Fix pagination using 'after'

Author: pcraciunoiu

graphene_django/fields.py

@@ -2,7 +2,10 @@
 
 import six
 from django.db.models.query import QuerySet
-from graphql_relay.connection.arrayconnection import connection_from_list_slice
+from graphql_relay.connection.arrayconnection import (
+    connection_from_list_slice,
+    get_offset_with_default,
+)
 from promise import Promise
 
 from graphene import NonNull
@@ -137,6 +140,9 @@ def resolve_connection(cls, connection, args, iterable, max_limit=None):
             list_length = len(iterable)
             list_slice_length = max_limit or list_length
 
+        after = get_offset_with_default(args.get("after"), -1) + 1
+        list_slice_length += after
+
         connection = connection_from_list_slice(
             iterable,
             args,

graphene_django/tests/test_query.py

@@ -1130,6 +1130,7 @@ def test_should_have_next_page(graphene_settings):
     graphene_settings.RELAY_CONNECTION_MAX_LIMIT = 4
     reporters = [Reporter(**kwargs) for kwargs in REPORTERS]
     Reporter.objects.bulk_create(reporters)
+    db_reporters = Reporter.objects.all()
 
     class ReporterType(DjangoObjectType):
         class Meta:
@@ -1144,10 +1145,11 @@ class Query(graphene.ObjectType):
     # See `arrayconnection.py::connection_from_list_slice`:
     # has_next_page=isinstance(first, int) and end_offset < upper_bound
     query = """
-        query AllReporters {
-            allReporters(first: 4) {
+        query AllReporters($first: Int, $after: String) {
+            allReporters(first: $first, after: $after) {
                 pageInfo {
                     hasNextPage
+                    endCursor
                 }
                 edges {
                     node {
@@ -1158,11 +1160,26 @@ class Query(graphene.ObjectType):
         }
     """
 
-    result = schema.execute(query)
+    result = schema.execute(query, variable_values=dict(first=4))
     assert not result.errors
     assert len(result.data["allReporters"]["edges"]) == 4
     assert result.data["allReporters"]["pageInfo"]["hasNextPage"]
 
+    last_result = result.data["allReporters"]["pageInfo"]["endCursor"]
+    result2 = schema.execute(query, variable_values=dict(first=4, after=last_result))
+    assert not result2.errors
+    assert len(result2.data["allReporters"]["edges"]) == 2
+    assert not result2.data["allReporters"]["pageInfo"]["hasNextPage"]
+    gql_reporters = result.data["allReporters"]["edges"] + result2.data["allReporters"]["edges"]
+
+    assert {
+        to_global_id("ReporterType", reporter.id)
+        for reporter in db_reporters
+    } == {
+        gql_reporter["node"]["id"]
+        for gql_reporter in gql_reporters
+    }
+
 
 def test_should_preserve_prefetch_related(django_assert_num_queries):
     class ReporterType(DjangoObjectType):