How to override model field validation in django rest framework ModelSerializer - django

I have the following model:
class UserProfile(models.Model):
mobileNumber = models.BigIntegerField(primary_key=True)
authKey = models.CharField(max_length=300,null=False,blank=False)
creationDateTime = models.DateTimeField(auto_now_add=True)
lastUpdateDateTime = models.DateTimeField(auto_now=True)
Serializer:
class UserProfileSerializer(serializers.ModelSerializer):
class Meta:
model = UserProfile
fields = ('mobileNumber','authKey')
If userprofile model already has a mobilenumber XX44 and if I try to serialize using UserProfileSerializer with json {'mobileNumber': XX44, 'authKey': u'ggsdsagldaslhdkjashdjkashdjkahsdkjah'} I'm getting the following error:
{'mobileNumber': [u'User profile with this MobileNumber already exists.']}
because model validations are being run for the serializer field.
How can I stop execution of model field validation for mobileNumber. I have tried validate and validate_mobileNumber methods in serializer but they still are executing the model validations.

remove unique constraint on mobile number of table,so django serializer will validate according to that .
or
alternatively,
serializer=UserProfileSerializer(data=request.DATA,partial=True)

I understand you won't save the serializer data. So, you can set mobileNumber as a read_only field on UserProfileSerializer.
Check serializer fields documentation for more info: http://www.django-rest-framework.org/api-guide/fields/#core-arguments

By overriding the model field within the serializer, and specifying required=False, allow_blank=True, allow_null=True:
class SomeModel(models.Model):
some_model_field_which_is_required = models.ForeignKey(...)
some_other_required_field = models.CharField(...)
class SomeModelSerializer(serializers.ModelSerializer):
some_model_field_which_is_required = SomeNestedSerializer(
many=True, required=False, allow_blank=True
)
some_other_required_field = serializers.CharField(required=False, allow_blank=True)
def validate(self, *args, **kwargs):
print('should get here')
def validate_some_other_required_field(self, *args, **kwargs):
print('should also get here')
class Meta:
model = SomeModel

Related

display only some fields in get api response django serializer

I have an example model which has a fk relation with user model and Blog model. Now I have a get api which only requires certain fields of user to be displayed.
My model:
class Example(models.Model):
user = models.ForeignKey(
settings.AUTH_USER_MODEL,
on_delete=models.CASCADE,
null=True,
related_name="user_examples",
)
blog = models.ForeignKey(
Blog,
on_delete=models.CASCADE,
null=True,
related_name="blog_examples",
)
/................./
Now my view:
class ExampleView(viewsets.ModelViewSet):
queryset = Example.objects.all()
serializer_class = ExampleSerializer
def list(self, request, *args, **kwargs):
id = self.kwargs.get('pk')
queryset = Example.objects.filter(blog=id)
serializer = self.serializer_class(queryset,many=True)
return Response(serializer.data,status=200)
My serializer:
class ExampleSerializer(serializers.ModelSerializer):
class Meta:
model = Example
fields = ['user','blog','status']
depth = 1
Now when I call with this get api, I get all example objects that is required but all the unnecessary fields of user like password, group etc . What I want is only user's email and full name. Same goes with blog, I only want certain fields not all of them. Now how to achieve this in a best way??
You will have to specify the required fields in nested serializers. e.g.
class BlogSerializer(serializers.ModelSerializer):
class Meta:
model = Blog
fields = ['title', 'author']
class ExampleSerializer(serializers.ModelSerializer):
blog = BlogSerializer()
class Meta:
model = Example
fields = ['user','blog','status']
are you setting depth in serializer's init method or anywhere else? beacause ideally it should only display id's and not anything else. if yes then set depth to zero and use serializer's method field to return data that you need on frontend. I can provide you with example code samples

How to lookup by field inherited from OneToOneField of another model

I am attempting to lookup UserProfile model using a field inherited from the User model. How can I access the username field from the User model in UserProfile view?
I am using Django REST framework 3.9. And from my understanding, using the #property annotation in the Model definition allows you to serialize on that field. And I am using that serialized field as lookup_field in the view.
This is the UserProfile model.
class UserProfile(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
bio = models.TextField(max_length=500, null=True, blank=True)
birth_date = models.DateField(null=True, blank=True)
#property
def username(self):
return self.user.username
This is the serializer.
class UserProfileSerializer(serializers.ModelSerializer):
class Meta:
model = UserProfile
fields = [
'user',
'username',
'bio',
'birth_date'
]
This is the view.
class UserProfileAPIView(generics.RetrieveUpdateAPIView):
# permission_classes = [permissions.IsAuthenticated]
serializer_class = UserProfileSerializer
lookup_field = 'username'
def get_queryset(self):
return UserProfile.objects.all()
def get_serializer_context(self, *args, **kwargs):
return {'request': self.request}
This is the API URL.
path('<str:username>/profile/', UserProfileAPIView.as_view(), name='profile'),
I expected the API to return username, bio, birth_date, but I received this error:
Cannot resolve keyword 'username' into field. Choices are: bio, birth_date, id, user, user_id
#property is just a Python calculated field here, which will be available only after the object is available. But to get the objects this cannot be used.
lookup_field requires a DB relation. As I said before, we cannot use the username property for this. It should be lookup_field = 'user__username'.
Add source to the Hyperlink identity field.
URL = HyperlinkIdentityField(
view_name='your_view_name',
source=User,
lookup_field='username'
)

Invalid data. Expected a dictionary, but got str error with serializer field in Django Rest Framework

I'm using Django 2.x and Django REST Framework.
I have two models like
class Contact(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
user = models.ForeignKey(User, on_delete=models.PROTECT)
first_name = models.CharField(max_length=100)
last_name = models.CharField(max_length=100, blank=True, null=True)
modified = models.DateTimeField(auto_now=True)
created = models.DateTimeField(auto_now_add=True)
class AmountGiven(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
contact = models.ForeignKey(Contact, on_delete=models.PROTECT)
amount = models.FloatField(help_text='Amount given to the contact')
given_date = models.DateField(default=timezone.now)
created = models.DateTimeField(auto_now=True)
the serializer.py the file has serializers defined as
class ContactSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Contact
fields = ('id', 'first_name', 'last_name', 'created', 'modified')
class AmountGivenSerializer(serializers.ModelSerializer):
contact = ContactSerializer()
class Meta:
model = AmountGiven
depth = 1
fields = (
'id', 'contact', 'amount', 'given_date', 'created'
)
views.py
class AmountGivenViewSet(viewsets.ModelViewSet):
serializer_class = AmountGivenSerializer
def perform_create(self, serializer):
save_data = {}
contact_pk = self.request.data.get('contact', None)
if not contact_pk:
raise ValidationError({'contact': ['Contact is required']})
contact = Contact.objects.filter(
user=self.request.user,
pk=contact_pk
).first()
if not contact:
raise ValidationError({'contact': ['Contact does not exists']})
save_data['contact'] = contact
serializer.save(**save_data)
But when I add a new record to AmountGiven model and passing contact id in contact field
it is giving error as
{"contact":{"non_field_errors":["Invalid data. Expected a dictionary, but got str."]}}
When I remove contact = ContactSerializer() from AmountGivenSerializer, it works fine as expected but then in response as depth is set to 1, the contact data contains only model fields and not other property fields defined.
I'm not a big fan of this request parsing pattern. From what I understand, you want to be able to see all the contact's details when you retrieve an AmountGiven object and at the same time be able to create and update AmountGiven by just providing the contact id.
So you can change your AmountGiven serializer to have 2 fields for the contact model field. Like this:
class AmountGivenSerializer(serializers.ModelSerializer):
contact_detail = ContactSerializer(source='contact', read_only=True)
class Meta:
model = AmountGiven
depth = 1
fields = (
'id', 'contact', 'contact_detail', 'amount', 'given_date', 'created'
)
Note that the contact_detail field has a source attribute.
Now the default functionality for create and update should work out of the box (validation and everything).
And when you retrieve an AmountGiven object, you should get all the details for the contact in the contact_detail field.
Update
I missed that you need to check whether the Contact belongs to a user (however, I don't see a user field on your Contact model, maybe you missed posting it). You can simplify that check:
class AmountGivenViewSet(viewsets.ModelViewSet):
serializer_class = AmountGivenSerializer
def perform_create(self, serializer):
contact = serializer.validated_data.get('contact')
if contact.user != self.request.user:
raise ValidationError({'contact': ['Not a valid contact']})
serializer.save()
Override the __init__() method of AmountGivenSerializer as
class AmountGivenSerializer(serializers.ModelSerializer):
def __init__(self, *args, **kwargs):
super(AmountGivenSerializer, self).__init__(*args, **kwargs)
if 'view' in self.context and self.context['view'].action != 'create':
self.fields.update({"contact": ContactSerializer()})
class Meta:
model = AmountGiven
depth = 1
fields = (
'id', 'contact', 'amount', 'given_date', 'created'
)
Description
The issue was the DRF expects a dict like object from contact field since you are defined a nested serializer. So, I removed the nested relationship dynamically with the help of overriding the __init__() method
For those who got here but have relatively simple serializers, this error can also occur when the request data is malformed, in my case JSON encoded twice.
The serializer will decode the JSON, but as it is encoded twice request.data will still be a string. The error therefore makes sense as a "dictionnary" was expected, but we still have a "string".
You can check the output of the following to confirm whether this is the issue you are experiencing:
print(type(request.data)) # Should be <class 'dict'>

Related Object serializer Django restframework

My question is somewhat related to this one with some differences. I have a model similar to this one:
class Project(models.Model):
project_id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False, unique=True)
created_by_id = models.ForeignKey('auth.User', related_name='project', on_delete=models.SET_NULL, blank=True, null=True)
created_by = models.CharField(max_length=255, default="unknown")
created = models.DateTimeField(auto_now_add=True)
With the following serializer:
class ProjectSerializer(serializers.ModelSerializer):
created_by = serializers.ReadOnlyField(source='created_by_id.username')
class Meta:
model = Project
fields = ('project_id', 'created_by', 'created')
And corresponding view:
class projectsView(mixins.ListModelMixin,
mixins.CreateModelMixin,
generics.GenericAPIView):
queryset = Project.objects.all()
serializer_class = ProjectSerializer
def get(self, request, *args, **kwargs):
return self.list(request, *args, **kwargs)
def post(self, request, *args, **kwargs):
return self.create(request, *args, **kwargs)
def perform_create(self, serializer):
serializer.save(created_by_id=self.request.user)
This code behaves like I want but forces information redundancy and does not leverage the underlying relationnal database. I tried to use the info from the linked question to achieve a "write user id on database but return username on "get"" in a flat json without success:
Removing the "created_by" field in the model. Replacing the serializer with:
class UserSerializer(serializers.ModelSerializer):
class Meta:
model = User
class ProjectSerializer(serializers.ModelSerializer):
created_by = UserSerializer(read_only=True)
created_by_id = serializers.PrimaryKeyRelatedField(
queryset=User.objects.all(), source='created_by', write_only=True)
class Meta:
model = Project
fields = ('project_id', 'created_by', 'created_by_id', 'created')
Which would NOT 100% give me what I want, i.e. replace the user id with the username in a flat json but return something like: {'project_id': <uuid>, 'created_by': <user json object>, 'created': <data>}. But still I get a {'created_by_id': ['This field is required.']} 400 error.
Question: How can I write a user id to a database object from the request.user information to refer to an actual user id but return a simple username in the GET request on the projectsView endpoint without explicitly storing the username in the Model? Or more generally speaking, how can I serialize database objects (Django models) into customer json response by using default serialization DRF features and default DRF views mixins?
Alternate formulation of the question: How can I store an ID reference to another DB record in my model (that can be accessed without it being supplied by the payload) but deserialize a derived information from that object reference at the serializer level such as one specific field of the referenced object?
I would recommend you to use Two different serializers for Get and POST operations. Change your serializers.py as
class ProjectGetSerializer(serializers.ModelSerializer):
created_by_id = serializers.StringRelatedField()
class Meta:
model = Project
fields = '__all__'
class ProjectCreateSerializer(serializers.ModelSerializer):
created_by_id = serializers.PrimaryKeyRelatedField(queryset=User.objects.all(), default=serializers.CurrentUserDefault())
def create(self, validated_data):
return Project.objects.create(**validated_data, created_by=validated_data['created_by_id'].username)
class Meta:
model = Project
fields = '__all__'
Also, I reccomend ModelViewSet for API class if you are looking for CRUD operations. Hence the view will be like this,
class projectsView(viewsets.ModelViewSet):
queryset = Project.objects.all()
def get_serializer_class(self):
if self.action == 'create':
return ProjectCreateSerializer
return ProjectGetSerializer
So, the payload to create Project is,
{
}
One thing you should remember, while you trying to create Project user must logged-in
UPDATE - 1
serializer.py
class ProjectCreateSerializer(serializers.ModelSerializer):
created_by_id = serializers.StringRelatedField()
class Meta:
model = Project
fields = '__all__'
def create(self, validated_data):
return Project.objects.create(**validated_data, created_by_id=self.context['request'].user)
views.py
class projectsView(viewsets.ModelViewSet):
queryset = Project.objects.all()
serializer_class = ProjectCreateSerializer
The error is in the write_only field options. The required parameter default value is set to True while the intent is to not make it required if we take a look at the model. Here in the view, I use the perform_create as post processing to save on the Model DB representation. Since required default value is True at the creation level, the first .save() to the DB fails. Since this is purely internal logic, the required is not necessary. So simply adding the required=False option on the PrimaryKeyRelatedField does the job:
class UserSerializer(serializers.ModelSerializer):
class Meta:
model = User
class ProjectSerializer(serializers.ModelSerializer):
created_by = UserSerializer(read_only=True)
created_by_id = serializers.PrimaryKeyRelatedField(
queryset=User.objects.all(), source='created_by', write_only=True, required=False)
class Meta:
model = Project
fields = ('project_id', 'created_by', 'created_by_id', 'created')
Enforcing the required=True at the Model level as well would require to override the .save function of the serializer if I insist on playing with the logic purely at the serializer level for deserialization. There might be a way to get the user ref within the serializer as well to keep the views implementation even more 'default'... This can be done by using the default value from Jerin:
class ProjectSerializer(serializers.ModelSerializer):
created_by = UserSerializer(read_only=True)
created_by_id = serializers.PrimaryKeyRelatedField(
queryset=User.objects.all(), source='created_by',
write_only=True,
required=False,
default=serializers.CurrentUserDefault())
class Meta:
model = Project
fields = ('project_id', 'created_by', 'created_by_id', 'created')
Now to flaten the json with username only, you need to use a slug field instead of the UserSerializer:
class ProjectSerializer(serializers.ModelSerializer):
created_by = serializers.SlugRelatedField(
queryset=User.objects.all(), slug_field="username")
created_by_id = serializers.PrimaryKeyRelatedField(
queryset=User.objects.all(), source='created_by', write_only=True, required=False)
class Meta:
model = Project
fields = ('project_id', 'created_by', 'created_by_id', 'created')
And then only the username field value of the User Model will show at the create_by json tag on the get payload.
UPDATE - 1
After some more tweaking here is the final version I came up with:
class ProjectSerializer(serializers.ModelSerializer):
created_by_id = serializers.PrimaryKeyRelatedField(
queryset=User.objects.all(), write_only=True, required=False, default=serializers.CurrentUserDefault())
created_by = serializers.SerializerMethodField('creator')
def creator(self, obj):
return obj.created_by_id.username
class Meta:
model = Project
fields = ('project_id', 'created_by_id', 'created_by', 'created')

Django Rest Framework - Set current user on model with unique constraint

I have a model that represents a device identifier and I'd like to create a unique constraint on the device identifier and the current user.
I was passing the user on the save method but I had to remove the constraint and now that I'm trying to write tests the poor code that I wrote becomes difficult to test. How can I write a serializer where I could set the currentuser as default and mantain the unique contrasint on the model.
This is my model
class DeviceIdentifier(models.Model):
owner = models.ForeignKey(HDSAuthUser, primary_key=True, on_delete=models.CASCADE)
id_device = models.UUIDField(primary_key=True)
insert_date = models.DateTimeField(auto_now_add=True)
and this is my serializer
class DeviceIdentifierSerializer(serializers.ModelSerializer):
"""
Device identifier serializer
"""
class Meta:
model = DeviceIdentifier
fields = ('id_device', 'owner')
and this is my view
class RegisterDevice(CreateAPIView):
"""
View for registering device for the logged user
"""
serializer_class = DeviceIdentifierSerializer
def post(self, request, *args, **kwargs):
obj = DeviceIdentifierSerializer(data=request.data)
obj.is_valid()
obj.save(owner=request.user)
return Response(True)
Add Unique constaint on models instead of Model Serializer, it will surely work.
class DeviceIdentifier(models.Model):
owner = models.ForeignKey(HDSAuthUser, on_delete=models.CASCADE)
id_device = models.UUIDField(primary_key=True)
insert_date = models.DateTimeField(auto_now_add=True)
class Meta:
unique_together = ('field1', 'field2',)
class DeviceIdentifierSerializer(serializers.ModelSerializer):
"""
Device identifier serializer
"""
class Meta:
model = DeviceIdentifier