Return dict indexed by primary key - django

Question

I have a realy simple API Endpoint which return a list of MyModel.
views.py:
#api_view(['GET'])
def index(request):
myModel = MyModel.objects.all()
serializer = MyModelSerializer(myModel, many=True)
return Response(serializer.data)
serializers.py
class MyModelSerializer(serializers.ModelSerializer):
class Meta:
model = MyModel
fields = ['field1', 'field2']
Now I'd like to return a serialized dictionary of models indexed by the primary key (which is a CharField).
{
'pk1':{
'field1': 'fo',
'field2': 'bar',
},
'pk2':{
'field1': 'fobar',
'field2': 'foo',
}
}
[EDIT] As requested, here is the model:
from django.db import models
class MyModel(models.Model):
id = models.CharField(primary_key=True)
field1 = models.FloatField(null=True)
field2 = models.FloatField(null=True)

Answer 1

You can override to_representation method in your serializer
class MyModelSerializer(serializers.ModelSerializer):
class Meta:
model = MyModel
fields = ['field1', 'field2']
def to_representation(self, instance):
ret = super().to_representation(instance)
return {instance.pk: ret}

Answer 2

You'll need to create a custom ListSerializer that will return a dictionary.
from django.db import models
from rest_framework import serializers
class DictSerializer(serializers.ListSerializer):
def to_representation(self, data):
iterable = data.all() if isinstance(data, models.Manager) else data
return [
(item.id, self.child.to_representation(item)) for item in iterable
]
#property
def data(self):
ret = super(DictSerializer, self).data
return serializers.ReturnDict(ret, serializer=self)
Then you'll have to specify that your ModelSerializer should use this custom when many=True. You do this by setting the list_serializer_class in the Meta of your ModelSerializer.
class MyModelSerializer(serializers.ModelSerializer):
class Meta:
model = MyModel
fields = ['field1', 'field2']
list_serializer_class = DictSerializer

Answer 3

If you want to be efficient following his Gabriel Muj solution is better but will not provide what you want out of the box. His solution will provide output like:
[{
'pk1': {
'field1': 'fo',
'field2': 'bar',
}
},
{
'pk2': {
'field1': 'fobar',
'field2': 'foo',
}
}
]
First change the serializer according to His solution:
class MyModelSerializer(serializers.ModelSerializer):
class Meta:
model = MyModel
fields = ['field1', 'field2']
def to_representation(self, instance):
ret = super().to_representation(instance)
return {instance.pk: ret}
But to get what you asked you need to use ChainMap from collections. Now you need to change your views like this:
from collections import ChainMap
#api_view(['GET'])
def index(request):
myModel = MyModel.objects.all()
serializer = MyModelSerializer(myModel, many=True)
data_dict = dict(ChainMap(*serializer.data))
return Response(data_dict)
For this snippet you need to make sure its python 3.3+ . This will provide good performance. While optimizing my code I have found this solution is less heavy.

Answer 4

You can iterate over the query set. In your index view:
#api_view(['GET'])
def index(request)
data = dict()
for element in MyModel.objects.all():
dict[element.id] = {'field1': element.field1, 'field2': element.field2}
return Response(data)