fix: handle generated-values when calculating _initial model version

drf_kit/models/diff_models.py

@@ -1,6 +1,8 @@
 import contextlib
 import logging
 
+from django.db.models import GeneratedField
+
 from drf_kit.serializers import as_dict
 
 logger = logging.getLogger(__name__)
@@ -40,8 +42,18 @@ def _dict(self):
 
         # If there's any deferred field (i.e. lazy loading),
         # refresh the whole object at once, instead of letting `value_from_object` refresh one by one
-        # TODO: Lazily compute the diff only for the deferred fields
-        if self.get_deferred_fields():
+        # TODO: Lazily compute the diff only for the deferred fields, otherwise .only() will be useless
+        lazy_fields = []
+        deferred_fields = self.get_deferred_fields()
+        for field in self._meta.get_fields():
+            if isinstance(field, GeneratedField):
+                continue
+            if field.name in deferred_fields:
+                lazy_fields.append(field)
+
+        if lazy_fields:
+            # refresh_from_db() will populate the deferred fields, this is causing max-recursing error,
+            # so we refresh all of them at once
             self.refresh_from_db(fields=[field.attname for field in self._meta.concrete_fields])
 
         for field in self._meta.fields:

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "drf-kit"
-version = "1.42.2"
+version = "1.42.3"
 description = "DRF Toolkit"
 authors = ["Nilo Saude <[email protected]>"]
 packages = [

test_app/migrations/0013_wizard_minimum_age.py

@@ -0,0 +1,19 @@
+# Generated by Django 5.0.6 on 2024-07-08 20:29
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("test_app", "0012_beast_is_active"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="wizard",
+            name="minimum_age",
+            field=models.GeneratedField(
+                db_persist=True, expression=models.Value(11), output_field=models.IntegerField()
+            ),
+        ),
+    ]

test_app/models.py

@@ -1,6 +1,7 @@
 from django.contrib.postgres.constraints import ExclusionConstraint
 from django.contrib.postgres.fields import DateTimeRangeField, RangeOperators
 from django.db import models
+from django.db.models import Value
 
 from drf_kit.fields import SlugifyField
 from drf_kit.models import (
@@ -24,6 +25,11 @@ class Wizard(BaseModel):
         null=True,
         blank=True,
     )
+    minimum_age = models.GeneratedField(
+        expression=Value(11),
+        output_field=models.IntegerField(),
+        db_persist=True,
+    )
     is_half_blood = models.BooleanField(default=True)
     picture = models.FileField(
         **StoragePath.media_thumb(),

test_app/tests/tests_models/tests_diff_models.py

@@ -78,7 +78,8 @@ def test_updated_special_fields(self):
         self.assertEqual(new_url.removeprefix("/"), wizard._diff["picture"][1])
 
     def test_no_deferred_fields(self):
-        WizardFactory(name="Harry Potter", age=12)
+        with self.assertNumQueries(2):
+            WizardFactory(name="Harry Potter", age=12)
 
         with self.assertNumQueries(1):
             # 1 SELECT with only
@@ -92,7 +93,8 @@ def test_no_deferred_fields(self):
         self.assertFalse(wizard._has_changed)
 
     def test_deferred_fields(self):
-        WizardFactory(name="Harry Potter", age=12)
+        with self.assertNumQueries(2):
+            WizardFactory(name="Harry Potter", age=12)
 
         with self.assertNumQueries(2):
             # 1 SELECT with only