Adding counts to DjangoFilterConnectionField

DjangoFilterConnectionField() can be tricky to work with in cases where you wish to extend your schema. Fortunately, the solution is simple.

The trick here is to subclass Connection and declare a connection_class on your node type. In your Query declarations, DjangoFilterConnectionField will use that declared connection_class class seamlessly wherever it's defined.

You can now easily implement counts (or really anything) on your extended Connection class and use them in your queries, while retaining the built-in filtering that comes with DjangoFilterConnectionField:

from graphene import ObjectType, Connection, Node, Int
from graphene_django import DjangoObjectType
from graphene_django.filter import DjangoFilterConnectionField
from ..models import Place


class ExtendedConnection(Connection):
    class Meta:
        abstract = True

    total_count = Int()
    edge_count = Int()

    def resolve_total_count(root, info, **kwargs):
        return root.length
    def resolve_edge_count(root, info, **kwargs):
        return len(root.edges)


class PlaceType(DjangoObjectType):
    class Meta:
        model = Place
        filter_fields = {
            'id':  ['exact', 'icontains'],
            'name': ['exact', 'icontains', 'istartswith', 'iendswith'],
        }
        interfaces = (Node, )
        connection_class = ExtendedConnection


class Query(ObjectType):
    places = DjangoFilterConnectionField(PlaceType)

This allows, on this example schema, querying:

{
  places(first: 2, name_Icontains: "Dallas", after: "YXJyYXljb25uZWN0aW9uOjE1") {
    totalCount
    edgeCount
    edges {
      cursor
      node {
        id
        name
      }
    }
  }
}

Which returns:

{
  "data": {
    "places": {
      "totalCount": 23,
      "edgeCount": 2,
      "edges": [
        {
          "cursor": "YXJyYXljb25uZWN0aW9uOjE2",
          "node": {
            "id": "UGxhY2VUeXBlOjUxOA==",
            "name": "Dallas, Dallas, Texas, United States"
          }
        },
        {
          "cursor": "YXJyYXljb25uZWN0aW9uOjE3",
          "node": {
            "id": "UGxhY2VUeXBlOjU0Nw==",
            "name": "Election Precinct 4 Valley Creek, Dallas, Alabama, United States"
          }
        }
      ]
    }
  }
}