I want to add an extra field (column) that is not in the model. So, I created a model form in which the new extra field is defined.
admin.py
class WorkingHourForm(forms.ModelForm):
extra_field = forms.CharField(max_length=100)
class Meta:
model = WorkingHour
fields = ['day', 'period', 'time_range', 'extra_field']
class WorkingHourInline(admin.TabularInline):
model = WorkingHour
form = WorkingHourForm
This should work because it's pretty much a copy of an example in the documentation.
However, this raises the error: Unable to lookup 'extra_field' on WorkingHour or WorkingHourInline
What did I do wrong?
class WorkingHourForm(forms.ModelForm):
extra_field = forms.CharField(label='extra_field', max_length=100)
class Meta:
model = WorkingHour
fields = ['day', 'period', 'time_range', 'extra_field']
class WorkingHourInline(admin.TabularInline):
model = WorkingHour
form = WorkingHourForm
Adding label='extra_field' solved this for me in a similar use of tabularinline.. I think the django admin example works as is but when used in conjunction with the admin.TabularInline, it does not. Hope that helps.
remove extra_field from fields = ['day', 'period', 'time_range', 'extra_field']. If you do like that django will tries to get value for the extra_field from model. so, it will raises an error.
After modification, Above code will look like
class WorkingHourForm(forms.ModelForm):
extra_field = forms.CharField(max_length=100)
class Meta:
model = WorkingHour
fields = ['day', 'period', 'time_range']
class WorkingHourInline(admin.TabularInline):
model = WorkingHour
form = WorkingHourForm
Try adding this in your form's Meta:
labels = {"extra_field": "blah"}
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 have the following models:
class Contact(models.Model):
class Meta:
managed = False
db_table = 'contact'
class ContactPhone(models.Model):
contact = models.ForeignKey(Contact, on_delete = models.CASCADE)
number = models.CharField(max_length = 45)
class Meta:
managed = False
db_table = 'contact_phone'
Also, I have the following serializers:
class ContactSerializer(serializers.ModelSerializer):
server_id = serializers.IntegerField(source='id', read_only=True)
class Meta:
model = Contact
fields = '__all__'
class ContactPhoneSerializer(serializers.ModelSerializer):
class Meta:
model = ContactPhone
fields = '__all__'
Now, I have a view that insert phone numbers for an existing contact.
The input is a json that looks like this:
data = {'contact_id': 12322,
'phones':[{'number': '89120000001'}]}
The view:
def insert_contact_phone(request):
for record in request.data['phones']:
data['contact_id'] = request.data['contact_id']
serializer = ContactPhoneSerializer(data = data)
if serializer.is_valid():
serializer.save()
I end up with the following error:
RelatedObjectDoesNotExist at /contacts/edit ContactPhone has no
contact.
What am I doing wrong?
If you specify __all__ for the fields in your ContactPhoneSerializer, it does not include contact_id.
So the contact_id taken from the json input is not serialized. It is basically ignored and when you try to save and create new ContactPhone - it fails, because it does not have contact's foreign key correctly set.
But simply adding contact_id to the serializer's fields won't solve your problem.
In your view, i recommend you to set the contact instead:
data['contact'] = request.data['contact_id']
and pass this to the ContactPhoneSerializer.
I think this is simple and probably a duplicate, but I cannot figure it out by looking at the documentation.
I have Django models as follows:
class Image(models.Model):
manor = models.ForeignKey(Manor, related_name='image_for_manor')
filename = models.CharField(max_length=30, null=True, blank=True)
class Manor(models.Model):
id = models.IntegerField(primary_key=True)
I want the user to be able to query the Manor and see the related Image. I'd like this JSON to be returned:
{
id: 572,
image: 'my/filepath.png'
}
This is my view:
#api_view(['GET'])
def manor(request, id):
mymanor = Manor.objects.get(id=id)
serializer = ManorSerializer(mymanor)
return JSONResponse(serializer.data)
And these are my serializers:
class ImageFilePathSerializer(serializers.ModelSerializer):
class Meta:
model = Image
fields = ('filename',)
class ManorSerializer(serializers.ModelSerializer):
image = ImageFilePathSerializer(source="image_for_manor")
class Meta:
model = Manor
fields = ('id', 'image')
But this doesn't work: I get an empty dictionary for image. (Even if it weren't empty, I realise it wouldn't be right, because I don't want the image property to be a dictionary: I want it to be a string.)
How can I change this to be correct? I cannot work it out.
As Kevin suggested , why dont you use ImageField which will give you url where your image is uploaded. although if you dont want to do that , here are some changes you have to do to get the result format you wanted.(Following solution assumes that only one image will be for one minor)
views.py ( why dont you ImageFilePathSerializer instead of another one as it also contains all the data you wanted)
#api_view(['GET'])
def manor(request, id):
mymanor = Image.objects.get(manor__id=id)
serializer = ImageFilePathSerializer(mymanor)
return Response(serializer.data)
serializers.py (add Id with filename in ImageFilePathSerializer)
class ImageFilePathSerializer(serializers.ModelSerializer):
class Meta:
model = Image
fields = ('id', 'filename',)
class ManorSerializer(serializers.ModelSerializer):
filename = serializers.ImageField(source="image_for_manor")
class Meta:
model = Manor
fields = ('id', 'filename')
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')