Get current user in Model Serializer

Question

Is it possible to get the current user in a model serializer? I'd like to do so without having to branch away from generics, as it's an otherwise simple task that must be done.

My model:

class Activity(models.Model):     number = models.PositiveIntegerField(         blank=True, null=True, help_text="Activity number. For record keeping only.")     instructions = models.TextField()     difficulty = models.ForeignKey(Difficulty)     categories = models.ManyToManyField(Category)     boosters = models.ManyToManyField(Booster)      class Meta():         verbose_name_plural = "Activities" 

My serializer:

class ActivitySerializer(serializers.ModelSerializer):      class Meta:         model = Activity 

And my view:

class ActivityDetail(generics.RetrieveUpdateDestroyAPIView):      queryset = Activity.objects.all()     serializer_class = ActivityDetailSerializer 

How can I get the model returned, with an additional field user such that my response looks like this:

{     "id": 1,      "difficulty": 1,      "categories": [         1     ],      "boosters": [         1     ],     "current_user": 1 //Current authenticated user here } 

Answer 1

I found the answer looking through the DRF source code.

class ActivitySerializer(serializers.ModelSerializer):          # Create a custom method field     current_user = serializers.SerializerMethodField('_user')      # Use this method for the custom field     def _user(self, obj):         request = self.context.get('request', None)         if request:             return request.user      class Meta:         model = Activity         # Add our custom method to the fields of the serializer         fields = ('id','current_user') 

The key is the fact that methods defined inside a ModelSerializer have access to their own context, which always includes the request (which contains a user when one is authenticated). Since my permissions are for only authenticated users, there should always be something here.

This can also be done in other built-in djangorestframework serializers.

As Braden Holt pointed out, if your user is still empty (ie _user is returning None), it may be because the serializer was not initialized with the request as part of the context. To fix this, simply add the request context when initializing the serializer:

serializer = ActivitySerializer(     data=request.data,     context={         'request': request     } ) 

Answer 2

A context is passed to the serializer in REST framework, which contains the request by default. So you can just use self.context['request'].user inside your serializer.