X-Git-Url: https://git.mdrn.pl/wolnelektury.git/blobdiff_plain/552f54f1b01bd2bcc0bc83e5d24466086a863efa..bf8b3154e3a3d09be0d30516bf42a4652bcdedc8:/apps/catalogue/models.py?ds=sidebyside

diff --git a/apps/catalogue/models.py b/apps/catalogue/models.py
index 76de9d9d1..f2be7d1b9 100644
--- a/apps/catalogue/models.py
+++ b/apps/catalogue/models.py
@@ -11,7 +11,9 @@ from django.template.loader import render_to_string
 from django.utils.safestring import mark_safe
 from django.utils.translation import get_language
 from django.core.urlresolvers import reverse
-from datetime import datetime
+from django.db.models.signals import post_save, m2m_changed, pre_delete
+
+from django.conf import settings
 
 from newtagging.models import TagBase, tags_updated
 from newtagging import managers
@@ -19,6 +21,7 @@ from catalogue.fields import JSONField
 
 from librarian import dcparser, html, epub, NoDublinCore
 from mutagen import id3
+from slughifi import slughifi
 
 
 TAG_CATEGORIES = (
@@ -31,6 +34,12 @@ TAG_CATEGORIES = (
     ('book', _('book')),
 )
 
+MEDIA_FORMATS = (
+    ('odt', _('ODT file')),
+    ('mp3', _('MP3 file')),
+    ('ogg', _('OGG file')),
+    ('daisy', _('DAISY file')), 
+)
 
 class TagSubcategoryManager(models.Manager):
     def __init__(self, subcategory):
@@ -44,15 +53,14 @@ class TagSubcategoryManager(models.Manager):
 class Tag(TagBase):
     name = models.CharField(_('name'), max_length=50, db_index=True)
     slug = models.SlugField(_('slug'), max_length=120, db_index=True)
-    sort_key = models.SlugField(_('sort key'), max_length=120, db_index=True)
+    sort_key = models.CharField(_('sort key'), max_length=120, db_index=True)
     category = models.CharField(_('category'), max_length=50, blank=False, null=False,
         db_index=True, choices=TAG_CATEGORIES)
     description = models.TextField(_('description'), blank=True)
     main_page = models.BooleanField(_('main page'), default=False, db_index=True, help_text=_('Show tag on main page'))
 
     user = models.ForeignKey(User, blank=True, null=True)
-    book_count = models.IntegerField(_('book count'), blank=False, null=True)
-    death = models.IntegerField(_(u'year of death'), blank=True, null=True)
+    book_count = models.IntegerField(_('book count'), blank=True, null=True)
     gazeta_link = models.CharField(blank=True, max_length=240)
     wiki_link = models.CharField(blank=True, max_length=240)
 
@@ -87,17 +95,6 @@ class Tag(TagBase):
     has_description.short_description = _('description')
     has_description.boolean = True
 
-    def alive(self):
-        return self.death is None
-
-    def in_pd(self):
-        """ tests whether an author is in public domain """
-        return self.death is not None and self.goes_to_pd() <= datetime.now().year
-
-    def goes_to_pd(self):
-        """ calculates the year of public domain entry for an author """
-        return self.death + 71 if self.death is not None else None
-
     def get_count(self):
         """ returns global book count for book tags, fragment count for themes """
 
@@ -159,40 +156,89 @@ class Tag(TagBase):
 
 
 # TODO: why is this hard-coded ?
-def book_upload_path(ext):
-    def get_dynamic_path(book, filename):
-        return 'lektura/%s.%s' % (book.slug, ext)
+def book_upload_path(ext=None, maxlen=100):
+    def get_dynamic_path(media, filename, ext=ext):
+        # how to put related book's slug here?
+        if not ext:
+            if media.type == 'daisy':
+                ext = 'daisy.zip'
+            else:
+                ext = media.type
+        if not media.name:
+            name = slughifi(filename.split(".")[0])
+        else:
+            name = slughifi(media.name)
+        return 'lektura/%s.%s' % (name[:maxlen-len('lektura/.%s' % ext)-4], ext)
     return get_dynamic_path
 
 
-class Book(models.Model):
-    title = models.CharField(_('title'), max_length=120)
-    slug = models.SlugField(_('slug'), max_length=120, unique=True, db_index=True)
-    description = models.TextField(_('description'), blank=True)
-    created_at = models.DateTimeField(_('creation date'), auto_now_add=True)
-    _short_html = models.TextField(_('short HTML'), editable=False)
-    parent_number = models.IntegerField(_('parent number'), default=0)
-    extra_info = JSONField(_('extra information'))
-    gazeta_link = models.CharField(blank=True, max_length=240)
-    wiki_link = models.CharField(blank=True, max_length=240)
+class BookMedia(models.Model):
+    type        = models.CharField(_('type'), choices=MEDIA_FORMATS, max_length="100")
+    name        = models.CharField(_('name'), max_length="100")
+    file        = models.FileField(_('file'), upload_to=book_upload_path())
+    uploaded_at = models.DateTimeField(_('creation date'), auto_now_add=True, editable=False)
+    extra_info  = JSONField(_('extra information'), default='{}')
 
+    def book_count(self):
+        return self.book_set.count()
+    book_count.short_description = _('book count')
 
-    # Formats
-    xml_file = models.FileField(_('XML file'), upload_to=book_upload_path('xml'), blank=True)
-    html_file = models.FileField(_('HTML file'), upload_to=book_upload_path('html'), blank=True)
-    pdf_file = models.FileField(_('PDF file'), upload_to=book_upload_path('pdf'), blank=True)
-    epub_file = models.FileField(_('EPUB file'), upload_to=book_upload_path('epub'), blank=True)
-    odt_file = models.FileField(_('ODT file'), upload_to=book_upload_path('odt'), blank=True)
-    txt_file = models.FileField(_('TXT file'), upload_to=book_upload_path('txt'), blank=True)
-    mp3_file = models.FileField(_('MP3 file'), upload_to=book_upload_path('mp3'), blank=True)
-    ogg_file = models.FileField(_('OGG file'), upload_to=book_upload_path('ogg'), blank=True)
-    daisy_file = models.FileField(_('DAISY file'), upload_to=book_upload_path('daisy.zip'), blank=True)
+    def books(self):
+        return mark_safe('<br/>'.join("<a href='%s'>%s</a>" % (reverse('admin:catalogue_book_change', args=[b.id]), b.title) for b in self.book_set.all()))
+    books.short_description = _('books')
 
-    parent = models.ForeignKey('self', blank=True, null=True, related_name='children')
+    def __unicode__(self):
+        return "%s (%s)" % (self.name, self.file.name.split("/")[-1])
 
-    objects = models.Manager()
-    tagged = managers.ModelTaggedItemManager(Tag)
-    tags = managers.TagDescriptor(Tag)
+    class Meta:
+        ordering            = ('type', 'name')
+        verbose_name        = _('book media')
+        verbose_name_plural = _('book media')
+
+    def save(self, force_insert=False, force_update=False, **kwargs):
+        media = super(BookMedia, self).save(force_insert, force_update, **kwargs)
+        if self.type == 'mp3':
+            file = self.file
+            extra_info = self.get_extra_info_value()
+            extra_info.update(self.get_mp3_info())
+            self.set_extra_info_value(extra_info)
+            media = super(BookMedia, self).save(force_insert, force_update, **kwargs)
+        return media
+
+    def get_mp3_info(self):
+        """Retrieves artist and director names from audio ID3 tags."""
+        try:
+            audio = id3.ID3(self.file.path)
+            artist_name = ', '.join(', '.join(tag.text) for tag in audio.getall('TPE1'))
+            director_name = ', '.join(', '.join(tag.text) for tag in audio.getall('TPE3'))
+        except:
+            artist_name = director_name = ''
+        return {'artist_name': artist_name, 'director_name': director_name}
+
+
+class Book(models.Model):
+    title         = models.CharField(_('title'), max_length=120)
+    slug          = models.SlugField(_('slug'), max_length=120, unique=True, db_index=True)
+    description   = models.TextField(_('description'), blank=True)
+    created_at    = models.DateTimeField(_('creation date'), auto_now_add=True)
+    _short_html   = models.TextField(_('short HTML'), editable=False)
+    parent_number = models.IntegerField(_('parent number'), default=0)
+    extra_info    = JSONField(_('extra information'))
+    gazeta_link   = models.CharField(blank=True, max_length=240)
+    wiki_link     = models.CharField(blank=True, max_length=240)
+    # files generated during publication
+    xml_file      = models.FileField(_('XML file'), upload_to=book_upload_path('xml'), blank=True)
+    html_file     = models.FileField(_('HTML file'), upload_to=book_upload_path('html'), blank=True)
+    pdf_file      = models.FileField(_('PDF file'), upload_to=book_upload_path('pdf'), blank=True)
+    epub_file     = models.FileField(_('EPUB file'), upload_to=book_upload_path('epub'), blank=True)    
+    txt_file      = models.FileField(_('TXT file'), upload_to=book_upload_path('txt'), blank=True)        
+    # other files
+    medias        = models.ManyToManyField(BookMedia, blank=True)
+    
+    parent        = models.ForeignKey('self', blank=True, null=True, related_name='children')
+    objects  = models.Manager()
+    tagged   = managers.ModelTaggedItemManager(Tag)
+    tags     = managers.TagDescriptor(Tag)
 
     _tag_counter = JSONField(null=True, editable=False)
     _theme_counter = JSONField(null=True, editable=False)
@@ -208,7 +254,7 @@ class Book(models.Model):
     def __unicode__(self):
         return self.title
 
-    def save(self, force_insert=False, force_update=False, reset_short_html=True, refresh_mp3=True, **kwargs):
+    def save(self, force_insert=False, force_update=False, reset_short_html=True, **kwargs):
         if reset_short_html:
             # Reset _short_html during save
             update = {}
@@ -218,16 +264,7 @@ class Book(models.Model):
             # Fragment.short_html relies on book's tags, so reset it here too
             self.fragments.all().update(**update)
 
-        book = super(Book, self).save(force_insert, force_update)
-
-        if refresh_mp3 and self.mp3_file:
-            print self.mp3_file, self.mp3_file.path
-            extra_info = self.get_extra_info_value()
-            extra_info.update(self.get_mp3_info())
-            self.set_extra_info_value(extra_info)
-            book = super(Book, self).save(force_insert, force_update)
-
-        return book
+        return super(Book, self).save(force_insert, force_update)
 
     @permalink
     def get_absolute_url(self):
@@ -245,10 +282,68 @@ class Book(models.Model):
         book_tag, created = Tag.objects.get_or_create(slug=slug, category='book')
         if created:
             book_tag.name = self.title[:50]
-            book_tag.sort_key = slug
+            book_tag.sort_key = self.title.lower()
             book_tag.save()
         return book_tag
 
+    def has_media(self, type):
+        if   type == 'xml':
+            if self.xml_file:
+                return True
+            else:
+                return False
+        elif type == 'html':
+            if self.html_file:
+                return True
+            else:
+                return False        
+        elif type == 'txt':
+            if self.txt_file:
+                return True
+            else:
+                return False        
+        elif type == 'pdf':
+            if self.pdf_file:
+                return True
+            else:
+                return False  
+        elif type == 'epub':
+            if self.epub_file:
+                return True
+            else:
+                return False                          
+        else:
+            if self.medias.filter(book=self, type=type).count() > 0:
+                return True
+            else:
+                return False
+
+    def get_media(self, type):
+        if self.has_media(type):
+            if   type == "xml":
+                return self.xml_file
+            elif type == "html":
+                return self.html_file
+            elif type == "epub":
+                return self.epub_file
+            elif type == "txt":
+                return self.txt_file
+            elif type == "pdf":
+                return self.pdf_file
+            else:                                             
+                return self.medias.filter(book=self, type=type)
+        else:
+            return None
+
+    def get_mp3(self):
+        return self.get_media("mp3")
+    def get_odt(self):
+        return self.get_media("odt")
+    def get_ogg(self):
+        return self.get_media("ogg")
+    def get_daisy(self):
+        return self.get_media("daisy")                       
+
     def short_html(self):
         key = '_short_html_%s' % get_language()
         short_html = getattr(self, key)
@@ -260,22 +355,18 @@ class Book(models.Model):
             tags = [mark_safe(u'<a href="%s">%s</a>' % (tag.get_absolute_url(), tag.name)) for tag in tags]
 
             formats = []
-            if self.html_file:
+            # files generated during publication               
+            if self.has_media("html"):
                 formats.append(u'<a href="%s">%s</a>' % (reverse('book_text', kwargs={'slug': self.slug}), _('Read online')))
-            if self.pdf_file:
-                formats.append(u'<a href="%s">PDF</a>' % self.pdf_file.url)
-            if self.root_ancestor.epub_file:
-                formats.append(u'<a href="%s">EPUB</a>' % self.root_ancestor.epub_file.url)
-            if self.odt_file:
-                formats.append(u'<a href="%s">ODT</a>' % self.odt_file.url)
-            if self.txt_file:
-                formats.append(u'<a href="%s">TXT</a>' % self.txt_file.url)
-            if self.mp3_file:
-                formats.append(u'<a href="%s">MP3</a>' % self.mp3_file.url)
-            if self.ogg_file:
-                formats.append(u'<a href="%s">OGG</a>' % self.ogg_file.url)
-            if self.daisy_file:
-                formats.append(u'<a href="%s">DAISY</a>' % self.daisy_file.url)
+            if self.has_media("pdf"):
+                formats.append(u'<a href="%s">PDF</a>' % self.get_media('pdf').url)
+            if self.root_ancestor.has_media("epub"):
+                formats.append(u'<a href="%s">EPUB</a>' % self.root_ancestor.get_media('epub').url)
+            if self.has_media("txt"):
+                formats.append(u'<a href="%s">TXT</a>' % self.get_media('txt').url)
+            # other files
+            for m in self.medias.order_by('type'):
+                formats.append(u'<a href="%s">%s</a>' % (m.file.url, m.type.upper()))
 
             formats = [mark_safe(format) for format in formats]
 
@@ -297,18 +388,12 @@ class Book(models.Model):
         return self._root_ancestor
 
 
-    def get_mp3_info(self):
-        """Retrieves artist and director names from audio ID3 tags."""
-        audio = id3.ID3(self.mp3_file.path)
-        artist_name = ', '.join(', '.join(tag.text) for tag in audio.getall('TPE1'))
-        director_name = ', '.join(', '.join(tag.text) for tag in audio.getall('TPE3'))
-        return {'artist_name': artist_name, 'director_name': director_name}
-
     def has_description(self):
         return len(self.description) > 0
     has_description.short_description = _('description')
     has_description.boolean = True
 
+    # ugly ugly ugly
     def has_pdf_file(self):
         return bool(self.pdf_file)
     has_pdf_file.short_description = 'PDF'
@@ -319,16 +404,36 @@ class Book(models.Model):
     has_epub_file.short_description = 'EPUB'
     has_epub_file.boolean = True
 
-    def has_odt_file(self):
-        return bool(self.odt_file)
-    has_odt_file.short_description = 'ODT'
-    has_odt_file.boolean = True
+    def has_txt_file(self):
+        return bool(self.txt_file)
+    has_txt_file.short_description = 'HTML'
+    has_txt_file.boolean = True
 
     def has_html_file(self):
         return bool(self.html_file)
     has_html_file.short_description = 'HTML'
     has_html_file.boolean = True
 
+    def has_odt_file(self):
+        return bool(self.has_media("odt"))
+    has_odt_file.short_description = 'ODT'
+    has_odt_file.boolean = True
+
+    def has_mp3_file(self):
+        return bool(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"))
+    has_ogg_file.short_description = 'OGG'
+    has_ogg_file.boolean = True
+    
+    def has_daisy_file(self):
+        return bool(self.has_media("daisy"))
+    has_daisy_file.short_description = 'DAISY'
+    has_daisy_file.boolean = True    
+    
     def build_epub(self, remove_descendants=True):
         """ (Re)builds the epub file.
             If book has a parent, does nothing.
@@ -358,9 +463,8 @@ class Book(models.Model):
 
         epub_file = StringIO()
         try:
-            epub.transform(BookImportDocProvider(self), self.slug, epub_file)
-            self.epub_file.save('%s.epub' % self.slug, ContentFile(epub_file.getvalue()), save=False)
-            self.save()
+            epub.transform(BookImportDocProvider(self), self.slug, output_file=epub_file)
+            self.epub_file.save('%s.epub' % self.slug, ContentFile(epub_file.getvalue()))
             FileRecord(slug=self.slug, type='epub', sha1=sha1(epub_file.getvalue()).hexdigest()).save()
         except NoDublinCore:
             pass
@@ -374,9 +478,19 @@ class Book(models.Model):
             child_book.save()
             book_descendants += list(child_book.children.all())
 
+    def build_txt(self):
+        from StringIO import StringIO
+        from django.core.files.base import ContentFile
+        from librarian import text
+
+        out = StringIO()
+        text.transform(open(self.xml_file.path), out)
+        self.txt_file.save('%s.txt' % self.slug, ContentFile(out.getvalue()))
+        self.save()
+
 
     @classmethod
-    def from_xml_file(cls, xml_file, overwrite=False):
+    def from_xml_file(cls, xml_file, **kwargs):
         # use librarian to parse meta-data
         book_info = dcparser.parse(xml_file)
 
@@ -384,19 +498,32 @@ class Book(models.Model):
             xml_file = File(open(xml_file))
 
         try:
-            return cls.from_text_and_meta(xml_file, book_info, overwrite)
+            return cls.from_text_and_meta(xml_file, book_info, **kwargs)
         finally:
             xml_file.close()
 
     @classmethod
-    def from_text_and_meta(cls, raw_file, book_info, overwrite=False):
+    def from_text_and_meta(cls, raw_file, book_info, overwrite=False, build_epub=True, build_txt=True):
+        import re
         from tempfile import NamedTemporaryFile
-        from slughifi import slughifi
         from markupstring import MarkupString
         from django.core.files.storage import default_storage
 
+        # check for parts before we do anything
+        children = []
+        if hasattr(book_info, 'parts'):
+            for part_url in book_info.parts:
+                base, slug = part_url.rsplit('/', 1)
+                try:
+                    children.append(Book.objects.get(slug=slug))
+                except Book.DoesNotExist, e:
+                    raise Book.DoesNotExist(_('Book with slug = "%s" does not exist.') % slug)
+
+
         # Read book metadata
         book_base, book_slug = book_info.url.rsplit('/', 1)
+        if re.search(r'[^a-zA-Z0-9-]', book_slug):
+            raise ValueError('Invalid characters in slug')
         book, created = Book.objects.get_or_create(slug=book_slug)
 
         if created:
@@ -427,7 +554,7 @@ class Book(models.Model):
                 tag, created = Tag.objects.get_or_create(slug=slughifi(tag_name), category=category)
                 if created:
                     tag.name = tag_name
-                    tag.sort_key = slughifi(tag_sort_key)
+                    tag.sort_key = tag_sort_key.lower()
                     tag.save()
                 book_tags.append(tag)
 
@@ -435,16 +562,10 @@ class Book(models.Model):
 
         book_tag = book.book_tag()
 
-        if hasattr(book_info, 'parts'):
-            for n, part_url in enumerate(book_info.parts):
-                base, slug = part_url.rsplit('/', 1)
-                try:
-                    child_book = Book.objects.get(slug=slug)
-                    child_book.parent = book
-                    child_book.parent_number = n
-                    child_book.save()
-                except Book.DoesNotExist, e:
-                    raise Book.DoesNotExist(_('Book with slug = "%s" does not exist.') % slug)
+        for n, child_book in enumerate(children):
+            child_book.parent = book
+            child_book.parent_number = n
+            child_book.save()
 
         # Save XML and HTML files
         book.xml_file.save('%s.xml' % book.slug, raw_file, save=False)
@@ -477,7 +598,7 @@ class Book(models.Model):
                     tag, created = Tag.objects.get_or_create(slug=slughifi(theme_name), category='theme')
                     if created:
                         tag.name = theme_name
-                        tag.sort_key = slughifi(theme_name)
+                        tag.sort_key = theme_name.lower()
                         tag.save()
                     themes.append(tag)
                 if not themes:
@@ -493,8 +614,11 @@ class Book(models.Model):
                 new_fragment.save()
                 new_fragment.tags = set(book_tags + themes + [book_tag] + ancestor_tags)
 
-        if not book.parent:
-            book.build_epub(remove_descendants=False)
+        if not settings.NO_BUILD_TXT and build_txt:
+            book.build_txt()
+
+        if not settings.NO_BUILD_EPUB and build_epub:
+            book.root_ancestor.build_epub()
 
         book_descendants = list(book.children.all())
         # add l-tag to descendants and their fragments
@@ -502,8 +626,6 @@ class Book(models.Model):
         while len(book_descendants) > 0:
             child_book = book_descendants.pop(0)
             child_book.tags = list(child_book.tags) + [book_tag]
-            if child_book.has_epub_file():
-                child_book.epub_file.delete()
             child_book.save()
             for fragment in child_book.fragments.all():
                 fragment.tags = set(list(fragment.tags) + [book_tag])
@@ -525,12 +647,12 @@ class Book(models.Model):
         for tag in self.tags.exclude(category__in=('book', 'theme', 'set')).order_by():
             tags[tag.pk] = 1
         self.set__tag_counter_value(tags)
-        self.save(reset_short_html=False, refresh_mp3=False)
+        self.save(reset_short_html=False)
         return tags
 
     def reset_tag_counter(self):
         self._tag_counter = None
-        self.save(reset_short_html=False, refresh_mp3=False)
+        self.save(reset_short_html=False)
         if self.parent:
             self.parent.reset_tag_counter()
 
@@ -546,12 +668,12 @@ class Book(models.Model):
             for tag in fragment.tags.filter(category='theme').order_by():
                 tags[tag.pk] = tags.get(tag.pk, 0) + 1
         self.set__theme_counter_value(tags)
-        self.save(reset_short_html=False, refresh_mp3=False)
+        self.save(reset_short_html=False)
         return tags
 
     def reset_theme_counter(self):
         self._theme_counter = None
-        self.save(reset_short_html=False, refresh_mp3=False)
+        self.save(reset_short_html=False)
         if self.parent:
             self.parent.reset_theme_counter()
 
@@ -561,6 +683,22 @@ class Book(models.Model):
             return self.refresh_theme_counter()
         return dict((int(k), v) for k, v in self.get__theme_counter_value().iteritems())
 
+    def pretty_title(self, html_links=False):
+        book = self
+        names = list(book.tags.filter(category='author'))
+
+        books = []
+        while book:
+            books.append(book)
+            book = book.parent
+        names.extend(reversed(books))
+
+        if html_links:
+            names = ['<a href="%s">%s</a>' % (tag.get_absolute_url(), tag.name) for tag in names]
+        else:
+            names = [tag.name for tag in names]
+
+        return ', '.join(names)
 
 
 class Fragment(models.Model):
@@ -594,34 +732,6 @@ class Fragment(models.Model):
             return mark_safe(getattr(self, key))
 
 
-class BookStub(models.Model):
-    title = models.CharField(_('title'), max_length=120)
-    author = models.CharField(_('author'), max_length=120)
-    pd = models.IntegerField(_('goes to public domain'), null=True, blank=True)
-    slug = models.SlugField(_('slug'), max_length=120, unique=True, db_index=True)
-    translator = models.TextField(_('translator'), blank=True)
-    translator_death = models.TextField(_('year of translator\'s death'), blank=True)
-
-    class Meta:
-        ordering = ('title',)
-        verbose_name = _('book stub')
-        verbose_name_plural = _('book stubs')
-
-    def __unicode__(self):
-        return self.title
-
-    @permalink
-    def get_absolute_url(self):
-        return ('catalogue.views.book_detail', [self.slug])
-
-    def in_pd(self):
-        return self.pd is not None and self.pd <= datetime.now().year
-
-    @property
-    def name(self):
-        return self.title
-
-
 class FileRecord(models.Model):
     slug = models.SlugField(_('slug'), max_length=120, db_index=True)
     type = models.CharField(_('type'), max_length=20, db_index=True)
@@ -636,6 +746,12 @@ class FileRecord(models.Model):
     def __unicode__(self):
         return "%s %s.%s" % (self.sha1,  self.slug, self.type)
 
+###########
+#
+# SIGNALS
+#
+###########
+
 
 def _tags_updated_handler(sender, affected_tags, **kwargs):
     # reset tag global counter
@@ -653,3 +769,24 @@ def _tags_updated_handler(sender, affected_tags, **kwargs):
         sender.book.reset_theme_counter()
 tags_updated.connect(_tags_updated_handler)
 
+
+def _m2m_changed_handler(sender, instance, action, reverse, pk_set, **kwargs):
+    """ refresh all the short_html stuff on BookMedia delete """
+    if sender == Book.medias.through and reverse and action == 'pre_clear':
+        for book in instance.book_set.all():
+            book.save()
+m2m_changed.connect(_m2m_changed_handler)
+
+def _pre_delete_handler(sender, instance, **kwargs):
+    """ explicitly clear m2m, so that Books can be refreshed """
+    if sender == BookMedia:
+        instance.book_set.clear()
+pre_delete.connect(_pre_delete_handler)
+
+def _post_save_handler(sender, instance, **kwargs):
+    """ refresh all the short_html stuff on BookMedia update """
+    if sender == BookMedia:
+        for book in instance.book_set.all():
+            book.save()
+post_save.connect(_post_save_handler)
+