Fix ValueError for DRF fields if field value is blank

pictures/contrib/rest_framework.py

@@ -20,6 +20,8 @@ class PictureField(serializers.ReadOnlyField):
     """Read-only field for all aspect ratios and sizes of the image."""
 
     def to_representation(self, obj: PictureFieldFile):
+        if not obj:
+            return None
         payload = {
             "url": obj.url,
             "width": obj.width,

tests/contrib/test_rest_framework.py

@@ -168,6 +168,20 @@ def test_to_representation__raise_value_error(
 
         assert str(e.value) == "Invalid ratio: 21/11. Choices are: 1/1, 3/2, 16/9"
 
+    @pytest.mark.django_db
+    def test_to_representation__blank(self, rf, image_upload_file, settings):
+        settings.PICTURES["USE_PLACEHOLDERS"] = False
+
+        profile = models.Profile.objects.create()
+        request = rf.get("/")
+        request.GET._mutable = True
+        request.GET["picture_ratio"] = "21/11"
+        request.GET["picture_l"] = "3"
+        request.GET["picture_m"] = "4"
+        serializer = ProfileSerializer(profile, context={"request": request})
+
+        assert serializer.data["picture"] is None
+
     @pytest.mark.django_db
     def test_to_representation__with_container(self, rf, image_upload_file, settings):
         settings.PICTURES["USE_PLACEHOLDERS"] = False

tests/testapp/migrations/0005_alter_profile_picture.py

@@ -0,0 +1,27 @@
+# Generated by Django 3.2.19 on 2023-06-07 18:06
+
+from django.db import migrations
+import pictures.models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("testapp", "0004_jpegmodel"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="profile",
+            name="picture",
+            field=pictures.models.PictureField(
+                aspect_ratios=[None, "1/1", "3/2", "16/9"],
+                blank=True,
+                breakpoints={"l": 1200, "m": 992, "s": 768, "xl": 1400, "xs": 576},
+                container_width=1200,
+                file_types=["WEBP"],
+                grid_columns=12,
+                pixel_densities=[1, 2],
+                upload_to="testapp/profile/",
+            ),
+        ),
+    ]

tests/testapp/models.py

@@ -35,7 +35,9 @@ class JPEGModel(models.Model):
 class Profile(models.Model):
     name = models.CharField(max_length=100)
     picture = PictureField(
-        upload_to="testapp/profile/", aspect_ratios=[None, "1/1", "3/2", "16/9"]
+        upload_to="testapp/profile/",
+        aspect_ratios=[None, "1/1", "3/2", "16/9"],
+        blank=True,
     )
 
     def get_absolute_url(self):