id field in django rest framework serializer

Question

I'm using django rest framework and just creating a simple serializer like this:

class PackageSerializer(serializers.HyperlinkedModelSerializer):      class Meta:         model = Package         fields = ('id', 'url', 'title','location') 

However I get this error:

KeyError at /cerberus/packages/ 'id' 

How come I can't get the primary key 'id' as part of my serialized data? Thanks for helping!

Answer 1

HyperlinkedModelSerializer doesn't include the id by default. In 2.2 and earlier you'll need to add it explicitly as a field...

class PackageSerializer(serializers.HyperlinkedModelSerializer):     id = serializers.Field()      class Meta:         model = Package         fields = ('id', 'url', 'title','location') 

From 2.3 onwards, you can simply add 'id' to the fields option...

class PackageSerializer(serializers.HyperlinkedModelSerializer):     class Meta:         model = Package         fields = ('id', 'url', 'title','location') 

From 3.x (< 3.3) onwards, you must use ReadOnlyField() instead of Field() if you want to add it explicitly and not use the fields option...

class PackageSerializer(serializers.HyperlinkedModelSerializer):     id = serializers.ReadOnlyField()      class Meta:         model = Package 

Answer 2

According to the Django Rest Framework Documentation:

The default implicitly-generated id field is marked as read_only. This causes it to be removed on updates.

Thus, if you need the id field in an update method, you must not declare it as read-only but use a read-write field instead:

class PackageSerializer(serializers.ModelSerializer):     id = serializers.IntegerField()