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