From b8bff8a882a3f7d62ee7677a4a008a2823053c18 Mon Sep 17 00:00:00 2001
From: Joachim <joachim.robert@protonmail.com>
Date: Thu, 27 May 2021 21:09:57 +0200
Subject: [PATCH] Use field tracker to launch task on field change

---
 bookwyrm/models/book.py   |  8 ++++++--
 bookwyrm/models/site.py   |  7 +++++--
 bookwyrm/models/status.py | 10 ++++++++--
 bookwyrm/models/user.py   |  6 ++++--
 4 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/bookwyrm/models/book.py b/bookwyrm/models/book.py
index aa9a56017..398517bab 100644
--- a/bookwyrm/models/book.py
+++ b/bookwyrm/models/book.py
@@ -3,6 +3,7 @@ import re
 
 from django.db import models
 from django.dispatch import receiver
+from model_utils import FieldTracker
 from model_utils.managers import InheritanceManager
 
 from bookwyrm import activitypub
@@ -92,6 +93,7 @@ class Book(BookDataModel):
     published_date = fields.DateTimeField(blank=True, null=True)
 
     objects = InheritanceManager()
+    field_tracker = FieldTracker(fields=['authors', 'title', 'subtitle', 'cover'])
 
     @property
     def author_text(self):
@@ -304,7 +306,9 @@ def isbn_13_to_10(isbn_13):
 @receiver(models.signals.post_save, sender=Edition)
 # pylint: disable=unused-argument
 def preview_image(instance, *args, **kwargs):
-    updated_fields = kwargs["update_fields"]
+    changed_fields = {}
+    if instance.field_tracker:
+        changed_fields = instance.field_tracker.changed()
 
-    if not updated_fields or "preview_image" not in updated_fields:
+    if len(changed_fields) > 0:
         generate_edition_preview_image_task.delay(instance.id)
diff --git a/bookwyrm/models/site.py b/bookwyrm/models/site.py
index d0076dc63..c9c015e1e 100644
--- a/bookwyrm/models/site.py
+++ b/bookwyrm/models/site.py
@@ -6,6 +6,7 @@ from Crypto import Random
 from django.db import models, IntegrityError
 from django.dispatch import receiver
 from django.utils import timezone
+from model_utils import FieldTracker
 
 from bookwyrm.preview_images import generate_site_preview_image_task
 from bookwyrm.settings import DOMAIN
@@ -48,6 +49,8 @@ class SiteSettings(models.Model):
     admin_email = models.EmailField(max_length=255, null=True, blank=True)
     footer_item = models.TextField(null=True, blank=True)
 
+    field_tracker = FieldTracker(fields=['name', 'instance_tagline', 'logo'])
+
     @classmethod
     def get(cls):
         """gets the site settings db entry or defaults"""
@@ -130,7 +133,7 @@ class PasswordReset(models.Model):
 @receiver(models.signals.post_save, sender=SiteSettings)
 # pylint: disable=unused-argument
 def preview_image(instance, *args, **kwargs):
-    updated_fields = kwargs["update_fields"]
+    changed_fields = instance.field_tracker.changed()
 
-    if not updated_fields or "preview_image" not in updated_fields:
+    if len(changed_fields) > 0:
         generate_site_preview_image_task.delay()
diff --git a/bookwyrm/models/status.py b/bookwyrm/models/status.py
index c55cd8d69..feedc02a5 100644
--- a/bookwyrm/models/status.py
+++ b/bookwyrm/models/status.py
@@ -8,6 +8,7 @@ from django.db import models
 from django.dispatch import receiver
 from django.template.loader import get_template
 from django.utils import timezone
+from model_utils import FieldTracker
 from model_utils.managers import InheritanceManager
 
 from bookwyrm import activitypub
@@ -306,6 +307,8 @@ class Review(Status):
         max_digits=3,
     )
 
+    field_tracker = FieldTracker(fields=['rating'])
+
     @property
     def pure_name(self):
         """clarify review names for mastodon serialization"""
@@ -406,5 +409,8 @@ class Boost(ActivityMixin, Status):
 # pylint: disable=unused-argument
 def preview_image(instance, sender, *args, **kwargs):
     if sender in (Review, ReviewRating):
-        edition = instance.book
-        generate_edition_preview_image_task.delay(edition.id)
+        changed_fields = instance.field_tracker.changed()
+        
+        if len(changed_fields) > 0:
+            edition = instance.book
+            generate_edition_preview_image_task.delay(edition.id)
diff --git a/bookwyrm/models/user.py b/bookwyrm/models/user.py
index 2c4851520..f2c700b6c 100644
--- a/bookwyrm/models/user.py
+++ b/bookwyrm/models/user.py
@@ -9,6 +9,7 @@ from django.core.validators import MinValueValidator
 from django.dispatch import receiver
 from django.db import models
 from django.utils import timezone
+from model_utils import FieldTracker
 import pytz
 
 from bookwyrm import activitypub
@@ -122,6 +123,7 @@ class User(OrderedCollectionPageMixin, AbstractUser):
 
     name_field = "username"
     property_fields = [("following_link", "following")]
+    field_tracker = FieldTracker(fields=['name', 'avatar'])
 
     @property
     def following_link(self):
@@ -453,7 +455,7 @@ def get_remote_reviews(outbox):
 @receiver(models.signals.post_save, sender=User)
 # pylint: disable=unused-argument
 def preview_image(instance, *args, **kwargs):
-    updated_fields = kwargs["update_fields"]
+    changed_fields = instance.field_tracker.changed()
 
-    if not updated_fields or "preview_image" not in updated_fields:
+    if len(changed_fields) > 0:
         generate_user_preview_image_task.delay(instance.id)