Fix #80 -- Address a crash on unrestricted select_related() usage.

Thanks @JiriKr for the report.

CHANGELOG.rst

@@ -1,3 +1,9 @@
+1.6.3
+=====
+:release-date: unreleased
+
+- Address a crash on unrestricted ``select_related()`` usage (#81)
+
 1.6.2
 =====
 :release-date: 2024-08-12

seal/query.py

@@ -2,18 +2,36 @@
 from operator import attrgetter
 
 from django.db import models
+from django.db.models.query_utils import select_related_descend
 
 cached_value_getter = attrgetter("get_cached_value")
 
 
-def get_select_related_getters(lookups, opts):
+def get_restricted_select_related_getters(lookups, opts):
     """Turn a select_related dict structure into a tree of attribute getters"""
     for lookup, nested_lookups in lookups.items():
         field = opts.get_field(lookup)
         lookup_opts = field.related_model._meta
         yield (
             cached_value_getter(field),
-            tuple(get_select_related_getters(nested_lookups, lookup_opts)),
+            tuple(get_restricted_select_related_getters(nested_lookups, lookup_opts)),
+        )
+
+
+def get_unrestricted_select_related_getters(opts, max_depth, cur_depth=1):
+    if cur_depth > max_depth:
+        return
+    for field in opts.fields:
+        if not select_related_descend(field, False, None, {}):
+            continue
+        related_model_meta = field.related_model._meta
+        yield (
+            cached_value_getter(field),
+            tuple(
+                get_unrestricted_select_related_getters(
+                    related_model_meta, max_depth=max_depth, cur_depth=cur_depth + 1
+                )
+            ),
         )
 
 
@@ -44,12 +62,22 @@ def _sealed_related_iterator(self, related_walker):
             yield obj
 
     def __iter__(self):
-        select_related = self.queryset.query.select_related
+        query = self.queryset.query
+        select_related = query.select_related
         if select_related:
             opts = self.queryset.model._meta
-            select_related_getters = tuple(
-                get_select_related_getters(self.queryset.query.select_related, opts)
-            )
+            if isinstance(select_related, dict):
+                select_related_getters = tuple(
+                    get_restricted_select_related_getters(
+                        self.queryset.query.select_related, opts
+                    )
+                )
+            else:
+                select_related_getters = tuple(
+                    get_unrestricted_select_related_getters(
+                        opts, max_depth=query.max_depth
+                    )
+                )
             related_walker = partial(
                 walk_select_relateds, getters=select_related_getters
             )

tests/models.py

@@ -26,7 +26,7 @@ class Location(SealableModel):
     related_locations = models.ManyToManyField("self")
 
 
-class Island(models.Model):
+class Island(SealableModel):
     # Explicitly avoid setting a related_name.
     location = models.ForeignKey(Location, on_delete=models.CASCADE)
 

tests/test_query.py

@@ -46,6 +46,7 @@ def setUpTestData(cls):
         cls.nickname = Nickname.objects.create(
             name="Jonathan Livingston", content_object=cls.gull
         )
+        cls.island = Island.objects.create(location=cls.location)
         tests_models = tuple(apps.get_app_config("tests").get_models())
         ContentType.objects.get_for_models(*tests_models, for_concrete_models=True)
 
@@ -182,6 +183,19 @@ def test_sealed_select_related_reverse_one_to_one(self):
         with self.assertRaises(SeaLion.gull.RelatedObjectDoesNotExist):
             instance.gull
 
+    def test_sealed_select_related_unrestricted(self):
+        instance = Island.objects.select_related().seal().get()
+        self.assertEqual(instance.location, self.location)
+        instance = SeaLion.objects.select_related().seal().get()
+        message = (
+            'Attempt to fetch related field "location" on sealed <SeaLion instance>'
+        )
+        with self.assertWarnsMessage(UnsealedAttributeAccess, message) as ctx:
+            # null=True relationships are not followed when using
+            # an unrestricted select_related()
+            instance.location
+        self.assertEqual(ctx.filename, __file__)
+
     def test_sealed_prefetch_related_reverse_one_to_one(self):
         instance = SeaLion.objects.prefetch_related("gull").seal().get()
         self.assertEqual(instance.gull, self.gull)
@@ -439,9 +453,8 @@ def test_sealed_prefetched_select_related_many_to_many(self):
             self.assertSequenceEqual(instance.location.climates.all(), [self.climate])
 
     def test_prefetch_without_related_name(self):
-        island = Island.objects.create(location=self.location)
         location = Location.objects.prefetch_related("island_set").seal().get()
-        self.assertSequenceEqual(location.island_set.all(), [island])
+        self.assertSequenceEqual(location.island_set.all(), [self.island])
 
     def test_prefetch_combine(self):
         with self.assertNumQueries(6):