I'm new to using the DRF so I apologize if this is a trivial question but I've had no luck finding an answer thus far.
I'm using DRF along with Angularjs to create a single page application. When I make posts to my API I get this error to create a new Task object: task_id: [This field is required.] task_id is my primary key on this object. How can I make it so that it gets incremented automatically like it would on a Django Model Form?
class TaskSerializer(serializers.ModelSerializer):
class Meta:
model = Task
fields = ('route', 'date', 'task_id', )
class AddTask(generics.CreateAPIView):
serializer_class = TaskSerializer
def get(self, request, format=None):
response = {}
response['form'] = TaskForm().as_p()
return Response(response)
Are you using task_id in your application page? If not, then remove it from the serializer and DRF will automatically take care of this for you.
Something like this:
class TaskSerializer(serializers.ModelSerializer):
class Meta:
model = Task
fields = ('route', 'date',)
Related
I wanna change all fields of a json object except 'pk' in DRF. I just need to keep one json data. When adding a new data ,this one should override existing data. Is there a way to do it with django ?
my models.py
class ClientUser2(models.Model):
phone_number = models.CharField(max_length=20,unique=True)
name = models.CharField(max_length=100,blank=True)
status = models.IntegerField(default=1)
class ClientNameSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = ClientUser2
fields = ('url','phone_number','name','status','pk')
my views.py
class ClientViewSet(viewsets.ModelViewSet):
"""
API endpoint that allows messages to be viewed or edited.
"""
queryset = ClientUser2.objects.all()
serializer_class = ClientNameSerializer
and it's my api root
api_root
If you want to be able to only retrieve and update models you can use RetrieveUpdateApiView
Reference : https://www.django-rest-framework.org/api-guide/generic-views/#retrieveupdateapiview
I'm using Django 2.1, DRF 3.7.7.
I've some models and their relative (model) serializers: these models are nested, and so are the serializers.
Let me give an example:
# models.py
class City(models.Model):
name = models.CharField(max_length=50)
class Person(models.Model):
surname = models.CharField(max_length=30)
birth_place = models.ForeignKey(City)
# serializers.py
class CitySerializer(serializers.ModelSerializer):
class Meta:
model = models.CitySerializer
fields = "__all__"
class PersonSerializer(serializers.ModelSerializer):
birth_place = CitySerializer()
class Meta:
model = models.Person
fields = "__all__"
If I submit an AJAX request with a json like:
{'surname': 'smith', 'birth_place': 42}
I get back a Bad Request response, containing: Invalid data. Expected a dictionary, but got int.
If I submit a nested json like:
{'surname': 'smith', 'birth_place': {'id': 42, 'name': 'Toronto'}}
the relation is not converted, the id field is ignored and the rest is parsed to:
OrderedDict([('birth_place', OrderedDict([('name', 'Toronto')]))])
The following is the post method I'm using on a class-based view:
def post(self, request):
print("Original data:", request.data)
serializer = self.serializer_class(data=request.data)
if serializer.is_valid():
self.data = serializer.validated_data
print("Parsed data:", self.data)
...
I only need to get data from the endpoints connected to the serializers, I don't need to write/save anything through the REST interface, since the POST processing of the form is done by Django.
TL;DR: How should I correctly submit a JSON request to a nested serializer, without having to write handmade conversions? Did I commit errors in setting up the serializers?
Edit: I've discovered that by adding id = serializers.IntegerField() to the serializer parent class (e.g. City), the serializer parser now processes the id. At least now I'm able to perform actions in the backend with django.
Generic writing for nested serializers is not available by default. And there is a reason for that:
Consider, you are creating a person with a birthplace, using a POST request. It is not clear if the submitted city is a new one or an existing one. Should it return an error if there isn't such a city? Or should it be created?
This is why, if you want to handle this kind of relationship in your serializer, you need to write your own create() and update() methods of your serializer.
Here is the relevant part of the DRF docs: http://www.django-rest-framework.org/api-guide/relations/#writable-nested-serializers
It's definitely not clearly put into the docs of django-rest. If you follow the process of serializers processing the data for creation then it becomes clear that django manages m2m by saving the parent instance first and then adding the m2m values, but somehow the m2m fields don't go through the validation if you mark them as read_only.
The solution to this is to overr run_validation method of the serializer. The serializer should look like this:
class ExampleSerializer(serializers.ModelSerializer):
queryset = SomeModel.objects.all()
tags = TagSerializer(many=True, read_only=True)
class Meta:
model = SomeModel
fields = ['pk', 'name', 'tags']
def run_validation(self, data):
validated_data = super(StudyResourceSerializer, self).run_validation(data)
validated_data['tags'] = data['tags']
return validated_data
The request body should look like this:
{
"tags": [51, 54],
"name": "inheritance is a mess"
}
I basically have the following model in my project:
class ShellMessage(TimeStampedModel):
# There is a hidden created and modified field in this model.
ACTION_TYPE = (
('1' , 'Action 1'),
('2' , 'Action 2')
)
type = models.CharField(max_length=2,choices=ACTION_TYPE,default='1')
action = models.CharField(max_length=100)
result = models.CharField(max_length=300, blank=True)
creator = models.ForeignKey(User)
I created a serializer:
class ShellMessageSerializer(serializers.ModelSerializer):
class Meta:
model = ShellMessage
fields = ('action', 'type', 'result', 'creator')
And a ModelViewSet:
class ShellListViewSet(viewsets.ModelViewSet):
serializer_class = ShellMessageSerializer
queryset = ShellMessage.objects.all()
My issue is the following:
When I create a new ShellMessage with a POST to my API, I don't want to provide the foreignKey of 'creator' but instead just the username of the guy and then process it in my ViewSet to find the user associated with this username and save it in my ShellMessage object.
How can I achieve this using Django rest Framework? I wanted to supercharge create() or pre_save() methods but I'm stuck as all my changes overwrite 'normal' framework behavior and cause unexpected errors.
Thank you.
I finally find my solution just after posting my question :)
So I did the following:
class ShellListViewSet(viewsets.ModelViewSet):
serializer_class = ShellMessageSerializer
queryset = ShellMessage.objects.all()
def pre_save(self, obj):
obj.creator = self.request.user
return super(ShellListViewSet, self).pre_save(obj)
This is working as expected. I hope I did well.
UPDATE: This topic seems to be a duplicate to Editing django-rest-framework serializer object before save
If you intend to intercept and perform some processing before the object gets saved in the model database, then what you're looking for is overriding the method "perform_create" (for POST) or "perform_update" (for PUT/PATCH) which is present within the viewsets.ModelViewSet class.
This reference http://www.cdrf.co/3.1/rest_framework.viewsets/ModelViewSet.html lists all available methods within viewsets.ModelViewSet where you can see that the "create" method calls "perform_create" which in turn performs the actual saving through the serializer object (the object that has access to the model):
def perform_create(self, serializer):
serializer.save()
We can override this functionality that is present in the base class (viewsets.ModelViewSet) through the derived class (the ShellListViewSet in this example) and modify the model attribute(s) that you want to be changed upon saving:
class ShellListViewSet(viewsets.ModelViewSet):
serializer_class = ShellMessageSerializer
queryset = ShellMessage.objects.all()
def findCreator(self):
# You can perform additional processing here to find proper creator
return self.request.user
def perform_create(self, serializer):
# Save with the new value for the target model fields
serializer.save(creator = self.findCreator())
You can also opt to modify the model fields separately and then save (probably not advisable but is possible):
serializer.validated_data['creator'] = self.findCreator()
serializer.save()
Later if the object is already created and you also want to apply the same logic during an update (PUT, PATCH), then within "perform_update" you can either do the same as above through the "serializer.validated_data['creator']" or you could also change it directly through the instance:
serializer.instance.creator = self.findCreator()
serializer.save()
But beware with such updating directly through the instance as from https://www.django-rest-framework.org/api-guide/serializers/ :
class MyModelSerializer(serializers.Serializer):
field_name = serializers.CharField(max_length=200)
def create(self, validated_data):
return MyModel(**validated_data)
def update(self, instance, validated_data):
instance.field_name = validated_data.get('field_name', instance.field_name)
return instance
This means that whatever you assign to the "instance.field_name" object could be overriden if there is a "field_name" data set within the "validated_data" (so in other terms, if the HTTP Body of the PUT/PATCH Request contains that particular "field_name" resulting to it being present in the "validated_data" and thus overriding whatever value you set to the "instance.field_name").
I want to create entries in two tables (Log and Post) using the DRF Browseable API POST form.
The example below is contrived, but it outlines what I am trying to do.
class Post(models.Model):
info = models.CharField()
class Log(TimeStampedModel):
ip = models.GenericIPAddressField(('IP Address'))
name = models.CharField()
data = models.ForeignKey(Post)
I want to use the browseable API to submit a form to create a Log entry. Here are the serializers:
class PostSerializer(serializers.ModelSerializer):
class Meta:
model = Post
fields = ('info',)
class LogSerializer(serializers.ModelSerializer):
data = serializers.Field()
class Meta:
model = Log
fields = ('ip', 'name', 'data')
The problem with the above is that serializer.Field is read only so does not show up on the POST form. If I change it to CharField it shows up, but then I get an error because an instance of a Post is expected not just a field of the Post object.
Here are my views:
class LogMixin(object):
queryset = Log.objects.all()
serializer_class = LogSerializer
class LogList(LogMixin, ListCreateAPIView):
pass
class LogDetail(LogMixin, RetrieveUpdateDestroyAPIView):
pass
What's the correct way of doing this?
From what I can tell you want to create a nested Log object. There are 2 ways of doing this:
Send 2 POST Requests, One to create the Post, and the other to create the Log contained the received HTTP 200 data from the API.
(Django and best way) Send the data all in one POST and parse it server side. Django Rest Framework takes care of this for you.
I have changed your code so that it should work.
Source
class LogSerializer(serializers.ModelSerializer):
class Meta:
model = Log
fields = ('ip', 'name')
class PostSerializer(serializers.ModelSerializer):
log = LogSerializer()
class Meta:
model = Post
fields = ('info', 'log')
views.py
import generics
class PostCreateAPIView(generics.CreateAPIView):
model = Post
serializer_class = PostSerializer
Then you can send a POST Request containing 'info', 'ip', and 'name'.
This is a hacky way and the best way to use the nested serializer as stated above. But just to show another way I am posting it here.
# Add New Item
#api_view(('POST',))
def add_new_item(request):
request.data['areaname_name'] = request.data['item_areaname']
request.data['buildingname_name'] = request.data['item_buildingname']
item_serializer = TblItemSerializer(data=request.data)
area_name_serializer = TblAreanameSerializer(data=request.data)
building_name_serializer = TblBuildingnameSerializer(data=request.data)
response = []
if item_serializer.is_valid() & area_name_serializer.is_valid() & building_name_serializer.is_valid():
# Save To Item Table
item_serializer.save()
# Save Unique Values Into Areaname and Buildingname Tables
area_name_serializer.save()
building_name_serializer.save()
return Response(item_serializer.data, status=status.HTTP_201_CREATED)
else:
response.append(item_serializer.errors)
response.append(area_name_serializer.errors)
response.append(building_name_serializer.errors)
return Response(response, status=status.HTTP_400_BAD_REQUEST)
In the error response you could also use (depending on how you want to handle on client side)
merge = {**item_serializer.errors, **area_name_serializer.errors, **building_name_serializer.errors}
return Response(merge, status=status.HTTP_400_BAD_REQUEST)
In my app I have the following models:
class Zone(models.Model):
name = models.SlugField()
class ZonePermission(models.Model):
zone = models.ForeignKey('Zone')
user = models.ForeignKey(User)
is_administrator = models.BooleanField()
is_active = models.BooleanField()
I am using Django REST framework to create a resource that returns zone details plus a nested resource showing the authenticated user's permissions for that zone. The output should be something like this:
{
"name": "test",
"current_user_zone_permission": {
"is_administrator": true,
"is_active": true
}
}
I've created serializers like so:
class ZonePermissionSerializer(serializers.ModelSerializer):
class Meta:
model = ZonePermission
fields = ('is_administrator', 'is_active')
class ZoneSerializer(serializers.HyperlinkedModelSerializer):
current_user_zone_permission = ZonePermissionSerializer(source='zonepermission_set')
class Meta:
model = Zone
fields = ('name', 'current_user_zone_permission')
The problem with this is that when I request a particular zone, the nested resource returns the ZonePermission records for all the users with permissions for that zone. Is there any way of applying a filter on request.user to the nested resource?
BTW I don't want to use a HyperlinkedIdentityField for this (to minimise http requests).
Solution
This is the solution I implemented based on the answer below. I added the following code to my serializer class:
current_user_zone_permission = serializers.SerializerMethodField('get_user_zone_permission')
def get_user_zone_permission(self, obj):
user = self.context['request'].user
zone_permission = ZonePermission.objects.get(zone=obj, user=user)
serializer = ZonePermissionSerializer(zone_permission)
return serializer.data
Thanks very much for the solution!
I'm faced with the same scenario. The best solution that I've found is to use a SerializerMethodField and have that method query and return the desired values. You can have access to request.user in that method through self.context['request'].user.
Still, this seems like a bit of a hack. I'm fairly new to DRF, so maybe someone with more experience can chime in.
You have to use filter instead of get, otherwise if multiple record return you will get Exception.
current_user_zone_permission = serializers.SerializerMethodField('get_user_zone_permission')
def get_user_zone_permission(self, obj):
user = self.context['request'].user
zone_permission = ZonePermission.objects.filter(zone=obj, user=user)
serializer = ZonePermissionSerializer(zone_permission,many=True)
return serializer.data
Now you can subclass the ListSerializer, using the method I described here: https://stackoverflow.com/a/28354281/3246023
You can subclass the ListSerializer and overwrite the to_representation method.
By default the to_representation method calls data.all() on the nested queryset. So you effectively need to make data = data.filter(**your_filters) before the method is called. Then you need to add your subclassed ListSerializer as the list_serializer_class on the meta of the nested serializer.
subclass ListSerializer, overwriting to_representation and then calling super
add subclassed ListSerializer as the meta list_serializer_class on the nested Serializer
If you're using the QuerySet / filter in multiple places, you could use a getter function on your model, and then even drop the 'source' kwarg for the Serializer / Field. DRF automatically calls functions/callables if it finds them when using it's get_attribute function.
class Zone(models.Model):
name = models.SlugField()
def current_user_zone_permission(self):
return ZonePermission.objects.get(zone=self, user=user)
I like this method because it keeps your API consistent under the hood with the api over HTTP.
class ZoneSerializer(serializers.HyperlinkedModelSerializer):
current_user_zone_permission = ZonePermissionSerializer()
class Meta:
model = Zone
fields = ('name', 'current_user_zone_permission')
Hopefully this helps some people!
Note: The names don't need to match, you can still use the source kwarg if you need/want to.
Edit: I just realised that the function on the model doesn't have access to the user or the request. So perhaps a custom model field / ListSerializer would be more suited to this task.
I would do it in one of two ways.
1) Either do it through prefetch in your view:
serializer = ZoneSerializer(Zone.objects.prefetch_related(
Prefetch('zone_permission_set',
queryset=ZonePermission.objects.filter(user=request.user),
to_attr='current_user_zone_permission'))
.get(id=pk))
2) Or do it though the .to_representation:
class ZoneSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Zone
fields = ('name',)
def to_representation(self, obj):
data = super(ZoneSerializer, self).to_representation(obj)
data['current_user_zone_permission'] = ZonePermissionSerializer(ZonePermission.objects.filter(zone=obj, user=self.context['request'].user)).data
return data