Fix #228 -- Skip migration for objects without files

pictures/migrations.py

@@ -56,7 +56,9 @@ def update_pictures(self, from_field: PictureField, to_model: type[models.Model]
             new_field_file.update_all(old_field_file)
 
     def from_picture_field(self, from_model: type[models.Model]):
-        for obj in from_model._default_manager.all().iterator():
+        for obj in from_model._default_manager.exclude(
+            Q(**{self.name: ""}) | Q(**{self.name: None})
+        ).iterator():
             field_file = getattr(obj, self.name)
             field_file.delete_all()
 
@@ -66,9 +68,13 @@ def to_picture_field(
         from_field = from_model._meta.get_field(self.name)
         if hasattr(from_field.attr_class, "delete_variations"):
             # remove obsolete django-stdimage variations
-            for obj in from_model._default_manager.all().iterator():
+            for obj in from_model._default_manager.exclude(
+                Q(**{self.name: ""}) | Q(**{self.name: None})
+            ).iterator():
                 field_file = getattr(obj, self.name)
                 field_file.delete_variations()
-        for obj in to_model._default_manager.all().iterator():
+        for obj in to_model._default_manager.exclude(
+            Q(**{self.name: ""}) | Q(**{self.name: None})
+        ).iterator():
             field_file = getattr(obj, self.name)
             field_file.save_all()

tests/test_migrations.py

@@ -171,6 +171,54 @@ class Meta:
 
         assert not luke.picture
 
+    @pytest.mark.django_db
+    def test_update_pictures__with_empty_pictures(
+        self, request, stub_worker, image_upload_file
+    ):
+        """Test that update_pictures skips objects with empty/null pictures."""
+
+        class ToModel(models.Model):
+            name = models.CharField(max_length=100)
+            picture = PictureField(
+                upload_to="testapp/profile/", aspect_ratios=[None, "21/9"], blank=True
+            )
+
+            class Meta:
+                app_label = request.node.name
+                db_table = "testapp_profile"
+
+        # Create profiles with different picture states
+        luke = Profile.objects.create(name="Luke", picture=image_upload_file)
+        leia = Profile.objects.create(name="Leia", picture="")
+        han = Profile.objects.create(name="Han", picture=None)
+        stub_worker.join()
+
+        path = luke.picture.aspect_ratios["16/9"]["AVIF"][100].path
+        assert path.exists()
+
+        migration = migrations.AlterPictureField("profile", "picture", PictureField())
+        from_field = Profile._meta.get_field("picture")
+
+        # This should not fail despite empty/null pictures
+        migration.update_pictures(from_field, ToModel)
+        stub_worker.join()
+
+        # Verify old path was deleted and new one was created for luke
+        assert not path.exists()
+        luke.refresh_from_db()
+        path = (
+            ToModel.objects.get(pk=luke.pk)
+            .picture.aspect_ratios["21/9"]["AVIF"][100]
+            .path
+        )
+        assert path.exists()
+
+        # Verify empty profiles still exist and remain empty
+        leia_profile = Profile.objects.get(pk=leia.pk)
+        assert not leia_profile.picture
+        han_profile = Profile.objects.get(pk=han.pk)
+        assert not han_profile.picture
+
     @pytest.mark.django_db
     def test_from_picture_field(self, stub_worker, image_upload_file):
         luke = Profile.objects.create(name="Luke", picture=image_upload_file)
@@ -182,6 +230,30 @@ def test_from_picture_field(self, stub_worker, image_upload_file):
         stub_worker.join()
         assert not path.exists()
 
+    @pytest.mark.django_db
+    def test_from_picture_field__with_empty_pictures(
+        self, stub_worker, image_upload_file
+    ):
+        """Test that from_picture_field skips objects with empty/null pictures."""
+        # Create profiles with different picture states
+        luke = Profile.objects.create(name="Luke", picture=image_upload_file)
+        Profile.objects.create(name="Leia", picture="")
+        Profile.objects.create(name="Han", picture=None)
+        stub_worker.join()
+
+        path = luke.picture.aspect_ratios["16/9"]["AVIF"][100].path
+        assert path.exists()
+
+        migration = migrations.AlterPictureField("profile", "picture", PictureField())
+        # This should not fail despite empty/null pictures
+        migration.from_picture_field(Profile)
+        stub_worker.join()
+
+        assert not path.exists()
+        # Verify other profiles still exist and weren't affected
+        assert Profile.objects.filter(name="Leia").exists()
+        assert Profile.objects.filter(name="Han").exists()
+
     @pytest.mark.django_db
     def test_to_picture_field(self, request, stub_worker, image_upload_file):
         class FromModel(models.Model):
@@ -234,6 +306,53 @@ class Meta:
         migration = migrations.AlterPictureField("profile", "picture", PictureField())
         migration.to_picture_field(FromModel, Profile)
 
+    @pytest.mark.django_db
+    def test_to_picture_field__with_empty_pictures(
+        self, request, stub_worker, image_upload_file
+    ):
+        """Test that to_picture_field skips objects with empty/null pictures."""
+
+        class FromModel(models.Model):
+            picture = models.ImageField(blank=True)
+
+            class Meta:
+                app_label = request.node.name
+                db_table = "testapp_profile"
+
+        class ToModel(models.Model):
+            name = models.CharField(max_length=100)
+            picture = models.ImageField(upload_to="testapp/profile/", blank=True)
+
+            class Meta:
+                app_label = request.node.name
+                db_table = "testapp_profile"
+
+        # Create profiles with different picture states
+        luke = ToModel.objects.create(name="Luke", picture=image_upload_file)
+        leia = ToModel.objects.create(name="Leia", picture="")
+        han = ToModel.objects.create(name="Han", picture=None)
+        stub_worker.join()
+
+        migration = migrations.AlterPictureField("profile", "picture", PictureField())
+        # This should not fail despite empty/null pictures
+        migration.to_picture_field(FromModel, Profile)
+        stub_worker.join()
+
+        luke.refresh_from_db()
+        # Verify only luke's picture was processed
+        path = (
+            Profile.objects.get(pk=luke.pk)
+            .picture.aspect_ratios["16/9"]["AVIF"][100]
+            .path
+        )
+        assert path.exists()
+
+        # Verify empty profiles still exist
+        leia_profile = Profile.objects.get(pk=leia.pk)
+        assert not leia_profile.picture
+        han_profile = Profile.objects.get(pk=han.pk)
+        assert not han_profile.picture
+
     @pytest.mark.django_db
     def test_to_picture_field__from_stdimage(
         self, request, stub_worker, image_upload_file