Protect statements from deletion on PUT; delete children on DELETE;

other bug fixes.

lakesuperior/model/ldpr.py

@@ -114,7 +114,8 @@ class Ldpr(metaclass=ABCMeta):
         layout should commit an open transaction. Methods are wrapped in a
         transaction by using the `@transactional` decorator.
 
-        @param uuid (string) UUID of the resource.
+        @param uuid (string) UUID of the resource. If None (must be explicitly
+        set) it refers to the root node.
         '''
         self.uuid = uuid
 
@@ -362,16 +363,12 @@ class Ldpr(metaclass=ABCMeta):
 
         rdfly = cls.load_layout('rdf')
 
-        parent_imr_urn = nsc['fcres'][parent_uuid] if parent_uuid \
-                else rdfly.ROOT_NODE_URN
-        parent_imr = rdfly.extract_imr(parent_imr_urn, minimal=True)
-        if not len(parent_imr.graph):
-            raise ResourceNotExistsError(parent_uuid)
+        parent = cls(parent_uuid, incl_children=False)
 
         # Set prefix.
         if parent_uuid:
             parent_types = { t.identifier for t in \
-                    parent_imr.objects(RDF.type) }
+                    parent.imr.objects(RDF.type) }
             cls._logger.debug('Parent types: {}'.format(
                     parent_types))
             if nsc['ldp'].Container not in parent_types:

lakesuperior/store_layouts/rdf/base_rdf_layout.py

@@ -102,28 +102,17 @@ class BaseRdfLayout(metaclass=ABCMeta):
         return self._store
 
 
-    def rsrc(self, urn):
-        '''
-        Reference to a live data set that can be updated. This exposes the
-        whole underlying triplestore structure and is used to update a
-        resource.
-        '''
-        return self.ds.resource(urn)
-
-
-    def out_rsrc(self, urn):
+    @property
+    def protected_pred(self):
         '''
-        Graph obtained by querying the triplestore and adding any abstraction
-        and filtering to make up a graph that can be used for read-only,
-        API-facing results. Different layouts can implement this in very
-        different ways, so it is an abstract method.
-
-        @return rdflib.resource.Resource
+        Predicated that are not deleted from an existing resources when it is
+        replaced, e.g. by a PUT operation.
         '''
-        imr = self.extract_imr(urn)
-        if not len(imr.graph):
-            raise ResourceNotExistsError
-
+        return {
+            nsc['fcrepo'].created,
+            nsc['fcrepo'].createdBy,
+            nsc['ldp'].contains,
+        }
 
 
     ## PUBLIC METHODS ##
@@ -158,6 +147,29 @@ class BaseRdfLayout(metaclass=ABCMeta):
         return self.ds.query(q, initBindings=initBindings, initNs=nsc)
 
 
+    def rsrc(self, urn):
+        '''
+        Reference to a live data set that can be updated. This exposes the
+        whole underlying triplestore structure and is used to update a
+        resource.
+        '''
+        return self.ds.resource(urn)
+
+
+    def out_rsrc(self, urn):
+        '''
+        Graph obtained by querying the triplestore and adding any abstraction
+        and filtering to make up a graph that can be used for read-only,
+        API-facing results. Different layouts can implement this in very
+        different ways, so it is an abstract method.
+
+        @return rdflib.resource.Resource
+        '''
+        imr = self.extract_imr(urn)
+        if not len(imr.graph):
+            raise ResourceNotExistsError
+
+
     def create_or_replace_rsrc(self, imr):
         '''Create a resource graph in the main graph if it does not exist.
 

lakesuperior/store_layouts/rdf/simple_layout.py

@@ -31,7 +31,7 @@ class SimpleLayout(BaseRdfLayout):
     '''
 
     def extract_imr(self, uri, strict=False, incl_inbound=False,
-                embed_children=False, incl_srv_mgd=True):
+                incl_children=True, embed_children=False, incl_srv_mgd=True):
         '''
         See base_rdf_layout.extract_imr.
         '''
@@ -40,11 +40,14 @@ class SimpleLayout(BaseRdfLayout):
         inbound_qry = '\nOPTIONAL {{ ?s1 ?p1 {} . }} .'.format(uri.n3()) \
                 if incl_inbound else ''
         embed_children_qry = '''
-        OPTIONAL {{
+        \nOPTIONAL {{
           {0} ldp:contains ?c .
           ?c ?cp ?co .
         }}
-        '''.format(uri.n3()) if embed_children else ''
+        '''.format(uri.n3()) if incl_children and embed_children else ''
+
+        incl_children_qry = '\nFILTER ( ?p != ldp:contains )' \
+                if not incl_children else ''
 
         srv_mgd_qry = ''
         if not incl_srv_mgd:
@@ -60,12 +63,12 @@ class SimpleLayout(BaseRdfLayout):
             {uri} ?p ?o .{inb_cnst}
             ?c ?cp ?co .
         }} WHERE {{
-            {uri} ?p ?o .{inb_qry}{embed_chld}{omit_srv_mgd}
+            {uri} ?p ?o .{inb_qry}{incl_chld}{embed_chld}{omit_srv_mgd}
             #FILTER (?p != premis:hasMessageDigest) .
         }}
         '''.format(uri=uri.n3(), inb_cnst=inbound_construct,
-                    inb_qry=inbound_qry, embed_chld=embed_children_qry,
-                    omit_srv_mgd=srv_mgd_qry)
+                    inb_qry=inbound_qry, incl_chld=incl_children_qry,
+                    embed_chld=embed_children_qry, omit_srv_mgd=srv_mgd_qry)
 
         try:
             qres = self.query(q)
@@ -108,20 +111,26 @@ class SimpleLayout(BaseRdfLayout):
         '''
         See base_rdf_layout.replace_rsrc.
         '''
-        # @TODO Move this to LDP.
         rsrc = self.rsrc(imr.identifier)
         # Delete all triples but keep creation date and creator.
-        created = rsrc.value(nsc['fcrepo'].created)
-        created_by = rsrc.value(nsc['fcrepo'].createdBy)
+        #created = rsrc.value(nsc['fcrepo'].created)
+        #created_by = rsrc.value(nsc['fcrepo'].createdBy)
 
-        if not created or not created_by:
-            raise InvalidResourceError(urn)
+        #if not created or not created_by:
+        #    raise InvalidResourceError(urn)
 
-        imr.set(nsc['fcrepo'].created, created)
-        imr.set(nsc['fcrepo'].createdBy, created_by)
+        #imr.set(nsc['fcrepo'].created, created)
+        #imr.set(nsc['fcrepo'].createdBy, created_by)
 
-        # Delete the stored triples.
-        self.delete_rsrc(imr.identifier)
+        # Delete the stored triples but spare the protected predicates.
+        del_trp_qry = []
+        for p in rsrc.predicates():
+            if p.identifier not in self.protected_pred:
+                self._logger.debug('Removing {}'.format(p.identifier))
+                rsrc.remove(p.identifier)
+            else:
+                self._logger.debug('NOT Removing {}'.format(p))
+                imr.remove(p.identifier)
 
         #self.ds |= imr.graph # This does not seem to work with datasets.
         for t in imr.graph:
@@ -136,24 +145,23 @@ class SimpleLayout(BaseRdfLayout):
         '''
         self.ds -= remove_trp
         self.ds += add_trp
-        #for t in remove.predicate_objects():
-        #    self.rsrc.remove(t[0], t[1])
-
-        #for t in add.predicate_objects():
-        #    self.rsrc.add(t[0], t[1])
 
 
-    def delete_rsrc(self, urn, inbound=True):
+    def delete_rsrc(self, urn, inbound=True, delete_children=True):
         '''
         Delete a resource. If `inbound` is specified, delete all inbound
         relationships as well (this is the default).
         '''
         rsrc = self.rsrc(urn)
+        if delete_children:
+            self._logger.info('Deleting resource children')
+            for c in rsrc[nsc['ldp'].contains * '+']:
+                self._logger.debug('Removing child: {}'.format(c))
+                c.remove(Variable('p'))
 
         print('Removing resource {}.'.format(rsrc.identifier))
 
         rsrc.remove(Variable('p'))
-        # @TODO Remove children recursively
         if inbound:
             self.ds.remove(
                     (Variable('s'), Variable('p'), rsrc.identifier))