fix: GraphQL Group filters using deleted associated objects

There was a specific case where using Django built-in lookups for
relationships doesn't work properly with the soft delete solution we
implemented with `django-safedelete`. According to the library
maintainers, it's a known limitation[1].

To work around this limitation, a customized filter set were created for
Group schema on GraphQL. This custom filter set implements the
adjustments expected to ignore soft deleted objects when filtering by
relationships (joins).

[1] - makinacorpus/django-safedelete#158

terraso_backend/apps/graphql/schema/groups.py

@@ -1,3 +1,4 @@
+import django_filters
 import graphene
 from django.conf import settings
 from graphene import relay
@@ -9,24 +10,40 @@
 from .commons import BaseDeleteMutation, BaseWriteMutation, TerrasoConnection
 
 
-class GroupNode(DjangoObjectType):
-    id = graphene.ID(source="pk", required=True)
+class GroupFilterSet(django_filters.FilterSet):
+    # TODO: members__email was kept for backward compatibility. Remove as soon
+    # as the web client be updated to use memberships__email filter
+    members__email = django_filters.CharFilter(method="filter_memberships_email")
+    memberships__email = django_filters.CharFilter(method="filter_memberships_email")
+    associated_landscapes__is_default_landscape_group = django_filters.BooleanFilter(
+        method="filter_associated_landscapes"
+    )
+    associated_landscapes__isnull = django_filters.BooleanFilter(
+        method="filter_associated_landscapes"
+    )
 
     class Meta:
         model = Group
-        filter_fields = {
+        fields = {
             "name": ["exact", "icontains", "istartswith"],
             "slug": ["exact", "icontains"],
             "description": ["icontains"],
-            "associations_as_parent__child_group": ["exact"],
-            "associations_as_child__parent_group": ["exact"],
-            "associations_as_parent__child_group__slug": ["icontains"],
-            "associations_as_child__parent_group__slug": ["icontains"],
-            "memberships": ["exact"],
-            "associated_landscapes__is_default_landscape_group": ["exact"],
-            "associated_landscapes": ["isnull"],
-            "members__email": ["exact"],
         }
+
+    def filter_memberships_email(self, queryset, name, value):
+        return queryset.filter(memberships__user__email=value, memberships__deleted_at__isnull=True)
+
+    def filter_associated_landscapes(self, queryset, name, value):
+        filters = {"associated_landscapes__deleted_at__isnull": True}
+        filters[name] = value
+        return queryset.filter(**filters)
+
+
+class GroupNode(DjangoObjectType):
+    id = graphene.ID(source="pk", required=True)
+
+    class Meta:
+        model = Group
         fields = (
             "name",
             "slug",
@@ -39,6 +56,7 @@ class Meta:
             "associations_as_child",
             "associated_landscapes",
         )
+        filterset_class = GroupFilterSet
         interfaces = (relay.Node,)
         connection_class = TerrasoConnection
 
@@ -102,8 +120,6 @@ def mutate_and_get_payload(cls, root, info, **kwargs):
 
         ff_check_permission_on = settings.FEATURE_FLAGS["CHECK_PERMISSIONS"]
         user_has_delete_permission = user.has_perm(Group.get_perm("delete"), obj=kwargs["id"])
-
         if ff_check_permission_on and not user_has_delete_permission:
             raise GraphQLValidationException("User has no permission to delete this data.")
-
         return super().mutate_and_get_payload(root, info, **kwargs)

terraso_backend/tests/graphql/test_groups_filters.py

@@ -0,0 +1,141 @@
+import pytest
+from mixer.backend.django import mixer
+
+from apps.core.models import Group, Membership
+
+pytestmark = pytest.mark.django_db
+
+
+def test_groups_filter_by_membership_user_ignores_deleted_memberships(client_query, memberships):
+    membership = memberships[0]
+    membership.delete()
+
+    response = client_query(
+        """
+        {groups(memberships_Email: "%s") {
+          edges {
+            node {
+              slug
+            }
+          }
+        }}
+        """
+        % membership.user.email
+    )
+    edges = response.json()["data"]["groups"]["edges"]
+
+    assert not edges
+
+
+def test_groups_filter_by_with_landscape_association(client_query, users, landscape_groups):
+    user = users[0]
+    default_group_association, common_group_association = landscape_groups
+    mixer.blend(Membership, user=user, group=default_group_association.group)
+    mixer.blend(Membership, user=user, group=common_group_association.group)
+
+    response = client_query(
+        """
+        {groups(
+          associatedLandscapes_Isnull: false,
+          memberships_Email: "%s"
+        ) {
+          edges {
+            node {
+              slug
+            }
+          }
+        }}
+        """
+        % user.email
+    )
+    edges = response.json()["data"]["groups"]["edges"]
+    groups_result = [edge["node"]["slug"] for edge in edges]
+
+    assert len(groups_result) == 2
+    assert default_group_association.group.slug in groups_result
+    assert common_group_association.group.slug in groups_result
+
+
+def test_groups_filter_by_with_landscape_association_ignores_deleted_associations(
+    client_query, users, landscape_groups
+):
+    user = users[0]
+    default_group_association, common_group_association = landscape_groups
+    mixer.blend(Membership, user=user, group=default_group_association.group)
+    mixer.blend(Membership, user=user, group=common_group_association.group)
+
+    default_group_association.delete()
+
+    response = client_query(
+        """
+        {groups(
+          associatedLandscapes_Isnull: false,
+          memberships_Email: "%s"
+        ) {
+          edges {
+            node {
+              slug
+            }
+          }
+        }}
+        """
+        % user.email
+    )
+    edges = response.json()["data"]["groups"]["edges"]
+    groups_result = [edge["node"]["slug"] for edge in edges]
+
+    assert len(groups_result) == 1
+
+
+def test_groups_filter_by_default_landscape_group(client_query, users, landscape_groups):
+    user = users[0]
+    default_group_association, common_group_association = landscape_groups
+    mixer.blend(Membership, user=user, group=default_group_association.group)
+    mixer.blend(Membership, user=user, group=common_group_association.group)
+
+    response = client_query(
+        """
+        {groups(
+          associatedLandscapes_IsDefaultLandscapeGroup: true,
+          memberships_Email: "%s"
+        ) {
+          edges {
+            node {
+              slug
+            }
+          }
+        }}
+        """
+        % user.email
+    )
+    edges = response.json()["data"]["groups"]["edges"]
+    groups_result = [edge["node"]["slug"] for edge in edges]
+
+    assert len(groups_result) == 1
+    assert default_group_association.group.slug in groups_result
+
+
+def test_groups_filter_by_without_landscape_association(client_query, users):
+    user = users[0]
+    group = mixer.blend(Group)
+    membership = mixer.blend(Membership, user=user, group=group)
+
+    response = client_query(
+        """
+        {groups(
+          associatedLandscapes_Isnull: true,
+          memberships_Email: "%s"
+        ) {
+          edges {
+            node {
+              slug
+            }
+          }
+        }}
+        """
+        % membership.user.email
+    )
+    edges = response.json()["data"]["groups"]["edges"]
+    groups_result = [edge["node"]["slug"] for edge in edges]
+    assert len(groups_result) == 1
+    assert groups_result[0] == group.slug