I get None as result. When field is named as any other string (products1) I get valid results.
There is no special processing involved anywhere in code base related to products, just a simple many=True field.
Related
In my Django Rest Framework project, I have a ForeignKey relationship between two models:
class Book(models.Model):
...
category = models.ForeignKey(Category, on_delete=models.CASCADE, blank=True, null=True)
...
class Category(models.Model):
name = models.CharField(max_length=100, blank=False)
As you can see, a Book can belong to a Category but it does not have to. That means the 'category' field could be null.
So, in my views.py, any Book instance can be updated/patched if the user wants to assign a certain Book to a particular Category. That views.py update method looks like this:
class UpdateBooksCategory(generics.GenericAPIView):
'''
Class-based view to update the 'category' field of a Book instance.
'''
serializer_class = BookSerializer
permission_classes = [IsAuthenticated]
def patch(self, request,*args, **kwargs):
# get the Book instance first
book = Book.objects.get(pk=request.data.get('bookId'))
# if it is not assigned to a Category, then assign it
if book and not book.category:
book.category = Category.objects.get(name=request.data.get('categoryName'))
book.save()
serializer = self.get_serializer(book, context={"request": request})
return Response(serializer.data)
# otherwise, return a generic response
return Response({'response': "You have already put the selected Book in a Category."})
If you can see, first I get the Book instance that the user wants to update by using the Book's ID. If its Category field is not already filled, I get a Category instance using the given category name and assign it.
For the sake of completeness, here are my serializer classes:
class CategorySerializer(serializers.ModelSerializer):
class Meta:
model = Category
fields = ['id', 'name']
class BookSerializer(serializers.ModelSerializer):
class Meta:
model = Book
fields = ['id', /*some other fields*/,..., 'category']
So, finally my question: I wanted to know if this is the preferred way of updating a ForeingKey field like this? I mean looking at the UpdateBooksCategory class-based view, is this the right way of doing it? The code works ( I tested it with PostMan) but since I am new to DRF I wanted to know if such an updating process is correct.
You can change your BookSerializer:
class BookSerializer(serializers.ModelSerializer):
category_id = serializers.IntegerField(write_only=True)
category = CategorySerializer(read_only=True)
class Meta:
model = Book
fields = [
'id',
# some other fields,
'category',
'category_id',
]
category will be a nested data that is read only, then setting the category will be by including the category_id in your requests.
I want to use HyperLinkedModelSerializer in order to add a url field for my Book model. Here is the solution you'd typically find in the average tutorial:
# serializers.py
class BookSerializer(HyperLinkedModelSerializer):
class Meta:
model = Book
fields = ("title", "url",)
# views.py
class BookView(RetrieveAPIView):
serializer_class = BookSerializer
# urls.py
urlpatterns = [
path("<pk>/", BookDetailView.as_view(), name="book-detail"),
]
And that works all right. But now I need to change the URL conf in order to match the book id, not with <pk>, but with <fiction_id>. So I figured I'd just change it!
# urls.py
urlpatterns = [
path("<fiction_id>/", BookDetailView.as_view(), name="book-detail"),
]
Now comes the crash:
django.core.exceptions.ImproperlyConfigured: Could not resolve URL for hyperlinked relationship using view name "fiction-detail". You may have failed to include the related model in your API, or incorrectly configured the `lookup_field` attribute on this field.
I've tried fiddling with the lookup_field, lookup_url_kwargs in my view:
# views.py
class BookView(RetrieveAPIView):
serializer_class = BookSerializer
lookup_field = "pk"
lookup_url_kwargs = "fiction_id"
I've tried reminding the serializer to actually look for the (default) "pk":
# serializers.py
class BookSerializer(HyperLinkedModelSerializer):
class Meta:
model = Book
fields = ("title", "url",)
extra_kwargs = {
"url": {"lookup_field": "pk"},
}
I've tried combinations of these, to no avail. It looks like you can't use anything but <pk> if you want to take advantage of HyperLinkedModelSerializer's url field. The documentation doesn't seem to offer a way to change that behaviour:
By default hyperlinks are expected to correspond to a view name that matches the style '{model_name}-detail', and looks up the instance by a pk keyword argument.
How can I change this behaviour, or is it bound to become too messy?
You should check HyperlinkedModelSerializer implementation and see that it uses a serializer_related_field defaulting to HyperlinkedRelatedField
class HyperlinkedModelSerializer(ModelSerializer):
"""
A type of `ModelSerializer` that uses hyperlinked relationships instead
of primary key relationships. Specifically:
* A 'url' field is included instead of the 'id' field.
* Relationships to other instances are hyperlinks, instead of primary keys.
"""
serializer_related_field = HyperlinkedRelatedField
...
And then HyperlinkedRelatedField has a class attribute lookup_field defaulting to pk
class HyperlinkedRelatedField(RelatedField):
lookup_field = 'pk'
...
What you can do is to use a custom HyperlinkedRelatedField with your own lookup_field
from rest_framework.relations import HyperlinkedRelatedField
from rest_framework.serializers import HyperlinkedModelSerializer
class BookHyperlinkedRelatedField(HyperlinkedRelatedField):
lookup_field = 'fiction_id'
class BookSerializer(HyperLinkedModelSerializer):
serializer_related_field = BookHyperlinkedRelatedField
class Meta:
model = Book
fields = ("title", "url",)
In order to do this, you need to give the url field's new name for the lookup in the matched pattern by passing it through the extra_kwargs dictionary:
# serializers.py
class BookSerializer(HyperLinkedModelSerializer):
class Meta:
model = Book
fields = ("title", "url",)
extra_kwargs = {
"url": {"lookup_url_kwarg": "fiction_id"},
}
Also remember to modify the corresponding view:
# views.py
class BookView(RetrieveAPIView):
serializer_class = BookSerializer
lookup_url_kwarg = "fiction_id"
Do not write lookup_url_kwargs in plural.
You don't need to meddle with the lookup_field at any level as long as the lookup will be done on the model's primary key.
I'm now using DRF as a backend of my project.
i have product model like this
class product(models.Model):
product_name = models.CharField(max_length=160)
i have category model like this
class category(models.Model):
category_name = models.CharField(max_length=60)
category_icon = models.ImageField(upload_to='category)
because 1 product can have multiple category and a lot of image I create
class product_category(models.Model):
product = models.ForeignKey(product, on_delete=models.CASCADE, related_name='product_collections')
category = models.ForeignKey(category, on_delete=models.CASCADE, related_name='category_collections')
and the last model
class product_image(models.Model):
product = models.ForeignKey(product, on_delete=models.CASCADE,related_name='image_collections')
product_img = models.ImageField(upload_to='product')
Now I have Serializer like this
class ProductCategorySerializer(serializers.ModelSerializer):
category_name = serializers.CharField(source='category.category_name')
class Meta:
model = product_category
fields = ('product_id','category_id','category_name')
class ProductImageSerializer(serializers.ModelSerializer):
class Meta:
model = product_images
fields = ('product_img',)
class ProductSerializer(serializers.ModelSerializer):
category_collections = CategoryProductSerializers(many=True)
image_collections = ProductImageSerializer(many=True)
class Meta:
model = product
fields = ('id','product_name','image_collections','category_collections')
From that serializer DRF will return
Error like this
Got AttributeError when attempting to get a value for field category_collections on serializer ProductSerializer.
The serializer field might be named incorrectly and not match any attribute or key on the product instance.
but if i remove that category_collections field like this
class ProductSerializer(serializers.ModelSerializer):
# category_collections = CategoryProductSerializers(many=True)
image_collections = ProductImageSerializer(many=True)
class Meta:
model = product
fields = ('id','product_name','image_collections')
Everything is going fine, whats wrong with that categories collection, is my eye not seeing the mistake ?
I have three classes.In OrdFactory i wana pass only id to "sku" field and sku is integer field.
class CoFactory(factory.django.DjangoModelFactory):
class Meta:
model = models.Co
name = factory.Sequence(lambda n: 'Co {}'.format(n))
class CrFactory(factory.django.DjangoModelFactory):
class Meta:
model = models.Cr
name = factory.Sequence(lambda n: 'Cr {}'.format(n))
class OrdFactory(factory.django.DjangoModelFactory):
class Meta:
model = models.Ord
sku = random.choice([factory.SubFactory(CrFactory), factory.SubFactory(CoFactory)])
quantity = 75.6
I am getting following error.
int() argument must be a string, a bytes-like object or a number, not 'Co'.
I have tried using id also:-
sku = random.choice([factory.SubFactory(CrFactory).id, factory.SubFactory(CoFactory).id])
but this also throwing error.
I have fixed using trait.Overload is also a alternative solution.
https://factoryboy.readthedocs.io/en/latest/reference.html#factory.Trait
I'm trying to serialize a model containing a property field that I also want to serialize.
models.py:
class MyModel(models.Model):
name = models.CharField(max_length=100)
slug = models.AutoSlugField(populate_from='name')
#property
def ext_link(self):
return "/".join([settings.EXT_BASE_URL, self.slug])
serializers.py:
class MyModelSerializer(serializers.ModelSerializer):
class Meta:
model = MyModel
fields = ('name', 'ext_link')
When trying to get to the related URL, I'm getting a serializer exception (KeyError) on the ext_link property.
How can I serialize the ext_link property?
Because it's not a model field, it needs to be added explicitly to the serializer class
class MyModelSerializer(serializers.ModelSerializer):
ext_link = serializers.Field()
class Meta:
model = MyModel
fields = ('name', 'ext_link')
as #Robert Townley's comment, this work with version 3.8.2:
class MyModelSerializer(serializers.ModelSerializer):
ext_link = serializers.ReadOnlyField()
class Meta:
model = MyModel
fields = "__all__"
The accepted answer doesn't seem to work for me, nor does the ReadOnlyField.
However, I have had success when I use a field that corresponds to the return type of my property function.
So for the example, I would do this:
class MyModelSerializer(serializers.ModelSerializer):
ext_link = serializers.CharField()
class Meta:
model = MyModel
fields = ('name', 'ext_link')
I've been able to do this with ListField, DictField, and IntegerField as well.
Another thing you might want to do is add a property that its contents are not a string. Let's say you have a model called Person and another one called Food that look like this (we assume that each food is the favorite of only one person, making it a OneToMany connection):
class Person(models.Model):
name = models.CharField(max_length=255)
#property
def favorite_foods(self):
return Food.objects.filter(person=self.pk)
class Food(models.Model):
name = models.CharField(max_length=255)
persons_favorite = models.ForeignKey(Person, on_delete=models.CASCADE)
If you want to add favorite_foods in Person's serializer all you have to do is:
class PersonSerializer(serializers.ModelSerializer):
favorite_foods = FoodSerializer(read_only=True, many=True)
class Meta:
model = Person
fields = ('name', 'favorite_foods')