apps/oai/handlers.py

   1 from oaipmh import server, common, metadata, error
   2 from catalogue.models import Book, Tag
   3 from api.models import Deleted
   4 from api.handlers import WL_BASE
   5 from librarian.dcparser import BookInfo
   6 from librarian import WLURI
   7 from django.contrib.contenttypes.models import ContentType
   8 from django.contrib.auth.models import User
   9 from datetime import datetime
  10 from lxml import etree
  11 from lxml.etree import ElementTree
  12 from django.db.models import Q
  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' % 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