How to group by date in queryset - json

Question

I need help with writing proper queryset in Django View. I have Post model with created_at (datetime field). I want to group it by date and return in a specific format.
models.py
class Post(TrackableDate):
title = models.CharField(max_length=255)
body = models.TextField()
created_at = models.DateTimeField(auto_now_add=True)
views.py
class PostViewSet(mixins.ListModelMixin,
viewsets.GenericViewSet):
queryset = Post.objects.all()
serializer_class = PostSerializer
serializers.py
class PostSerializer(serializers.ModelSerializer):
class Meta:
model = Post
fields = '__all__'
The usual response looks like:
[
{
"id": 1,
"text": "ok",
"created_at": "2012-12-12T12:30:00"
},
{
"id": 2,
"text": "ok",
"created_at": "2012-12-12T12:30:00"
},
{
"id": 3,
"text": "ok",
"created_at": "2012-12-13T12:30:00"
}
]
How to group and return like that?
{
"2012-12-12": [
{
"id": 1,
"text": "ok",
"created_at": "2012-12-12T12:30:00"
},
{
"id": 2,
"text": "ok",
"created_at": "2012-12-12T12:30:00"
}
],
"2012-12-13": [
{
"id": 3,
"text": "ok",
"created_at": "2012-12-13T12:30:00"
}
]
}
I tried to do
Post.objects.extra(select={'created_at': 'date(created_at)'}).values('created_at').annotate(available=Count('created_at'))
But it returns
<QuerySet [{'created_at': '2020-07-04', 'available': 7}, {'created_at': '2020-07-09', 'available': 2}]>

Answer 1

This is a helper function, you can accomplish your results like this, it may be a better solution. This is the one that I came up with
def group_by_date(mydata):
new_data = {}
for element in mydata:
v = element['created_at'].split('T')[0]
if v not in new_data.keys():
new_data[v] = []
new_data[v].append(element)
return new_data
You can override the get function of your API and rework the output
and override return Response(group_by_date(serializer.data), HTTP_200_OK)