support group by

Author: timgraham

django_mongodb_backend/compiler.py

@@ -53,7 +53,7 @@ def _get_column_from_expression(self, expr, alias):
         Create a column named `alias` from the given expression to hold the
         aggregate value.
         """
-        column_target = expr.output_field.__class__()
+        column_target = expr.output_field.clone()
         column_target.db_column = alias
         column_target.set_attributes_from_name(alias)
         return Col(self.collection_name, column_target)
@@ -81,7 +81,7 @@ def _prepare_expressions_for_pipeline(self, expression, target, annotation_group
             alias = (
                 f"__aggregation{next(annotation_group_idx)}" if sub_expr != expression else target
             )
-            column_target = sub_expr.output_field.__class__()
+            column_target = sub_expr.output_field.clone()
             column_target.db_column = alias
             column_target.set_attributes_from_name(alias)
             inner_column = Col(self.collection_name, column_target)

django_mongodb_backend/fields/embedded_model.py

@@ -1,4 +1,5 @@
 from django.core import checks
+from django.core.exceptions import FieldDoesNotExist
 from django.db import models
 from django.db.models.fields.related import lazy_related_operation
 from django.db.models.lookups import Transform
@@ -112,7 +113,8 @@ def get_transform(self, name):
         transform = super().get_transform(name)
         if transform:
             return transform
-        return KeyTransformFactory(name)
+        field = self.embedded_model._meta.get_field(name)
+        return KeyTransformFactory(name, field)
 
     def validate(self, value, model_instance):
         super().validate(value, model_instance)
@@ -134,9 +136,25 @@ def formfield(self, **kwargs):
 
 
 class KeyTransform(Transform):
-    def __init__(self, key_name, *args, **kwargs):
+    def __init__(self, key_name, ref_field, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.key_name = str(key_name)
+        self.ref_field = ref_field
+
+    def get_transform(self, name):
+        result = None
+        if isinstance(self.ref_field, EmbeddedModelField):
+            opts = self.ref_field.embedded_model._meta
+            new_field = opts.get_field(name)
+            result = KeyTransformFactory(name, new_field)
+        else:
+            if self.ref_field.get_transform(name) is None:
+                raise FieldDoesNotExist(
+                    f"{self.ref_field.model._meta.object_name}.{self.ref_field.name}"
+                    f" has no field named '{name}'"
+                )
+            result = KeyTransformFactory(name, self.ref_field)
+        return result
 
     def preprocess_lhs(self, compiler, connection):
         key_transforms = [self.key_name]
@@ -154,8 +172,9 @@ def as_mql(self, compiler, connection):
 
 
 class KeyTransformFactory:
-    def __init__(self, key_name):
+    def __init__(self, key_name, ref_field):
         self.key_name = key_name
+        self.ref_field = ref_field
 
     def __call__(self, *args, **kwargs):
-        return KeyTransform(self.key_name, *args, **kwargs)
+        return KeyTransform(self.key_name, self.ref_field, *args, **kwargs)

tests/model_fields_/test_embedded_model.py

@@ -1,5 +1,14 @@
+import operator
+
 from django.core.exceptions import ValidationError
 from django.db import models
+from django.db.models import (
+    ExpressionWrapper,
+    F,
+    IntegerField,
+    Max,
+    Sum,
+)
 from django.test import SimpleTestCase, TestCase
 from django.test.utils import isolate_apps
 
@@ -104,6 +113,46 @@ def test_nested(self):
         )
         self.assertCountEqual(Book.objects.filter(author__address__city="NYC"), [obj])
 
+    def truncate_ms(self, value):
+        """Truncate microsends to millisecond precision as supported by MongoDB."""
+        return value.replace(microsecond=(value.microsecond // 1000) * 1000)
+
+    def test_ordering_by_embedded_field(self):
+        query = Holder.objects.filter(data__integer__gt=3).order_by("-data__integer").values("pk")
+        expected = [{"pk": e.pk} for e in list(reversed(self.objs[4:]))]
+        self.assertSequenceEqual(query, expected)
+
+    def test_ordering_grouping_by_embedded_field(self):
+        expected = sorted(
+            (Holder.objects.create(data=Data(integer=x)) for x in range(6)),
+            key=lambda x: x.data.integer,
+        )
+        query = (
+            Holder.objects.annotate(
+                group=ExpressionWrapper(F("data__integer") + 5, output_field=IntegerField())
+            )
+            .values("group")
+            .annotate(max_auto_now=Max("data__auto_now"))
+            .order_by("data__integer")
+        )
+        query_response = [{**e, "max_auto_now": self.truncate_ms(e["max_auto_now"])} for e in query]
+        self.assertSequenceEqual(
+            query_response,
+            [
+                {"group": e.data.integer + 5, "max_auto_now": self.truncate_ms(e.data.auto_now)}
+                for e in expected
+            ],
+        )
+
+    def test_ordering_grouping_by_sum(self):
+        [Holder.objects.create(data=Data(integer=x)) for x in range(6)]
+        qs = (
+            Holder.objects.values("data__integer")
+            .annotate(sum=Sum("data__integer"))
+            .order_by("sum")
+        )
+        self.assertQuerySetEqual(qs, [0, 2, 4, 6, 8, 10], operator.itemgetter("sum"))
+
 
 @isolate_apps("model_fields_")
 class CheckTests(SimpleTestCase):