Django Query to get count of all distinct values for column of mongodb ArrayField

Question

What is the best way to count all distinct values in mongodb ArrayField? Here is my model:

class tweet(models.Model):              
   topic = models.JSONField()

3 sample documents:

1. ["investment", "economy"]
2. ["investment"]
3. ["economy", "politics"]

Desire result:

[{"investment":2},{"economy":2},{"politics":1}]

Maybe something like this:

tweet.objects.annotate(t=Func(F('topic'), function='$unwind')).values_list('t').annotate(c=Count('_id'))

any help would be appreciated

Amir Ayat · Answer 1 · 2021-07-12T06:18:26.493

One solution is to use pymongo instead of djongo or nonrel engine, like this:

from rest_framework.decorators import api_view
from rest_framework.response import Response
from pymongo import MongoClient
from bson import json_util
import json


@api_view(['GET', 'POST'])
def get_topic(request):


client = MongoClient('localhost', 27017)
db = client['DB_name']
pymongo_tweet = db.appname_tweet

req_query = [
            {
                '$unwind': '$topic'
            }, {
                '$group': {
                    '_id': '$topic', 
                    'count': {
                        '$sum': 1
                    }
                }
            }, {
                '$sort': {
                    'count': -1
                }
            }
            ]

cursor = pymongo_tweet.aggregate(req_query)
cursor_list = list(cursor)


return Response(cursor_list)

Django Query to get count of all distinct values for column of mongodb ArrayField

1 Answers1