From bcc68c598b555f29ae10e4b6b6af4f6437c11fd9 Mon Sep 17 00:00:00 2001
From: Alexander Dusenbery <adusenbery@2u.com>
Date: Thu, 26 Sep 2024 15:26:23 -0400
Subject: [PATCH] checkpoint: field/property swaperoo, overwrite data from
 related restricted copy on read

---
 enterprise_catalog/apps/catalog/models.py | 35 +++++++++++++++++------
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/enterprise_catalog/apps/catalog/models.py b/enterprise_catalog/apps/catalog/models.py
index 8e4b2b12..82ef405d 100644
--- a/enterprise_catalog/apps/catalog/models.py
+++ b/enterprise_catalog/apps/catalog/models.py
@@ -1211,6 +1211,15 @@ class Meta:
         unique=True,
     )
 
+    @property
+    def books(self):
+        prefetch_qs = models.Prefetch(
+            'restricted_books',
+            queryset=RestrictedBook.objects.filter(library=self),
+            to_attr='overwritten_copy',
+        )
+        return self.book_set.prefetch_related(prefetch_qs)
+
     def __str__(self):
         return self.name
 
@@ -1226,7 +1235,8 @@ class Meta:
         unique=True,
     )
     libraries = models.ManyToManyField(Library)
-    data = JSONField(
+    _data = JSONField(
+        db_column='data',
         default={},
         blank=True,
         null=True,
@@ -1234,6 +1244,12 @@ class Meta:
         dump_kwargs={'indent': 4, 'cls': JSONEncoder, 'separators': (',', ':')},
     )
 
+    @property
+    def data(self):
+        if overwritten_copy := getattr(self, 'overwritten_copy', None):
+            return overwritten_copy[0]._data
+        return self._data
+
 
 class Book(AbstractBook):
     class Meta:
@@ -1280,11 +1296,14 @@ def __str__(self):
 
 boston_pl, _= Library.objects.get_or_create(name='Boston Public Library')
 quincy_pl, _ = Library.objects.get_or_create(name='Quincy Public Library')
-book, _ = Book.objects.get_or_create(title='Moby Dick', data={'ahab': 'dead'})
-restricted_book, _ = RestrictedBook.objects.get_or_create(library=boston_pl, parent_book=book, data={'ahab': 'alive', 'note': 'restricted copy owned only by BPL'})
-
-restricted_titles = RestrictedBook.objects.filter(library=boston_pl).values_list('title', flat=True)
-book_qs = Book.objects.filter(libraries__in=[boston_pl]).exclude(title__in=restricted_titles).only('title', 'data')
-restricted_qs = RestrictedBook.objects.filter(library=boston_pl).only('title', 'data')
-print(book_qs.union(restricted_qs))
+moby_dick, _ = Book.objects.get_or_create(title='Moby Dick', _data={'ahab': 'dead'})
+boston_pl.book_set.add(moby_dick)
+quincy_pl.book_set.add(moby_dick)
+ulysses, _ = Book.objects.get_or_create(title='Ulysses', _data={'bloom': 'walking'})
+boston_pl.book_set.add(ulysses)
+quincy_pl.book_set.add(ulysses)
+restricted_book, _ = RestrictedBook.objects.get_or_create(library=boston_pl, parent_book=moby_dic, _data={'ahab': 'alive', 'note': 'restricted copy owned only by BPL'})
+
+boston_pl.books.filter(title='Moby Dick')
+quincy_pl.books.filter(title='Moby Dick')
 """