Resolve #160 -- Add picture_processed signal

pictures/models.py

@@ -157,6 +157,7 @@ def delete_all(self):
                 self.name,
                 [],
                 [i.deconstruct() for i in self.get_picture_files_list()],
+                self.instance_name,
             )
 
     def update_all(self, other: PictureFieldFile | None = None):
@@ -171,8 +172,13 @@ def update_all(self, other: PictureFieldFile | None = None):
                 self.name,
                 [i.deconstruct() for i in new],
                 [i.deconstruct() for i in old],
+                self.instance_name,
             )
 
+    @property
+    def instance_name(self):
+        return f"{self.instance._meta.app_label}.{self.instance._meta.model_name}.{self.field.name}"
+
     @property
     def width(self):
         self._require_file()

pictures/signals.py

@@ -0,0 +1,3 @@
+import django.dispatch
+
+process_picture_done = django.dispatch.Signal()

pictures/tasks.py

@@ -2,10 +2,11 @@
 
 from typing import Protocol
 
+from django.apps import apps
 from django.db import transaction
 from PIL import Image
 
-from pictures import conf, utils
+from pictures import conf, signals, utils
 
 
 def noop(*args, **kwargs) -> None:
@@ -19,6 +20,7 @@ def __call__(
         file_name: str,
         new: list[tuple[str, list, dict]] | None = None,
         old: list[tuple[str, list, dict]] | None = None,
+        field: str = "",
     ) -> None: ...
 
 
@@ -27,6 +29,7 @@ def _process_picture(
     file_name: str,
     new: list[tuple[str, list, dict]] | None = None,
     old: list[tuple[str, list, dict]] | None = None,
+    field: str = "",
 ) -> None:
     new = new or []
     old = old or []
@@ -41,6 +44,21 @@ def _process_picture(
         picture = utils.reconstruct(*picture)
         picture.delete()
 
+    if field:
+        app_label, model_name, _ = field.split(".")
+        sender = apps.get_model(app_label=app_label, model_name=model_name)
+    else:
+        sender = _process_picture
+
+    signals.process_picture_done.send(
+        sender=sender,
+        storage=storage.deconstruct(),
+        file_name=file_name,
+        new=new,
+        old=old,
+        field=field,
+    )
+
 
 process_picture: PictureProcessor = _process_picture
 
@@ -57,21 +75,24 @@ def process_picture_with_dramatiq(
         file_name: str,
         new: list[tuple[str, list, dict]] | None = None,
         old: list[tuple[str, list, dict]] | None = None,
+        field: str = "",
     ) -> None:
-        _process_picture(storage, file_name, new, old)
+        _process_picture(storage, file_name, new, old, field)
 
     def process_picture(  # noqa: F811
         storage: tuple[str, list, dict],
         file_name: str,
         new: list[tuple[str, list, dict]] | None = None,
         old: list[tuple[str, list, dict]] | None = None,
+        field: str = "",
     ) -> None:
         transaction.on_commit(
             lambda: process_picture_with_dramatiq.send(
                 storage=storage,
                 file_name=file_name,
                 new=new,
                 old=old,
+                field=field,
             )
         )
 
@@ -91,14 +112,16 @@ def process_picture_with_celery(
         file_name: str,
         new: list[tuple[str, list, dict]] | None = None,
         old: list[tuple[str, list, dict]] | None = None,
+        field: str = "",
     ) -> None:
-        _process_picture(storage, file_name, new, old)
+        _process_picture(storage, file_name, new, old, field)
 
     def process_picture(  # noqa: F811
         storage: tuple[str, list, dict],
         file_name: str,
         new: list[tuple[str, list, dict]] | None = None,
         old: list[tuple[str, list, dict]] | None = None,
+        field: str = "",
     ) -> None:
         transaction.on_commit(
             lambda: process_picture_with_celery.apply_async(
@@ -107,6 +130,7 @@ def process_picture(  # noqa: F811
                     file_name=file_name,
                     new=new,
                     old=old,
+                    field=field,
                 ),
                 queue=conf.get_settings().QUEUE_NAME,
             )
@@ -125,20 +149,23 @@ def process_picture_with_django_rq(
         file_name: str,
         new: list[tuple[str, list, dict]] | None = None,
         old: list[tuple[str, list, dict]] | None = None,
+        field: str = "",
     ) -> None:
-        _process_picture(storage, file_name, new, old)
+        _process_picture(storage, file_name, new, old, field)
 
     def process_picture(  # noqa: F811
         storage: tuple[str, list, dict],
         file_name: str,
         new: list[tuple[str, list, dict]] | None = None,
         old: list[tuple[str, list, dict]] | None = None,
+        field: str = "",
     ) -> None:
         transaction.on_commit(
             lambda: process_picture_with_django_rq.delay(
                 storage=storage,
                 file_name=file_name,
                 new=new,
                 old=old,
+                field=field,
             )
         )

tests/test_signals.py

@@ -0,0 +1,71 @@
+from unittest.mock import Mock
+
+import pytest
+from django.apps import apps
+from django.dispatch import receiver
+
+from pictures import signals, tasks
+from tests.testapp.models import SimpleModel
+
+
+@pytest.mark.django_db
+def test_process_picture_sends_process_picture_done(image_upload_file):
+    obj = SimpleModel.objects.create(picture=image_upload_file)
+
+    handler = Mock()
+    signals.process_picture_done.connect(handler)
+
+    tasks._process_picture(
+        obj.picture.storage.deconstruct(),
+        obj.picture.name,
+        new=[i.deconstruct() for i in obj.picture.get_picture_files_list()],
+    )
+
+    handler.assert_called_once_with(
+        signal=signals.process_picture_done,
+        sender=tasks._process_picture,
+        storage=obj.picture.storage.deconstruct(),
+        file_name=obj.picture.name,
+        new=[i.deconstruct() for i in obj.picture.get_picture_files_list()],
+        old=[],
+        field="",
+    )
+
+
+@pytest.mark.django_db
+def test_process_picture_sends_process_picture_done_on_create(image_upload_file):
+    handler = Mock()
+    signals.process_picture_done.connect(handler)
+
+    obj = SimpleModel.objects.create(picture=image_upload_file)
+
+    handler.assert_called_once_with(
+        signal=signals.process_picture_done,
+        sender=SimpleModel,
+        storage=obj.picture.storage.deconstruct(),
+        file_name=obj.picture.name,
+        new=[i.deconstruct() for i in obj.picture.get_picture_files_list()],
+        old=[],
+        field="testapp.simplemodel.picture",
+    )
+
+
+@pytest.mark.django_db
+def test_processed_object_found(image_upload_file):
+    obj = SimpleModel.objects.create()
+
+    found_object = None
+
+    @receiver(signals.process_picture_done, sender=SimpleModel)
+    def handler(*, file_name, field, **__):
+        nonlocal found_object
+        app_label, model_name, field_name = field.split(".")
+        model = apps.get_model(app_label=app_label, model_name=model_name)
+
+        # Users can now modify the object that process_picture_done
+        # corresponds to
+        found_object = model.objects.get(**{field_name: file_name})
+
+    obj.picture.save("image.png", image_upload_file)
+
+    assert obj == found_object