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