I have the following serializer:
class AMXModXAdminsSerializer(mixins.GetCSConfigMixin, serializers.ModelSerializer):
admin = serializers.CharField(label='Admin', max_length=35, required=True, write_only=True)
password = serializers.CharField(label='Password', max_length=35, required=False, write_only=True)
access_flags = serializers.MultipleChoiceField(choices=ACCESS_FLAGS_OPTIONS, required=True, write_only=True)
account_flags = serializers.MultipleChoiceField(choices=ACCOUNT_FLAGS_OPTIONS, required=True, write_only=True)
class Meta:
model = CS16Server
fields = ('name', 'amxadmins', 'admin', 'password', 'access_flags', 'account_flags')
read_only_fields = ('name', 'amxadmins',)
When I try to access the url it complains:
Got AttributeError when attempting to get a value for field `admin` on serializer `AMXModXAdminsSerializer`.
The serializer field might be named incorrectly and not match any attribute or key on the `CS16Server` instance.
Original exception text was: 'CS16Server' object has no attribute 'admin'.
If I add write_only to each field, the error will go away.
The thing is that I have a similar serializer, for the same model, with fields which do not belong to the model and it works perfectly without adding "write_only=True" to each field.
Any idea why one would work and another one no ?
What do u mean "when i access" ? post get put patch ?
Error says:
'CS16Server' object has no attribute 'admin'.
Does it ? if not , where do u intend to write it to ?
If model does not have admin field (as mentioned in error ) you need something like this:
class AMXModXAdminsSerializer(mixins.GetCSConfigMixin, serializers.ModelSerializer):
admin= serializers.SerializerMethodField()
fields ...
...
def get_admin(self, obj):
do somthing with self (contains the request) or the obj you're working on
return theOUTcome
If you set required=False it will not complain anymore because it will not try to get those fields values from db.
Related
I'm trying to show the primary key in the examples section of Swagger, I'm using drf-spectacular and my code looks like:
Serializers.py
class SerializerExample(serializers.ModelSerializer):
class Meta:
model = Book
fields = ('id','name')
Views.py
class BooksBulkUpdate(APIView):
#extend_schema(
request=SerializerExample(many=True),
responses={200:''},
)
def put(self, request, format=None):
with transaction.atomic():
for data in request.data:
book = Book.objects.get(pk=data['id'])
serializer = SerializerExample(book, data=data, partial=True)
if serializer.is_valid():
serializer.save()
else:
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
return Response()
Only the name field is showing:
The only solution that I found was using an inline serializer which is not the ideal solution because if I update my book serializer I'd have to remember to update also this inline serializer. I wonder if there is a better way of doing this.
AFAIK swagger shows input request schema.
For example, you want to add new person and your model is
class Person(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
name = models.CharField(max_length=30)
So you allowed to set only name parameter
Even if you post
{
"id": "someUUID",
"name": "NAME",
}
id will be ignored and Django create it automatically by own logic (because it is read only)
But you can set id field writeable:
class SerializerExample(serializers.ModelSerializer):
id = serializers.UUIDField(write_only=True)
name = serializers.CharField(write_only=True)
class Meta:
model = Person
fields = ('id','name')
write_only=True means that field will be active when you saving new data and receiving id from request json.
In opposite read_only=True will print id field at response (if you trying get data) but ignore it when you saving new data.
So you try to describe API for data adding, and of course that is not allow to set id field in request json.
Not sure if this theory applicable to your case, but hope that will be helpful.
I have a simple serializer with one required field:
class MySerializer(serializers.ModelSerializer):
class Meta:
model = MyModel
fields = '__all__'
read_only_fields = ('field1', 'field2')
In my model there is an 'url' field which is required to create new object (method: POST). I would like to set required: False for PUT method. How can I achieve that? Thanks for any clues...
I assume you want to change/set one or multiple fields of an existing MyModel instance.
In such case, you need to pass a partial=True keyword argument to serializer. Then even if you PUT or PATCH without url field in data, your serializer.is_valid() would evaluate to True.
https://www.agiliq.com/blog/2019/04/drf-polls/#edit-a-poll-question should help if my assumption about your question is correct.
I found this answer helpful: Django Rest Framework set a field read_only after record is created .
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
if self.instance is not None:
self.fields.get('url').read_only = True
This code works fine.
We can use serializer as a field inside another serializer..
Wonder why there's a Field class and Serializer class in DRF?
class CommentSerializer(serializers.Serializer):
user = UserSerializer()
content = serializers.CharField(max_length=200)
created = serializers.DateTimeField()
example serializer is taken from the doc https://www.django-rest-framework.org/api-guide/serializers/
As you can see, UserSerializer is much like a Field .
I'm just curious why they have serializer and field class separately..
Serilaizer is infact a field in DRF. Serializers can be nested and that is why it can be used as a field in other serializers. And yes, if you check the source code, the BaseSerializer is a subclass of Field as the serializer is just a special case of a field.
In my opinion:
In django rest framwork, you can think Serializer like a mask. It cover your origin data and change it to anything you want. Like format your json data , or validate your input data have correct format or not.
In your example,
content = serializers.CharField(max_length=200)
created = serializers.DateTimeField()
Comment have 2 direct field type CharField and DateTimeField.
user = UserSerializer()
Comment have field type is UserSerializer. This is different Serializer, and django know your CommentSerializer will have relationship with UserSerializer. And anything define in UserSerializer will use in here, for format json output or validate. And with define this nested objects, your output json will have more data like
'user': {'email': 'foobar', 'username': 'doe'}
And if you want create Comment with one user, you must pass all validate define in UserSerializer.
Conclude: in this example
Field class use for direct field.
Serializer class for relationship with other class
i want to ordering on my fields like this:
class DealerBackOfficeViewSet(mixins.ListModelMixin,
mixins.RetrieveModelMixin,
mixins.CreateModelMixin,
mixins.UpdateModelMixin,
viewsets.GenericViewSet):
filter_backends = (filters.OrderingFilter,
)
ordering_fields = ('online',...)
this way of ordering work only on model's fields but online field defined in my serializer and while test in postman not work.
i want to done it like this :
class CustomOrdering(filters.OrderingFilter):
def filter_queryset(self, request, queryset, view):
params = request.query_params.get(self.ordering_param)
if params == 'online':
... my serializer codes
return super(CustomOrdering, self).filter_queryset(request, queryset, view)
this problem is other fields ordering not work!! is there a way to solve it any way?
if related docs help me please give me the link .
thanks for your site
after struggle in this challenge i undrestand that exist a way to some how indicate this fields as model field and not need to CustomOrdering and any extra codes!
in my get_queryset function i change the code:
queryset = Dealer.objects.all()
to:
queryset = Dealer.objects.all().annotate(bids_count=Count('bid'), device_count=Count('device'))
note that this two fields in my serializer not in my model.
in my serilizer change this two field from SerializerMethodField to IntegerField and clean the defs.
then in my api file add this:
filter_backends = (filters.OrderingFilter,)
ordering_fields = ('bids_count', 'device_count')
this my last serializer:
class DealerListSerializer(serializers.ModelSerializer):
device_count = serializers.IntegerField()
bids_count = serializers.IntegerField()
class Meta:
model = Dealer
fields = ('id', 'last_name', 'first_name', 'username', 'person_trust', 'is_active',
'work_type', 'address', 'mobile', 'device_count', 'online', 'bids_count')
by this way my code is very clear and my CustomOrdering and all elif statements also clean!
It doesn't work because the fields defined in your serializer aren't part of the model. The ordering attribute only works for model fields. You'd probably have to introduce a work around like creating a dynamic field using annotations and then order using that field but this depends on whether or not your online field logic can be annotated.
Let's say I have this simple model :
class BlogPost(models.Model):
author = models.ForeignKey(MyUser)
body = models.TextField()
title = models.CharField(max_length=64)
urlid = models.CharField(max_length=32)
private_data = models.CharField(max_length=64)
private_data contains data that I do not want to expose to the API (!). I'm using a ModelSerializer :
class BlogPostSerializer(serializers.ModelSerializer):
class Meta:
model = BlogPost
def __init__(self, *args, **kwargs):
# Don't pass the 'request' arg up to the superclass
request = kwargs.pop('request', None)
# Instatiate the superclass normally
super(ModelSerializer, self).__init__(*args, **kwargs)
self.request = request
def absolute_url(self, blogpost):
return blogpost.get_absolute_url(self.request)
The absolute_url method needs the request to determine the domain name (dev or prod for example) and if it was made in http or https.
I want to specify which fields in the model are going to get returned by the serializer (not expose private_data for example). Simple enough:
class BlogPostSerializer(serializers.ModelSerializer):
class Meta:
model = BlogPost
fields = ('author', 'body', 'title', 'urlid',)
# The same jazz after that
All right, it works. Now I also want to return absoluteUrl:
class BlogPostSerializer(serializers.ModelSerializer):
absoluteUrl = serializers.SerializerMethodField('absolute_url')
class Meta:
model = BlogPost
fields = ('author', 'body', 'title', 'urlid',)
# The same jazz after that
Well, without surprises, this returns only the fields I specified, without the absoluteUrl. How can I return only certain fields of the model AND the absoluteUrl, calculated from the serializer?
If I don't specify fields I do get the absoluteUrl, but with all the model's fields (including private_data). If I add 'absoluteUrl' to fields I get an error because blogpost.absoluteUrl doesn't exist (no surprises there). I don't think I could use this method http://django-rest-framework.org/api-guide/serializers.html#specifying-fields-explicitly because I need the request to obtain the absoluteUrl (or can I specify arguments to the model's method ?)
If I don't specify fields I do get the absoluteUrl, but with all the model's fields (including private_data). If I add 'absoluteUrl' to fields I get an error because blogpost.absoluteUrl doesn't exist (no surprises there).
You should just be adding 'absoluteUrl' to the fields tuple, and it should work just fine - so what error are you seeing?
The absolute_url method needs the request to determine the domain name (dev or prod for example) and if it was made in http or https.
Note that you can also pass through context to the serializer without modfiying the __init__, just pass a context={'request': request} when instantiating the serializer. The default set of generic views do this for you, so you can access self.context['request'] in any of the serializer methods. (Note that this is how hyperlinked relationships are able to return fully qualified URLs)