Implement composite member lookup

Closes #9

Author: OJFord

postgres_composite_types/composite_type.py

@@ -87,6 +87,19 @@ def __new__(cls, name, bases, attrs):
         new_cls = super().__new__(cls, name, bases, attrs)
         new_cls._meta = meta_obj
 
+        for _, field in new_cls._meta.fields:
+            new_cls.Field.register_lookup(
+                type(
+                    f"{name}{field.attname}Lookup",
+                    (models.Transform,),
+                    {
+                        "lookup_name": field.attname,
+                        "arity": 1,
+                        "template": f'(%(expressions)s)."{field.column}"',
+                    },
+                )
+            )
+
         meta_obj.model = new_cls
 
         return new_cls

tests/migrations/0001_initial.py

@@ -11,6 +11,7 @@
     DescriptorType,
     OptionalBits,
     Point,
+    RenamedMemberType,
     SimpleType,
 )
 
@@ -28,4 +29,5 @@ class Migration(migrations.Migration):
         Box.Operation(),
         DateRange.Operation(),
         DescriptorType.Operation(),
+        RenamedMemberType.Operation(),
     ]

tests/migrations/0002_models.py

@@ -7,7 +7,6 @@
 
 
 class Migration(migrations.Migration):
-
     initial = True
 
     dependencies = [
@@ -115,4 +114,10 @@ class Migration(migrations.Migration):
                 ("test_field", tests.models.SimpleTypeField()),
             ],
         ),
+        migrations.CreateModel(
+            name="RenamedMemberModel",
+            fields=[
+                ("field", tests.models.RenamedMemberTypeField()),
+            ],
+        ),
     ]

tests/models.py

@@ -123,3 +123,19 @@ class DescriptorModel(models.Model):
     """Has a composite type with a field implementing a custom descriptor"""
 
     field = DescriptorType.Field()
+
+
+class RenamedMemberType(CompositeType):
+    """Has a field with a different name in ORM vs db"""
+
+    class Meta:
+        db_type = "test_renamed_member"
+
+    orm_name = models.CharField(db_column="db_name", max_length=32)
+    other = models.BooleanField(default=False)
+
+
+class RenamedMemberModel(models.Model):
+    """Has a composite type with a member attr name that differs from the column name"""
+
+    field = RenamedMemberType.Field()

tests/test_more.py

@@ -1,11 +1,24 @@
 """
 Tests for composite fields in combination with other interesting fields.
 """
+import datetime
 
 from django.db.migrations.writer import MigrationWriter
 from django.test import TestCase
 
-from .models import Box, Card, DescriptorModel, DescriptorType, Hand, Item, Point
+from .models import (
+    Box,
+    Card,
+    DescriptorModel,
+    DescriptorType,
+    Hand,
+    Item,
+    Point,
+    RenamedMemberModel,
+    RenamedMemberType,
+    SimpleModel,
+    SimpleType,
+)
 
 
 class TestArrayFields(TestCase):
@@ -115,3 +128,35 @@ def test_set(self):
         model = DescriptorModel(field=DescriptorType(value=0))
         model.field.value = 14
         self.assertEqual(model.field.value, 42)
+
+
+class TestMemberLookup(TestCase):
+    """
+    Test filtering queryset on composite type members.
+    """
+
+    def test_value(self):
+        """Test finding a record by composite member value."""
+        t = SimpleType(a=1, b="β ☃", c=datetime.datetime(1985, 10, 26, 9, 0))
+        m = SimpleModel(test_field=t)
+        m.save()
+
+        self.assertEqual(SimpleModel.objects.get(test_field__a=1), m)
+
+    def test_comparison(self):
+        """Test finding a record by comparison on a composite member value."""
+        t = SimpleType(a=1, b="β ☃", c=datetime.datetime(1985, 10, 26, 9, 0))
+        m = SimpleModel(test_field=t)
+        m.save()
+        t.a = 3
+        SimpleModel.objects.create(test_field=t)
+
+        self.assertEqual(SimpleModel.objects.get(test_field__a__lt=2), m)
+
+    def test_renamed(self):
+        """Test finding a record by composite member value with a different ORM name."""
+        t = RenamedMemberType(orm_name="foo")
+        m = RenamedMemberModel(field=t)
+        m.save()
+
+        self.assertEqual(RenamedMemberModel.objects.get(field__orm_name="foo"), m)