Fixes #4076: Recommendations from collections.
[wolnelektury.git] / src / catalogue / models / book.py
index dc6ba50..8b5ac63 100644 (file)
@@ -1,34 +1,33 @@
-# -*- coding: utf-8 -*-
 # This file is part of Wolnelektury, licensed under GNU Affero GPLv3 or later.
 # Copyright © Fundacja Nowoczesna Polska. See NOTICE for more information.
 #
 from collections import OrderedDict
+import json
+from datetime import date, timedelta
 from random import randint
 import os.path
 import re
-import urllib
+from urllib.request import urlretrieve
 from django.conf import settings
 from django.db import connection, models, transaction
-from django.db.models import permalink
 import django.dispatch
 from django.contrib.contenttypes.fields import GenericRelation
-from django.core.urlresolvers import reverse
+from django.urls import reverse
 from django.utils.translation import ugettext_lazy as _, get_language
 from django.utils.deconstruct import deconstructible
-import jsonfield
 from fnpdjango.storage import BofhFileSystemStorage
-from ssify import flush_ssi_includes
 
+from librarian.cover import WLCover
 from librarian.html import transform_abstrakt
 from newtagging import managers
 from catalogue import constants
 from catalogue.fields import EbookField
 from catalogue.models import Tag, Fragment, BookMedia
-from catalogue.utils import create_zip, gallery_url, gallery_path, split_tags
+from catalogue.utils import create_zip, gallery_url, gallery_path, split_tags, get_random_hash
 from catalogue.models.tag import prefetched_relations
 from catalogue import app_settings
 from catalogue import tasks
-from wolnelektury.utils import makedirs
+from wolnelektury.utils import makedirs, cached_render, clear_cached_renders
 
 bofh_storage = BofhFileSystemStorage()
 
@@ -46,6 +45,7 @@ _cover_upload_to = UploadToPath('book/cover/%s.jpg')
 _cover_thumb_upload_to = UploadToPath('book/cover_thumb/%s.jpg')
 _cover_api_thumb_upload_to = UploadToPath('book/cover_api_thumb/%s.jpg')
 _simple_cover_upload_to = UploadToPath('book/cover_simple/%s.jpg')
+_cover_ebookpoint_upload_to = UploadToPath('book/cover_ebookpoint/%s.jpg')
 
 
 def _ebook_upload_to(upload_path):
@@ -57,7 +57,7 @@ class Book(models.Model):
     title = models.CharField(_('title'), max_length=32767)
     sort_key = models.CharField(_('sort key'), max_length=120, db_index=True, editable=False)
     sort_key_author = models.CharField(
-        _('sort key by author'), max_length=120, db_index=True, editable=False, default=u'')
+        _('sort key by author'), max_length=120, db_index=True, editable=False, default='')
     slug = models.SlugField(_('slug'), max_length=120, db_index=True, unique=True)
     common_slug = models.SlugField(_('slug'), max_length=120, db_index=True)
     language = models.CharField(_('language code'), max_length=3, db_index=True, default=app_settings.DEFAULT_LANGUAGE)
@@ -66,11 +66,16 @@ class Book(models.Model):
     created_at = models.DateTimeField(_('creation date'), auto_now_add=True, db_index=True)
     changed_at = models.DateTimeField(_('change date'), auto_now=True, db_index=True)
     parent_number = models.IntegerField(_('parent number'), default=0)
-    extra_info = jsonfield.JSONField(_('extra information'), default={})
+    extra_info = models.TextField(_('extra information'), default='{}')
     gazeta_link = models.CharField(blank=True, max_length=240)
     wiki_link = models.CharField(blank=True, max_length=240)
     print_on_demand = models.BooleanField(_('print on demand'), default=False)
     recommended = models.BooleanField(_('recommended'), default=False)
+    audio_length = models.CharField(_('audio length'), blank=True, max_length=8)
+    preview = models.BooleanField(_('preview'), default=False)
+    preview_until = models.DateField(_('preview until'), blank=True, null=True)
+    preview_key = models.CharField(max_length=32, blank=True, null=True)
+    findable = models.BooleanField(_('findable'), default=True, db_index=True)
 
     # files generated during publication
     cover = EbookField(
@@ -78,26 +83,36 @@ class Book(models.Model):
         null=True, blank=True,
         upload_to=_cover_upload_to,
         storage=bofh_storage, max_length=255)
+    cover_etag = models.CharField(max_length=255, editable=False, default='', db_index=True)
     # Cleaner version of cover for thumbs
     cover_thumb = EbookField(
         'cover_thumb', _('cover thumbnail'),
         null=True, blank=True,
         upload_to=_cover_thumb_upload_to,
         max_length=255)
+    cover_thumb_etag = models.CharField(max_length=255, editable=False, default='', db_index=True)
     cover_api_thumb = EbookField(
         'cover_api_thumb', _('cover thumbnail for mobile app'),
         null=True, blank=True,
         upload_to=_cover_api_thumb_upload_to,
         max_length=255)
+    cover_api_thumb_etag = models.CharField(max_length=255, editable=False, default='', db_index=True)
     simple_cover = EbookField(
         'simple_cover', _('cover for mobile app'),
         null=True, blank=True,
         upload_to=_simple_cover_upload_to,
         max_length=255)
+    simple_cover_etag = models.CharField(max_length=255, editable=False, default='', db_index=True)
+    cover_ebookpoint = EbookField(
+        'cover_ebookpoint', _('cover for Ebookpoint'),
+        null=True, blank=True,
+        upload_to=_cover_ebookpoint_upload_to,
+        max_length=255)
+    cover_ebookpoint_etag = models.CharField(max_length=255, editable=False, default='', db_index=True)
     ebook_formats = constants.EBOOK_FORMATS
     formats = ebook_formats + ['html', 'xml']
 
-    parent = models.ForeignKey('self', blank=True, null=True, related_name='children')
+    parent = models.ForeignKey('self', models.CASCADE, blank=True, null=True, related_name='children')
     ancestor = models.ManyToManyField('self', blank=True, editable=False, related_name='descendant', symmetrical=False)
 
     cached_author = models.CharField(blank=True, max_length=240, db_index=True)
@@ -111,7 +126,7 @@ class Book(models.Model):
     html_built = django.dispatch.Signal()
     published = django.dispatch.Signal()
 
-    short_html_url_name = 'catalogue_book_short'
+    SORT_KEY_SEP = '$'
 
     class AlreadyExists(Exception):
         pass
@@ -122,9 +137,12 @@ class Book(models.Model):
         verbose_name_plural = _('books')
         app_label = 'catalogue'
 
-    def __unicode__(self):
+    def __str__(self):
         return self.title
 
+    def get_extra_info_json(self):
+        return json.loads(self.extra_info or '{}')
+
     def get_initial(self):
         try:
             return re.search(r'\w', self.title, re.U).group(0)
@@ -134,6 +152,15 @@ class Book(models.Model):
     def authors(self):
         return self.tags.filter(category='author')
 
+    def epochs(self):
+        return self.tags.filter(category='epoch')
+
+    def genres(self):
+        return self.tags.filter(category='genre')
+
+    def kinds(self):
+        return self.tags.filter(category='kind')
+
     def tag_unicode(self, category):
         relations = prefetched_relations(self, category)
         if relations:
@@ -147,8 +174,23 @@ class Book(models.Model):
     def author_unicode(self):
         return self.cached_author
 
+    def kind_unicode(self):
+        return self.tag_unicode('kind')
+
+    def epoch_unicode(self):
+        return self.tag_unicode('epoch')
+
+    def genre_unicode(self):
+        return self.tag_unicode('genre')
+
+    def translators(self):
+        translators = self.get_extra_info_json().get('translators') or []
+        return [
+            '\xa0'.join(reversed(translator.split(', ', 1))) for translator in translators
+        ]
+
     def translator(self):
-        translators = self.extra_info.get('translators')
+        translators = self.get_extra_info_json().get('translators')
         if not translators:
             return None
         if len(translators) > 3:
@@ -156,38 +198,48 @@ class Book(models.Model):
             others = ' i inni'
         else:
             others = ''
-        return ', '.join(u'\xa0'.join(reversed(translator.split(', ', 1))) for translator in translators) + others
+        return ', '.join('\xa0'.join(reversed(translator.split(', ', 1))) for translator in translators) + others
 
     def cover_source(self):
-        return self.extra_info.get('cover_source', self.parent.cover_source() if self.parent else '')
+        return self.get_extra_info_json().get('cover_source', self.parent.cover_source() if self.parent else '')
+
+    @property
+    def isbn_pdf(self):
+        return self.get_extra_info_json().get('isbn_pdf')
+
+    @property
+    def isbn_epub(self):
+        return self.get_extra_info_json().get('isbn_epub')
+
+    @property
+    def isbn_mobi(self):
+        return self.get_extra_info_json().get('isbn_mobi')
+
 
     def save(self, force_insert=False, force_update=False, **kwargs):
         from sortify import sortify
 
         self.sort_key = sortify(self.title)[:120]
-        self.title = unicode(self.title)  # ???
+        self.title = str(self.title)  # ???
 
         try:
             author = self.authors().first().sort_key
         except AttributeError:
-            author = u''
+            author = ''
         self.sort_key_author = author
 
         self.cached_author = self.tag_unicode('author')
-        self.has_audience = 'audience' in self.extra_info
+        self.has_audience = 'audience' in self.get_extra_info_json()
+
+        if self.preview and not self.preview_key:
+            self.preview_key = get_random_hash(self.slug)[:32]
 
         ret = super(Book, self).save(force_insert, force_update, **kwargs)
 
         return ret
 
-    @permalink
     def get_absolute_url(self):
-        return 'catalogue.views.book_detail', [self.slug]
-
-    @staticmethod
-    @permalink
-    def create_url(slug):
-        return 'catalogue.views.book_detail', [slug]
+        return reverse('book_detail', args=[self.slug])
 
     def gallery_path(self):
         return gallery_path(self.slug)
@@ -195,6 +247,41 @@ class Book(models.Model):
     def gallery_url(self):
         return gallery_url(self.slug)
 
+    def get_first_text(self):
+        if self.html_file:
+            return self
+        child = self.children.all().order_by('parent_number').first()
+        if child is not None:
+            return child.get_first_text()
+
+    def get_last_text(self):
+        if self.html_file:
+            return self
+        child = self.children.all().order_by('parent_number').last()
+        if child is not None:
+            return child.get_last_text()
+
+    def get_prev_text(self):
+        if not self.parent:
+            return None
+        sibling = self.parent.children.filter(parent_number__lt=self.parent_number).order_by('-parent_number').first()
+        if sibling is not None:
+            return sibling.get_last_text()
+        return self.parent.get_prev_text()
+
+    def get_next_text(self):
+        if not self.parent:
+            return None
+        sibling = self.parent.children.filter(parent_number__gt=self.parent_number).order_by('parent_number').first()
+        if sibling is not None:
+            return sibling.get_first_text()
+        return self.parent.get_next_text()
+
+    def get_siblings(self):
+        if not self.parent:
+            return []
+        return self.parent.children.all().order_by('parent_number')
+
     @property
     def name(self):
         return self.title
@@ -208,6 +295,36 @@ class Book(models.Model):
     def is_foreign(self):
         return self.language_code() != settings.LANGUAGE_CODE
 
+    def set_audio_length(self):
+        length = self.get_audio_length()
+        if length > 0:
+            self.audio_length = self.format_audio_length(length)
+            self.save()
+
+    @staticmethod
+    def format_audio_length(seconds):
+        """
+        >>> Book.format_audio_length(1)
+        '0:01'
+        >>> Book.format_audio_length(3661)
+        '1:01:01'
+        """
+        if seconds < 60*60:
+            minutes = seconds // 60
+            seconds = seconds % 60
+            return '%d:%02d' % (minutes, seconds)
+        else:
+            hours = seconds // 3600
+            minutes = seconds % 3600 // 60
+            seconds = seconds % 60
+            return '%d:%02d:%02d' % (hours, minutes, seconds)
+
+    def get_audio_length(self):
+        total = 0
+        for media in self.get_mp3() or ():
+            total += app_settings.GET_MP3_LENGTH(media.file.path)
+        return int(total)
+
     def has_media(self, type_):
         if type_ in Book.formats:
             return bool(getattr(self, "%s_file" % type_))
@@ -238,24 +355,54 @@ class Book(models.Model):
     def get_daisy(self):
         return self.get_media("daisy")
 
+    def media_url(self, format_):
+        media = self.get_media(format_)
+        if media:
+            if self.preview:
+                return reverse('embargo_link', kwargs={'key': self.preview_key, 'slug': self.slug, 'format_': format_})
+            else:
+                return media.url
+        else:
+            return None
+
+    def html_url(self):
+        return self.media_url('html')
+
+    def pdf_url(self):
+        return self.media_url('pdf')
+
+    def epub_url(self):
+        return self.media_url('epub')
+
+    def mobi_url(self):
+        return self.media_url('mobi')
+
+    def txt_url(self):
+        return self.media_url('txt')
+
+    def fb2_url(self):
+        return self.media_url('fb2')
+
+    def xml_url(self):
+        return self.media_url('xml')
+
     def has_description(self):
         return len(self.description) > 0
     has_description.short_description = _('description')
     has_description.boolean = True
 
-    # ugly ugly ugly
     def has_mp3_file(self):
-        return bool(self.has_media("mp3"))
+        return self.has_media("mp3")
     has_mp3_file.short_description = 'MP3'
     has_mp3_file.boolean = True
 
     def has_ogg_file(self):
-        return bool(self.has_media("ogg"))
+        return self.has_media("ogg")
     has_ogg_file.short_description = 'OGG'
     has_ogg_file.boolean = True
 
     def has_daisy_file(self):
-        return bool(self.has_media("daisy"))
+        return self.has_media("daisy")
     has_daisy_file.short_description = 'DAISY'
     has_daisy_file.boolean = True
 
@@ -268,11 +415,11 @@ class Book(models.Model):
         projects = set()
         for mp3 in self.media.filter(type='mp3').iterator():
             # ogg files are always from the same project
-            meta = mp3.extra_info
+            meta = mp3.get_extra_info_json()
             project = meta.get('project')
             if not project:
                 # temporary fallback
-                project = u'CzytamySłuchając'
+                project = 'CzytamySłuchając'
 
             projects.add((project, meta.get('funded_by', '')))
 
@@ -305,12 +452,12 @@ class Book(models.Model):
     def zip_format(format_):
         def pretty_file_name(book):
             return "%s/%s.%s" % (
-                book.extra_info['author'],
+                book.get_extra_info_json()['author'],
                 book.slug,
                 format_)
 
         field_name = "%s_file" % format_
-        books = Book.objects.filter(parent=None).exclude(**{field_name: ""})
+        books = Book.objects.filter(parent=None).exclude(**{field_name: ""}).exclude(preview=True).exclude(findable=False)
         paths = [(pretty_file_name(b), getattr(b, field_name).path) for b in books.iterator()]
         return create_zip(paths, app_settings.FORMAT_ZIPS[format_])
 
@@ -320,6 +467,8 @@ class Book(models.Model):
         return create_zip(paths, "%s_%s" % (self.slug, format_))
 
     def search_index(self, book_info=None, index=None, index_tags=True, commit=True):
+        if not self.findable:
+            return
         if index is None:
             from search.index import Index
             index = Index()
@@ -329,10 +478,11 @@ class Book(models.Model):
                 index.index_tags()
             if commit:
                 index.index.commit()
-        except Exception, e:
+        except Exception as e:
             index.index.rollback()
             raise e
 
+    # will make problems in conjunction with paid previews
     def download_pictures(self, remote_gallery_url):
         gallery_path = self.gallery_path()
         # delete previous files, so we don't include old files in ebooks
@@ -346,10 +496,10 @@ class Book(models.Model):
             for ilustr in ilustr_elements:
                 ilustr_src = ilustr.get('src')
                 ilustr_path = os.path.join(gallery_path, ilustr_src)
-                urllib.urlretrieve('%s/%s' % (remote_gallery_url, ilustr_src), ilustr_path)
+                urlretrieve('%s/%s' % (remote_gallery_url, ilustr_src), ilustr_path)
 
     def load_abstract(self):
-        abstract = self.wldocument().edoc.getroot().find('.//abstrakt')
+        abstract = self.wldocument(parse_dublincore=False).edoc.getroot().find('.//abstrakt')
         if abstract is not None:
             self.abstract = transform_abstrakt(abstract)
         else:
@@ -373,7 +523,7 @@ class Book(models.Model):
 
     @classmethod
     def from_text_and_meta(cls, raw_file, book_info, overwrite=False, dont_build=None, search_index=True,
-                           search_index_tags=True, remote_gallery_url=None):
+                           search_index_tags=True, remote_gallery_url=None, days=0, findable=True):
         if dont_build is None:
             dont_build = set()
         dont_build = set.union(set(dont_build), set(app_settings.DONT_BUILD))
@@ -396,6 +546,9 @@ class Book(models.Model):
         if created:
             book_shelves = []
             old_cover = None
+            book.preview = bool(days)
+            if book.preview:
+                book.preview_until = date.today() + timedelta(days)
         else:
             if not overwrite:
                 raise Book.AlreadyExists(_('Book %s already exists') % book_slug)
@@ -405,14 +558,17 @@ class Book(models.Model):
 
         # Save XML file
         book.xml_file.save('%s.xml' % book.slug, raw_file, save=False)
+        if book.preview:
+            book.xml_file.set_readable(False)
 
+        book.findable = findable
         book.language = book_info.language
         book.title = book_info.title
         if book_info.variant_of:
             book.common_slug = book_info.variant_of.slug
         else:
             book.common_slug = book.slug
-        book.extra_info = book_info.to_dict()
+        book.extra_info = json.dumps(book_info.to_dict())
         book.load_abstract()
         book.save()
 
@@ -424,6 +580,7 @@ class Book(models.Model):
                 tag.save()
 
         book.tags = set(meta_tags + book_shelves)
+        book.save()  # update sort_key_author
 
         cover_changed = old_cover != book.cover_info()
         obsolete_children = set(b for b in book.children.all()
@@ -458,6 +615,7 @@ class Book(models.Model):
             book.cover_thumb.build_delay()
             book.cover_api_thumb.build_delay()
             book.simple_cover.build_delay()
+            book.cover_ebookpoint.build_delay()
 
         # Build HTML and ebooks.
         book.html_file.build_delay()
@@ -469,13 +627,12 @@ class Book(models.Model):
             if format_ not in dont_build:
                 getattr(book, '%s_file' % format_).build_delay()
 
-        if not settings.NO_SEARCH_INDEX and search_index:
+        if not settings.NO_SEARCH_INDEX and search_index and findable:
             tasks.index_book.delay(book.id, book_info=book_info, index_tags=search_index_tags)
 
         for child in notify_cover_changed:
             child.parent_cover_changed()
 
-        book.save()  # update sort_key_author
         book.update_popularity()
         cls.published.send(sender=cls, instance=book)
         return book
@@ -513,23 +670,9 @@ class Book(models.Model):
                     b.ancestor.add(parent)
                     parent = parent.parent
 
-    def flush_includes(self, languages=True):
-        if not languages:
-            return
-        if languages is True:
-            languages = [lc for (lc, _ln) in settings.LANGUAGES]
-        flush_ssi_includes([
-            template % (self.pk, lang)
-            for template in [
-                '/katalog/b/%d/mini.%s.html',
-                '/katalog/b/%d/mini_nolink.%s.html',
-                '/katalog/b/%d/short.%s.html',
-                '/katalog/b/%d/wide.%s.html',
-                '/api/include/book/%d.%s.json',
-                '/api/include/book/%d.%s.xml',
-                ]
-            for lang in languages
-            ])
+    def clear_cache(self):
+        clear_cached_renders(self.mini_box)
+        clear_cached_renders(self.mini_box_nolink)
 
     def cover_info(self, inherit=True):
         """Returns a dictionary to serve as fallback for BookInfo.
@@ -539,7 +682,7 @@ class Book(models.Model):
         need = False
         info = {}
         for field in ('cover_url', 'cover_by', 'cover_source'):
-            val = self.extra_info.get(field)
+            val = self.get_extra_info_json().get(field)
             if val:
                 info[field] = val
             else:
@@ -571,7 +714,7 @@ class Book(models.Model):
 
     def other_versions(self):
         """Find other versions (i.e. in other languages) of the book."""
-        return type(self).objects.filter(common_slug=self.common_slug).exclude(pk=self.pk)
+        return type(self).objects.filter(common_slug=self.common_slug, findable=True).exclude(pk=self.pk)
 
     def parents(self):
         books = []
@@ -593,8 +736,8 @@ class Book(models.Model):
         return ', '.join(names)
 
     def publisher(self):
-        publisher = self.extra_info['publisher']
-        if isinstance(publisher, basestring):
+        publisher = self.get_extra_info_json()['publisher']
+        if isinstance(publisher, str):
             return publisher
         elif isinstance(publisher, list):
             return ', '.join(publisher)
@@ -608,7 +751,7 @@ class Book(models.Model):
 
         """
         objects = cls.tagged.with_all(tags)
-        return objects.exclude(ancestor__in=objects)
+        return objects.filter(findable=True).exclude(ancestor__in=objects)
 
     @classmethod
     def book_list(cls, book_filter=None):
@@ -619,7 +762,7 @@ class Book(models.Model):
         """
 
         books_by_parent = {}
-        books = cls.objects.order_by('parent_number', 'sort_key').only('title', 'parent', 'slug')
+        books = cls.objects.filter(findable=True).order_by('parent_number', 'sort_key').only('title', 'parent', 'slug', 'extra_info')
         if book_filter:
             books = books.filter(book_filter).distinct()
 
@@ -649,23 +792,23 @@ class Book(models.Model):
         return books_by_author, orphans, books_by_parent
 
     _audiences_pl = {
-        "SP": (1, u"szkoła podstawowa"),
-        "SP1": (1, u"szkoła podstawowa"),
-        "SP2": (1, u"szkoła podstawowa"),
-        "SP3": (1, u"szkoła podstawowa"),
-        "P": (1, u"szkoła podstawowa"),
-        "G": (2, u"gimnazjum"),
-        "L": (3, u"liceum"),
-        "LP": (3, u"liceum"),
+        "SP": (1, "szkoła podstawowa"),
+        "SP1": (1, "szkoła podstawowa"),
+        "SP2": (1, "szkoła podstawowa"),
+        "SP3": (1, "szkoła podstawowa"),
+        "P": (1, "szkoła podstawowa"),
+        "G": (2, "gimnazjum"),
+        "L": (3, "liceum"),
+        "LP": (3, "liceum"),
     }
 
     def audiences_pl(self):
-        audiences = self.extra_info.get('audiences', [])
+        audiences = self.get_extra_info_json().get('audiences', [])
         audiences = sorted(set([self._audiences_pl.get(a, (99, a)) for a in audiences]))
         return [a[1] for a in audiences]
 
     def stage_note(self):
-        stage = self.extra_info.get('stage')
+        stage = self.get_extra_info_json().get('stage')
         if stage and stage < '0.4':
             return (_('This work needs modernisation'),
                     reverse('infopage', args=['wymagajace-uwspolczesnienia']))
@@ -688,7 +831,10 @@ class Book(models.Model):
     def fragment_data(self):
         fragment = self.choose_fragment()
         if fragment:
-            return {'title': fragment.book.pretty_title(), 'html': fragment.get_short_text()}
+            return {
+                'title': fragment.book.pretty_title(),
+                'html': re.sub('</?blockquote[^>]*>', '', fragment.get_short_text()),
+            }
         else:
             return None
 
@@ -704,6 +850,35 @@ class Book(models.Model):
     def ridero_link(self):
         return 'https://ridero.eu/%s/books/wl_%s/' % (get_language(), self.slug.replace('-', '_'))
 
+    def like(self, user):
+        from social.utils import likes, get_set, set_sets
+        if not likes(user, self):
+            tag = get_set(user, '')
+            set_sets(user, self, [tag])
+
+    def unlike(self, user):
+        from social.utils import likes, set_sets
+        if likes(user, self):
+            set_sets(user, self, [])
+
+    def full_sort_key(self):
+        return self.SORT_KEY_SEP.join((self.sort_key_author, self.sort_key, str(self.id)))
+
+    def cover_color(self):
+        return WLCover.epoch_colors.get(self.get_extra_info_json().get('epoch'), '#000000')
+
+    @cached_render('catalogue/book_mini_box.html')
+    def mini_box(self):
+        return {
+            'book': self
+        }
+
+    @cached_render('catalogue/book_mini_box.html')
+    def mini_box_nolink(self):
+        return {
+            'book': self,
+            'no_link': True,
+        }
 
 def add_file_fields():
     for format_ in Book.formats:
@@ -721,10 +896,13 @@ def add_file_fields():
             blank=True,
             default=''
         ).contribute_to_class(Book, field_name)
+        if format_ != 'xml':
+            models.CharField(max_length=255, editable=False, default='', db_index=True).contribute_to_class(Book, f'{field_name}_etag')
+
 
 add_file_fields()
 
 
 class BookPopularity(models.Model):
-    book = models.OneToOneField(Book, related_name='popularity')
+    book = models.OneToOneField(Book, models.CASCADE, related_name='popularity')
     count = models.IntegerField(default=0, db_index=True)