apps/catalogue/views.py

   1 # -*- coding: utf-8 -*-
   2 # This file is part of Wolnelektury, licensed under GNU Affero GPLv3 or later.
   3 # Copyright © Fundacja Nowoczesna Polska. See NOTICE for more information.
   4 #
   5 import re
   6 import itertools
   7
   8 from django.conf import settings
   9 from django.core.cache import get_cache
  10 from django.template import RequestContext
  11 from django.template.loader import render_to_string
  12 from django.shortcuts import render_to_response, get_object_or_404, redirect
  13 from django.http import HttpResponse, HttpResponseRedirect, Http404, HttpResponsePermanentRedirect
  14 from django.core.urlresolvers import reverse
  15 from django.db.models import Q
  16 from django.contrib.auth.decorators import login_required, user_passes_test
  17 from django.utils.datastructures import SortedDict
  18 from django.utils.http import urlquote_plus
  19 from django.utils import translation
  20 from django.utils.translation import get_language, ugettext as _, ugettext_lazy
  21 from django.views.decorators.vary import vary_on_headers
  22
  23 from ajaxable.utils import JSONResponse, AjaxableFormView
  24 from catalogue import models
  25 from catalogue import forms
  26 from catalogue.utils import split_tags, MultiQuerySet
  27 from catalogue.templatetags.catalogue_tags import tag_list, collection_list
  28 from pdcounter import models as pdcounter_models
  29 from pdcounter import views as pdcounter_views
  30 from suggest.forms import PublishingSuggestForm
  31 from picture.models import Picture, PictureArea
  32 from picture.views import picture_list_thumb
  33 import logging
  34 staff_required = user_passes_test(lambda user: user.is_staff)
  35 permanent_cache = get_cache('permanent')
  36
  37
  38 @vary_on_headers('X-Requested-With')
  39 def catalogue(request):
  40     cache_key='catalogue.catalogue/' + get_language()
  41     output = permanent_cache.get(cache_key)
  42
  43     if output is None:
  44         tags = models.Tag.objects.exclude(
  45             category__in=('set', 'book')).exclude(book_count=0, picture_count=0)
  46         tags = list(tags)
  47         for tag in tags:
  48             tag.count = tag.book_count + tag.picture_count
  49         categories = split_tags(tags)
  50         fragment_tags = categories.get('theme', [])
  51         collections = models.Collection.objects.all()
  52
  53         render_tag_list = lambda x: render_to_string(
  54             'catalogue/tag_list.html', tag_list(x))
  55         has_pictures = lambda x: filter(lambda y: y.picture_count>0, x)
  56         has_books = lambda x: filter(lambda y: y.book_count>0, x)
  57         def render_split(tags):
  58             with_books = has_books(tags)
  59             with_pictures = has_pictures(tags)
  60             ctx = {}
  61             if with_books:
  62                 ctx['books'] = render_tag_list(with_books)
  63             if with_pictures:
  64                 ctx['pictures'] = render_tag_list(with_pictures)
  65             return render_to_string('catalogue/tag_list_split.html', ctx)
  66
  67         output = {'theme': {}}
  68         output['theme'] = render_split(fragment_tags)
  69         for category, tags in categories.items():
  70             output[category] = render_split(tags)
  71
  72         output['collections'] = render_to_string(
  73             'catalogue/collection_list.html', collection_list(collections))
  74         permanent_cache.set(cache_key, output)
  75     if request.is_ajax():
  76         return JSONResponse(output)
  77     else:
  78         return render_to_response('catalogue/catalogue.html', locals(),
  79             context_instance=RequestContext(request))
  80
  81
  82 def book_list(request, filter=None, get_filter=None,
  83         template_name='catalogue/book_list.html',
  84         nav_template_name='catalogue/snippets/book_list_nav.html',
  85         list_template_name='catalogue/snippets/book_list.html',
  86         cache_key='catalogue.book_list',
  87         context=None,
  88         ):
  89     """ generates a listing of all books, optionally filtered with a test function """
  90     cache_key = "%s/%s" % (cache_key, get_language())
  91     cached = permanent_cache.get(cache_key)
  92     if cached is not None:
  93         rendered_nav, rendered_book_list = cached
  94     else:
  95         if get_filter:
  96             filter = get_filter()
  97         books_by_author, orphans, books_by_parent = models.Book.book_list(filter)
  98         books_nav = SortedDict()
  99         for tag in books_by_author:
 100             if books_by_author[tag]:
 101                 books_nav.setdefault(tag.sort_key[0], []).append(tag)
 102         rendered_nav = render_to_string(nav_template_name, locals())
 103         rendered_book_list = render_to_string(list_template_name, locals())
 104         permanent_cache.set(cache_key, (rendered_nav, rendered_book_list))
 105     return render_to_response(template_name, locals(),
 106         context_instance=RequestContext(request))
 107
 108
 109 def audiobook_list(request):
 110     return book_list(request, Q(media__type='mp3') | Q(media__type='ogg'),
 111                      template_name='catalogue/audiobook_list.html',
 112                      list_template_name='catalogue/snippets/audiobook_list.html',
 113                      cache_key='catalogue.audiobook_list')
 114
 115
 116 def daisy_list(request):
 117     return book_list(request, Q(media__type='daisy'),
 118                      template_name='catalogue/daisy_list.html',
 119                      cache_key='catalogue.daisy_list')
 120
 121
 122 def collection(request, slug):
 123     coll = get_object_or_404(models.Collection, slug=slug)
 124     if coll.kind == 'book':
 125         view = book_list
 126         tmpl = "catalogue/collection.html"
 127     elif coll.kind == 'picture':
 128         view = picture_list_thumb
 129         tmpl = "picture/collection.html"
 130     else:
 131         raise ValueError('How do I show this kind of collection? %s' % coll.kind)
 132     return view(request, get_filter=coll.get_query,
 133                      template_name=tmpl,
 134                      cache_key='catalogue.collection:%s' % coll.slug,
 135                      context={'collection': coll})
 136
 137
 138 def differentiate_tags(request, tags, ambiguous_slugs):
 139     beginning = '/'.join(tag.url_chunk for tag in tags)
 140     unparsed = '/'.join(ambiguous_slugs[1:])
 141     options = []
 142     for tag in models.Tag.objects.exclude(category='book').filter(slug=ambiguous_slugs[0]):
 143         options.append({
 144             'url_args': '/'.join((beginning, tag.url_chunk, unparsed)).strip('/'),
 145             'tags': [tag]
 146         })
 147     return render_to_response('catalogue/differentiate_tags.html',
 148                 {'tags': tags, 'options': options, 'unparsed': ambiguous_slugs[1:]},
 149                 context_instance=RequestContext(request))
 150
 151
 152 # TODO: Rewrite this hellish piece of code which tries to do everything
 153 def tagged_object_list(request, tags='', gallery=True, literature=True):
 154     # preliminary tests and conditions
 155     try:
 156         tags = models.Tag.get_tag_list(tags)
 157     except models.Tag.DoesNotExist:
 158         # Perhaps the user is asking about an author in Public Domain
 159         # counter (they are not represented in tags)
 160         chunks = tags.split('/')
 161         if len(chunks) == 2 and chunks[0] == 'autor':
 162             return pdcounter_views.author_detail(request, chunks[1])
 163         else:
 164             raise Http404
 165     except models.Tag.MultipleObjectsReturned, e:
 166         # Ask the user to disambiguate
 167         return differentiate_tags(request, e.tags, e.ambiguous_slugs)
 168     except models.Tag.UrlDeprecationWarning, e:
 169         return HttpResponsePermanentRedirect(reverse('tagged_object_list', args=['/'.join(tag.url_chunk for tag in e.tags)]))
 170
 171     try:
 172         if len(tags) > settings.MAX_TAG_LIST:
 173             raise Http404
 174     except AttributeError:
 175         pass
 176
 177     if len([tag for tag in tags if tag.category == 'book']):
 178         raise Http404
 179
 180     # beginning of digestion
 181
 182     theme_is_set = [tag for tag in tags if tag.category == 'theme']
 183     shelf_is_set = [tag for tag in tags if tag.category == 'set']
 184     only_shelf = shelf_is_set and len(tags) == 1
 185     only_my_shelf = only_shelf and request.user.is_authenticated() and request.user == tags[0].user
 186
 187
 188     objects = only_author = None
 189     categories = {}
 190     object_queries = []
 191
 192     if theme_is_set:
 193         shelf_tags = [tag for tag in tags if tag.category == 'set']
 194         fragment_tags = [tag for tag in tags if tag.category != 'set']
 195         if literature:
 196             fragments = models.Fragment.tagged.with_all(fragment_tags)
 197         else:
 198             fragments = models.Fragment.objects.none()
 199         if gallery:
 200             areas = PictureArea.tagged.with_all(fragment_tags)
 201         else:
 202             areas = PictureArea.objects.none()
 203
 204         if shelf_tags and literature:
 205             books = models.Book.tagged.with_all(shelf_tags).order_by()
 206             l_tags = models.Tag.objects.filter(category='book',
 207                 slug__in=[book.book_tag_slug() for book in books.iterator()])
 208             fragments = models.Fragment.tagged.with_any(l_tags, fragments)
 209
 210         # newtagging goes crazy if we just try:
 211         #related_tags = models.Tag.objects.usage_for_queryset(fragments, counts=True,
 212         #                    extra={'where': ["catalogue_tag.category != 'book'"]})
 213
 214         related_tags = []
 215
 216         fragment_keys = [fragment.pk for fragment in fragments.iterator()]
 217         if fragment_keys:
 218             related_tags = models.Fragment.tags.usage(counts=True,
 219                                 filters={'pk__in': fragment_keys},
 220                                 extra={'where': ["catalogue_tag.category != 'book'"]})
 221             related_tags = (tag for tag in related_tags if tag not in fragment_tags)
 222             categories = split_tags(related_tags, categories)
 223
 224         object_queries.insert(0, fragments)
 225
 226         area_keys = [area.pk for area in areas.iterator()]
 227         if area_keys:
 228             related_tags = PictureArea.tags.usage(counts=True,
 229                                                          filters={'pk__in': area_keys})
 230             related_tags = (tag for tag in related_tags if tag not in fragment_tags)
 231
 232             categories = split_tags(related_tags, categories)
 233         object_queries.append(areas)
 234         objects = MultiQuerySet(*object_queries)
 235     else:
 236         if literature:
 237             if shelf_is_set:
 238                 books = models.Book.tagged.with_all(tags)
 239             else:
 240                 books = models.Book.tagged_top_level(tags)
 241         else:
 242             books = models.Book.objects.none()
 243
 244         if gallery:
 245             pictures = Picture.tagged.with_all(tags)
 246         else:
 247             pictures = Picture.objects.none()
 248
 249         if literature and books.count() > 0:
 250             # get related tags from `tag_counter` and `theme_counter`
 251             related_counts = {}
 252             tags_pks = [tag.pk for tag in tags]
 253             for book in books:
 254                 for tag_pk, value in itertools.chain(book.tag_counter.iteritems(), book.theme_counter.iteritems()):
 255                     if tag_pk in tags_pks:
 256                         continue
 257                     related_counts[tag_pk] = related_counts.get(tag_pk, 0) + value
 258             related_tags = models.Tag.objects.filter(pk__in=related_counts.keys())
 259             related_tags = [tag for tag in related_tags if tag not in tags]
 260             for tag in related_tags:
 261                 tag.count = related_counts[tag.pk]
 262
 263             categories = split_tags(related_tags)
 264             del related_tags
 265
 266         objects = MultiQuerySet(pictures, books)
 267
 268     if not objects:
 269         only_author = len(tags) == 1 and tags[0].category == 'author'
 270         objects = models.Book.objects.none()
 271
 272
 273     return render_to_response('catalogue/tagged_object_list.html',
 274         {
 275             'object_list': objects,
 276             'categories': categories,
 277             'only_shelf': only_shelf,
 278             'only_author': only_author,
 279             'only_my_shelf': only_my_shelf,
 280             'formats_form': forms.DownloadFormatsForm(),
 281             'tags': tags,
 282             'theme_is_set': theme_is_set,
 283         },
 284         context_instance=RequestContext(request))
 285
 286
 287 def book_fragments(request, slug, theme_slug):
 288     book = get_object_or_404(models.Book, slug=slug)
 289
 290     book_tag = book.book_tag()
 291     theme = get_object_or_404(models.Tag, slug=theme_slug, category='theme')
 292     fragments = models.Fragment.tagged.with_all([book_tag, theme])
 293
 294     return render_to_response('catalogue/book_fragments.html', locals(),
 295         context_instance=RequestContext(request))
 296
 297
 298 def book_detail(request, slug):
 299     try:
 300         book = models.Book.objects.get(slug=slug)
 301     except models.Book.DoesNotExist:
 302         return pdcounter_views.book_stub_detail(request, slug)
 303
 304     book_children = book.children.all().order_by('parent_number', 'sort_key')
 305     return render_to_response('catalogue/book_detail.html', locals(),
 306         context_instance=RequestContext(request))
 307
 308
 309 def player(request, slug):
 310     book = get_object_or_404(models.Book, slug=slug)
 311     if not book.has_media('mp3'):
 312         raise Http404
 313
 314     ogg_files = {}
 315     for m in book.media.filter(type='ogg').order_by().iterator():
 316         ogg_files[m.name] = m
 317
 318     audiobooks = []
 319     have_oggs = True
 320     projects = set()
 321     for mp3 in book.media.filter(type='mp3').iterator():
 322         # ogg files are always from the same project
 323         meta = mp3.extra_info
 324         project = meta.get('project')
 325         if not project:
 326             # temporary fallback
 327             project = u'CzytamySłuchając'
 328
 329         projects.add((project, meta.get('funded_by', '')))
 330
 331         media = {'mp3': mp3}
 332
 333         ogg = ogg_files.get(mp3.name)
 334         if ogg:
 335             media['ogg'] = ogg
 336         else:
 337             have_oggs = False
 338         audiobooks.append(media)
 339
 340     projects = sorted(projects)
 341
 342     extra_info = book.extra_info
 343
 344     return render_to_response('catalogue/player.html', locals(),
 345         context_instance=RequestContext(request))
 346
 347
 348 def book_text(request, slug):
 349     book = get_object_or_404(models.Book, slug=slug)
 350
 351     if not book.has_html_file():
 352         raise Http404
 353     related = book.related_info()
 354     return render_to_response('catalogue/book_text.html', locals(),
 355         context_instance=RequestContext(request))
 356
 357
 358 # ==========
 359 # = Search =
 360 # ==========
 361
 362 def _no_diacritics_regexp(query):
 363     """ returns a regexp for searching for a query without diacritics
 364
 365     should be locale-aware """
 366     names = {
 367         u'a':u'aąĄ', u'c':u'cćĆ', u'e':u'eęĘ', u'l': u'lłŁ', u'n':u'nńŃ', u'o':u'oóÓ', u's':u'sśŚ', u'z':u'zźżŹŻ',
 368         u'ą':u'ąĄ', u'ć':u'ćĆ', u'ę':u'ęĘ', u'ł': u'łŁ', u'ń':u'ńŃ', u'ó':u'óÓ', u'ś':u'śŚ', u'ź':u'źŹ', u'ż':u'żŻ'
 369         }
 370     def repl(m):
 371         l = m.group()
 372         return u"(%s)" % '|'.join(names[l])
 373     return re.sub(u'[%s]' % (u''.join(names.keys())), repl, query)
 374
 375 def unicode_re_escape(query):
 376     """ Unicode-friendly version of re.escape """
 377     return re.sub('(?u)(\W)', r'\\\1', query)
 378
 379 def _word_starts_with(name, prefix):
 380     """returns a Q object getting models having `name` contain a word
 381     starting with `prefix`
 382
 383     We define word characters as alphanumeric and underscore, like in JS.
 384
 385     Works for MySQL, PostgreSQL, Oracle.
 386     For SQLite, _sqlite* version is substituted for this.
 387     """
 388     kwargs = {}
 389
 390     prefix = _no_diacritics_regexp(unicode_re_escape(prefix))
 391     # can't use [[:<:]] (word start),
 392     # but we want both `xy` and `(xy` to catch `(xyz)`
 393     kwargs['%s__iregex' % name] = u"(^|[^[:alnum:]_])%s" % prefix
 394
 395     return Q(**kwargs)
 396
 397
 398 def _word_starts_with_regexp(prefix):
 399     prefix = _no_diacritics_regexp(unicode_re_escape(prefix))
 400     return ur"(^|(?<=[^\wąćęłńóśźżĄĆĘŁŃÓŚŹŻ]))%s" % prefix
 401
 402
 403 def _sqlite_word_starts_with(name, prefix):
 404     """ version of _word_starts_with for SQLite
 405
 406     SQLite in Django uses Python re module
 407     """
 408     kwargs = {}
 409     kwargs['%s__iregex' % name] = _word_starts_with_regexp(prefix)
 410     return Q(**kwargs)
 411
 412
 413 if hasattr(settings, 'DATABASES'):
 414     if settings.DATABASES['default']['ENGINE'] == 'django.db.backends.sqlite3':
 415         _word_starts_with = _sqlite_word_starts_with
 416 elif settings.DATABASE_ENGINE == 'sqlite3':
 417     _word_starts_with = _sqlite_word_starts_with
 418
 419
 420 class App():
 421     def __init__(self, name, view):
 422         self.name = name
 423         self._view = view
 424         self.lower = name.lower()
 425         self.category = 'application'
 426     def view(self):
 427         return reverse(*self._view)
 428
 429 _apps = (
 430     App(u'Leśmianator', (u'lesmianator', )),
 431     )
 432
 433
 434 def _tags_starting_with(prefix, user=None):
 435     prefix = prefix.lower()
 436     # PD counter
 437     book_stubs = pdcounter_models.BookStub.objects.filter(_word_starts_with('title', prefix))
 438     authors = pdcounter_models.Author.objects.filter(_word_starts_with('name', prefix))
 439
 440     books = models.Book.objects.filter(_word_starts_with('title', prefix))
 441     tags = models.Tag.objects.filter(_word_starts_with('name', prefix))
 442     if user and user.is_authenticated():
 443         tags = tags.filter(~Q(category='book') & (~Q(category='set') | Q(user=user)))
 444     else:
 445         tags = tags.filter(~Q(category='book') & ~Q(category='set'))
 446
 447     prefix_regexp = re.compile(_word_starts_with_regexp(prefix))
 448     return list(books) + list(tags) + [app for app in _apps if prefix_regexp.search(app.lower)] + list(book_stubs) + list(authors)
 449
 450
 451 def _get_result_link(match, tag_list):
 452     if isinstance(match, models.Tag):
 453         return reverse('catalogue.views.tagged_object_list',
 454             kwargs={'tags': '/'.join(tag.url_chunk for tag in tag_list + [match])}
 455         )
 456     elif isinstance(match, App):
 457         return match.view()
 458     else:
 459         return match.get_absolute_url()
 460
 461
 462 def _get_result_type(match):
 463     if isinstance(match, models.Book) or isinstance(match, pdcounter_models.BookStub):
 464         type = 'book'
 465     else:
 466         type = match.category
 467     return type
 468
 469
 470 def books_starting_with(prefix):
 471     prefix = prefix.lower()
 472     return models.Book.objects.filter(_word_starts_with('title', prefix))
 473
 474
 475 def find_best_matches(query, user=None):
 476     """ Finds a models.Book, Tag, models.BookStub or Author best matching a query.
 477
 478     Returns a with:
 479       - zero elements when nothing is found,
 480       - one element when a best result is found,
 481       - more then one element on multiple exact matches
 482
 483     Raises a ValueError on too short a query.
 484     """
 485
 486     query = query.lower()
 487     if len(query) < 2:
 488         raise ValueError("query must have at least two characters")
 489
 490     result = tuple(_tags_starting_with(query, user))
 491     # remove pdcounter stuff
 492     book_titles = set(match.pretty_title().lower() for match in result
 493                       if isinstance(match, models.Book))
 494     authors = set(match.name.lower() for match in result
 495                   if isinstance(match, models.Tag) and match.category=='author')
 496     result = tuple(res for res in result if not (
 497                  (isinstance(res, pdcounter_models.BookStub) and res.pretty_title().lower() in book_titles)
 498                  or (isinstance(res, pdcounter_models.Author) and res.name.lower() in authors)
 499              ))
 500
 501     exact_matches = tuple(res for res in result if res.name.lower() == query)
 502     if exact_matches:
 503         return exact_matches
 504     else:
 505         return tuple(result)[:1]
 506
 507
 508 def search(request):
 509     tags = request.GET.get('tags', '')
 510     prefix = request.GET.get('q', '')
 511
 512     try:
 513         tag_list = models.Tag.get_tag_list(tags)
 514     except:
 515         tag_list = []
 516
 517     try:
 518         result = find_best_matches(prefix, request.user)
 519     except ValueError:
 520         return render_to_response('catalogue/search_too_short.html', {'tags':tag_list, 'prefix':prefix},
 521             context_instance=RequestContext(request))
 522
 523     if len(result) == 1:
 524         return HttpResponseRedirect(_get_result_link(result[0], tag_list))
 525     elif len(result) > 1:
 526         return render_to_response('catalogue/search_multiple_hits.html',
 527             {'tags':tag_list, 'prefix':prefix, 'results':((x, _get_result_link(x, tag_list), _get_result_type(x)) for x in result)},
 528             context_instance=RequestContext(request))
 529     else:
 530         form = PublishingSuggestForm(initial={"books": prefix + ", "})
 531         return render_to_response('catalogue/search_no_hits.html',
 532             {'tags':tag_list, 'prefix':prefix, "pubsuggest_form": form},
 533             context_instance=RequestContext(request))
 534
 535
 536 def tags_starting_with(request):
 537     prefix = request.GET.get('q', '')
 538     # Prefix must have at least 2 characters
 539     if len(prefix) < 2:
 540         return HttpResponse('')
 541     tags_list = []
 542     result = ""
 543     for tag in _tags_starting_with(prefix, request.user):
 544         if not tag.name in tags_list:
 545             result += "\n" + tag.name
 546             tags_list.append(tag.name)
 547     return HttpResponse(result)
 548
 549 def json_tags_starting_with(request, callback=None):
 550     # Callback for JSONP
 551     prefix = request.GET.get('q', '')
 552     callback = request.GET.get('callback', '')
 553     # Prefix must have at least 2 characters
 554     if len(prefix) < 2:
 555         return HttpResponse('')
 556     tags_list = []
 557     for tag in _tags_starting_with(prefix, request.user):
 558         if not tag.name in tags_list:
 559             tags_list.append(tag.name)
 560     if request.GET.get('mozhint', ''):
 561         result = [prefix, tags_list]
 562     else:
 563         result = {"matches": tags_list}
 564     return JSONResponse(result, callback)
 565
 566
 567 # =========
 568 # = Admin =
 569 # =========
 570 @login_required
 571 @staff_required
 572 def import_book(request):
 573     """docstring for import_book"""
 574     book_import_form = forms.BookImportForm(request.POST, request.FILES)
 575     if book_import_form.is_valid():
 576         try:
 577             book_import_form.save()
 578         except:
 579             import sys
 580             import pprint
 581             import traceback
 582             info = sys.exc_info()
 583             exception = pprint.pformat(info[1])
 584             tb = '\n'.join(traceback.format_tb(info[2]))
 585             return HttpResponse(_("An error occurred: %(exception)s\n\n%(tb)s") % {'exception':exception, 'tb':tb}, mimetype='text/plain')
 586         return HttpResponse(_("Book imported successfully"))
 587     else:
 588         return HttpResponse(_("Error importing file: %r") % book_import_form.errors)
 589
 590
 591 # info views for API
 592
 593 def book_info(request, id, lang='pl'):
 594     book = get_object_or_404(models.Book, id=id)
 595     # set language by hand
 596     translation.activate(lang)
 597     return render_to_response('catalogue/book_info.html', locals(),
 598         context_instance=RequestContext(request))
 599
 600
 601 def tag_info(request, id):
 602     tag = get_object_or_404(models.Tag, id=id)
 603     return HttpResponse(tag.description)
 604
 605
 606 def download_zip(request, format, slug=None):
 607     url = None
 608     if format in models.Book.ebook_formats:
 609         url = models.Book.zip_format(format)
 610     elif format in ('mp3', 'ogg') and slug is not None:
 611         book = get_object_or_404(models.Book, slug=slug)
 612         url = book.zip_audiobooks(format)
 613     else:
 614         raise Http404('No format specified for zip package')
 615     return HttpResponseRedirect(urlquote_plus(settings.MEDIA_URL + url, safe='/?='))
 616
 617
 618 class CustomPDFFormView(AjaxableFormView):
 619     form_class = forms.CustomPDFForm
 620     title = ugettext_lazy('Download custom PDF')
 621     submit = ugettext_lazy('Download')
 622     honeypot = True
 623
 624     def __call__(self, *args, **kwargs):
 625         if settings.NO_CUSTOM_PDF:
 626             raise Http404('Custom PDF is disabled')
 627         return super(CustomPDFFormView, self).__call__(*args, **kwargs)
 628
 629     def form_args(self, request, obj):
 630         """Override to parse view args and give additional args to the form."""
 631         return (obj,), {}
 632
 633     def get_object(self, request, slug, *args, **kwargs):
 634         return get_object_or_404(models.Book, slug=slug)
 635
 636     def context_description(self, request, obj):
 637         return obj.pretty_title()