Added DCMeta - EAV based application to represent document meta-data. Started to...

[redakcja.git] / apps / dcmeta / models.py

diff --git a/apps/dcmeta/models.py b/apps/dcmeta/models.py
new file mode 100644 (file)
index 0000000..eaa6e86
--- /dev/null
+++ b/apps/dcmeta/models.py
@@ -0,0 +1,85 @@
+from django.db import models
+import eav.models
+import pdb
+
+# Some monkey patches to EAV:
+
+# Allow dots & stuff
+eav.models.slugify = lambda x: x
+
+# Allow more characters 
+eav.models.BaseSchema._meta.get_field_by_name("name")[0].max_length = 200
+
+from django.contrib.auth.models import User
+from django.contrib.contenttypes.generic import GenericRelation, GenericForeignKey
+from django.contrib.contenttypes.models import ContentType
+
+from lxml import etree
+from dcmeta.utils import RDFNS, common_prefixes, NamespaceDescriptor
+import logging
+
+logger = logging.getLogger("django.dcmeta")
+
+class Description(eav.models.BaseEntity):
+    """Collection of meta-data that can be assigned to an entity."""
+    object_id = models.PositiveIntegerField(blank=True, null=True)
+    content_type = models.ForeignKey(ContentType, blank=True, null=True)
+
+    about = GenericForeignKey()
+    about_uri = models.TextField()
+
+    attrs = GenericRelation('Attr', object_id_field="entity_id", content_type_field="entity_type")
+
+    # shortcuts to EAV attributes
+    dublincore = NamespaceDescriptor('http://purl.org/dc/elements/1.1/')
+    marcrel = NamespaceDescriptor('http://www.loc.gov/loc.terms/relators/')
+
+    @classmethod
+    def get_schemata_for_model(self):
+        return Schema.objects.all()
+
+    @classmethod
+    def import_rdf(cls, text):
+        doc = etree.fromstring(text)
+        xml_desc = doc.xpath('/rdf:RDF/rdf:Description', namespaces={"rdf": RDFNS.uri})
+
+        if not xml_desc:
+            raise ValueError("Invalid document structure.")
+
+        xml_desc = xml_desc[0]
+
+        desc = Description.objects.create(about_uri=xml_desc.get(RDFNS("about")))
+
+        for xml_property in xml_desc.iterchildren():
+            property, _created = Schema.objects.get_or_create(
+                                name=xml_property.tag, datatype=Schema.TYPE_TEXT)
+            property.save_attr(desc, xml_property.text)
+
+        desc = Description.objects.get(pk=desc.pk)
+        return desc
+
+    def __getitem__(self, key):
+        if not isinstance(key, tuple):
+            raise ValueError
+        ns, attr = key
+
+        if ns in common_prefixes: # URI given, value stored as prefix
+            ns = common_prefixes[ns]
+
+        return getattr(self, "{%s}%s" % (ns, attr))
+
+    def __setitem__(self, key, value):
+        return setattr(self, "dc_" + key, value)
+
+class Schema(eav.models.BaseSchema):
+    pass
+
+class Choice(eav.models.BaseChoice):
+    """
+        For properties with multiply values.
+    """
+    schema = models.ForeignKey(Schema, related_name='choices')
+
+class Attr(eav.models.BaseAttribute):
+    schema = models.ForeignKey(Schema, related_name='attrs')
+    choice = models.ForeignKey(Choice, blank=True, null=True)