apps/oai/handlers.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 from oaipmh import server, common, metadata, error
   6 from catalogue.models import Book, Tag
   7 from api.models import Deleted
   8 from api.handlers import WL_BASE
   9 from librarian import WLURI
  10 from django.contrib.contenttypes.models import ContentType
  11 from datetime import datetime
  12 from lxml import etree
  13 from django.conf import settings
  14 from django.contrib.sites.models import Site
  15 from django.utils import timezone
  16
  17
  18 make_time_naive = lambda d: timezone.localtime(d).replace(tzinfo=None)
  19
  20 WL_DC_READER_XPATH = '(.|*)/rdf:RDF/rdf:Description/%s/text()'
  21 wl_dc_reader = metadata.MetadataReader(
  22     fields={
  23     'title':       ('textList', WL_DC_READER_XPATH % 'dc:title'),
  24     'creator':     ('textList', WL_DC_READER_XPATH % 'dc:creator'),
  25     'subject':     ('textList', (WL_DC_READER_XPATH + ' | ' + WL_DC_READER_XPATH + ' | ' + WL_DC_READER_XPATH) %
  26                     ('dc:subject.period', 'dc:subject.type', 'dc:subject.genre')),
  27     'description': ('textList', WL_DC_READER_XPATH % 'dc:description'),
  28     'publisher':   ('textList', WL_DC_READER_XPATH % 'dc:publisher'),
  29     'contributor': ('textList', (WL_DC_READER_XPATH + ' | ' + WL_DC_READER_XPATH + ' | ' + WL_DC_READER_XPATH) %
  30                     ('dc:contributor.editor', 'dc:contributor.translator', 'dc:contributor.technical_editor')),
  31     'date':        ('textList', WL_DC_READER_XPATH % 'dc:date'),
  32     'type':        ('textList', WL_DC_READER_XPATH % 'dc:type'),
  33     'format':      ('textList', WL_DC_READER_XPATH % 'dc:format'),
  34     'identifier':  ('textList', WL_DC_READER_XPATH % 'dc:identifier.url'),
  35     'source':      ('textList', WL_DC_READER_XPATH % 'dc:source'),
  36     'language':    ('textList', WL_DC_READER_XPATH % 'dc:language'),
  37     #'isPartOf':     ('textList', 'rdf:RDF/rdf:Description/dc:relation.isPartOf/text()'),
  38     'hasPart':     ('textList', WL_DC_READER_XPATH % 'dc:relation.hasPart'),
  39     #    'relation':    ('textList', 'rdf:RDF/rdf:Description/dc:relation/text()'),
  40     #    'coverage':    ('textList', 'rdf:RDF/rdf:Description/dc:coverage/text()'),
  41     'rights':      ('textList', WL_DC_READER_XPATH % 'dc:rights')
  42     },
  43     namespaces={
  44     'dc': 'http://purl.org/dc/elements/1.1/',
  45     'rdf': 'http://www.w3.org/1999/02/22-rdf-syntax-ns#'}
  46     )
  47
  48
  49 NS_DCTERMS = "http://purl.org/dc/terms/"
  50
  51
  52 def nsdcterms(name):
  53     return '{%s}%s' % (NS_DCTERMS, name)
  54
  55
  56 class Catalogue(common.ResumptionOAIPMH):
  57     TAG_CATEGORIES = ['author', 'epoch', 'kind', 'genre']
  58
  59     def __init__(self, metadata_registry):
  60         super(Catalogue, self).__init__()
  61         self.metadata_registry = metadata_registry
  62
  63         self.oai_id = "oai:" + Site.objects.get_current().domain + ":%s"
  64
  65         # earliest change
  66         year_zero = timezone.make_aware(datetime(1990, 1, 1, 0, 0, 0), timezone.utc)
  67
  68         try:
  69             earliest_change = \
  70                 Book.objects.order_by('changed_at')[0].changed_at
  71         except: earliest_change = year_zero
  72
  73         try:
  74             earliest_delete = \
  75                 Deleted.objects.exclude(slug__exact=u'').ordery_by('deleted_at')[0].deleted_at
  76         except: earliest_delete = year_zero
  77
  78         self.earliest_datestamp = earliest_change <= earliest_delete and \
  79             earliest_change or earliest_delete
  80
  81     def metadata(self, book):
  82         try:
  83             xml = etree.parse(book.xml_file)
  84         finally:
  85             book.xml_file.close()
  86         md = wl_dc_reader(xml)
  87         m = md.getMap()
  88         if book.parent:
  89             m['isPartOf'] = [str(WLURI.from_slug(book.parent.slug))]
  90         return m
  91
  92     def record_for_book(self, book, headers_only=False):
  93         meta = None
  94         identifier = self.slug_to_identifier(book.slug)
  95         if isinstance(book, Book):
  96             #            setSpec = map(self.tag_to_setspec, book.tags.filter(category__in=self.TAG_CATEGORIES))
  97             header = common.Header(identifier, make_time_naive(book.changed_at), [], False)
  98             if not headers_only:
  99                 meta = common.Metadata(self.metadata(book))
 100             about = None
 101         elif isinstance(book, Deleted):
 102             header = common.Header(identifier, make_time_naive(book.deleted_at), [], True)
 103             if not headers_only:
 104                 meta = common.Metadata({})
 105             about = None
 106         if headers_only:
 107             return header
 108         return header, meta, about
 109
 110     def identify(self, **kw):
 111         ident = common.Identify(
 112             'Wolne Lektury',  # generate
 113             '%s/oaipmh' % unicode(WL_BASE),  # generate
 114             '2.0',  # version
 115             [m[1] for m in settings.MANAGERS],  # adminEmails
 116             make_time_naive(self.earliest_datestamp),  # earliest datestamp of any change
 117             'persistent',  # deletedRecord
 118             'YYYY-MM-DDThh:mm:ssZ',  # granularity
 119             ['identity'],  # compression
 120             []  # descriptions
 121             )
 122         return ident
 123
 124     def books(self, tag, from_, until):
 125         if tag:
 126             # we do not support sets, since they are problematic for deleted books.
 127             raise error.NoSetHierarchyError("Wolne Lektury does not support sets.")
 128             # books = Book.tagged.with_all([tag])
 129         else:
 130             books = Book.objects.all()
 131         deleted = Deleted.objects.exclude(slug__exact=u'')
 132
 133         books = books.order_by('changed_at')
 134         deleted = deleted.order_by('deleted_at')
 135         if from_:
 136             books = books.filter(changed_at__gte=from_)
 137             deleted = deleted.filter(deleted_at__gte=from_)
 138         if until:
 139             books = books.filter(changed_at__lte=until)
 140             deleted = deleted.filter(deleted_at__lte=until)
 141         return list(books) + list(deleted)
 142
 143     @staticmethod
 144     def tag_to_setspec(tag):
 145         return "%s:%s" % (tag.category, tag.slug)
 146
 147     @staticmethod
 148     def setspec_to_tag(s):
 149         if not s: return None
 150         cs = s.split(':')
 151         if len(cs) == 2:
 152             if not cs[0] in Catalogue.TAG_CATEGORIES:
 153                 raise error.NoSetHierarchyError("No category part in set")
 154             tag = Tag.objects.get(slug=cs[1], category=cs[0])
 155             return tag
 156         raise error.NoSetHierarchyError("Setspec should have two components: category:slug")
 157
 158     def getRecord(self, **kw):
 159         """
 160 Returns (header, metadata, about) for given record.
 161         """
 162         slug = self.identifier_to_slug(kw['identifier'])
 163         try:
 164             book = Book.objects.get(slug=slug)
 165             return self.record_for_book(book)
 166         except Book.DoesNotExist:
 167             book_type = ContentType.objects.get_for_model(Book)
 168             try:
 169                 deleted_book = Deleted.objects.get(content_type=book_type,
 170                                                   slug=slug)
 171             except:
 172                 raise error.IdDoesNotExistError("No item for this identifier")
 173             return self.record_for_book(deleted_book)
 174
 175     def validate_kw(self, kw):
 176         if 'resumptionToken' in kw:
 177             raise error.BadResumptionTokenError("No resumption token support at this point")
 178         if 'metadataPrefix' in kw and not self.metadata_registry.hasWriter(kw['metadataPrefix']):
 179             raise error.CannotDisseminateFormatError("This format is not supported")
 180
 181     def identifier_to_slug(self, ident):
 182         return ident.split(':')[-1]
 183
 184     def slug_to_identifier(self, slug):
 185         return self.oai_id % slug
 186
 187     def listIdentifiers(self, **kw):
 188         self.validate_kw(kw)
 189         records = [self.record_for_book(book, headers_only=True) for
 190                    book in self.books(None,
 191                            kw.get('from_', None),
 192                            kw.get('until', None))]
 193         return records, None
 194
 195     def listRecords(self, **kw):
 196         """
 197 can get a resumptionToken kw.
 198 returns result, token
 199         """
 200         self.validate_kw(kw)
 201         records = [self.record_for_book(book) for
 202                    book in self.books(None,
 203                            kw.get('from_', None),
 204                            kw.get('until', None))]
 205
 206         return records, None
 207
 208     def listMetadataFormats(self, **kw):
 209         formats = [
 210             ('oai_dc',
 211              'http://www.openarchives.org/OAI/2.0/oai_dc.xsd',
 212              server.NS_OAIDC),
 213             ('qdc',
 214              'http://dublincore.org/schemas/xmls/qdc/2006/01/06/dcterms.xsd',
 215              NS_DCTERMS)]
 216         if 'identifier' in kw:
 217             slug = self.identifier_to_slug(kw['identifier'])
 218             try:
 219                 b = Book.objects.get(slug=slug)
 220                 return formats
 221             except:
 222                 try:
 223                     d = Deleted.objects.get(slug=slug)
 224                     return []
 225                 except:
 226                     raise error.IdDoesNotExistError("This id does not exist")
 227         else:
 228             return formats
 229
 230     def listSets(self, **kw):
 231         raise error.NoSetHierarchyError("Wolne Lektury does not support sets.")
 232         # tags = []
 233         # for category in Catalogue.TAG_CATEGORIES:
 234         #     for tag in Tag.objects.filter(category=category):
 235         #         tags.append(("%s:%s" % (tag.category, tag.slug),
 236         #                      tag.name,
 237         #                      tag.description))
 238         # return tags, None