inverted precedence of base: graph wins over adding base to serialize(). Added RDF/XML, TriX & 1/2 TriG (incomplete)issue_1003

5 files changed, 37 insertions, 16 deletions

diff --git a/rdflib/graph.py b/rdflib/graph.py
index a00730ce..9868b097 100644
--- a/rdflib/graph.py
+++ b/rdflib/graph.py
@@ -954,18 +954,20 @@ class Graph(Node):
         but "xml", "n3", "turtle", "nt", "pretty-xml", "trix", "trig" and "nquads" are built in.
         """
 
-        # if a base is set here, use it, else if it was set at graph creation time, use that (self.base)
-        if base is not None:
-            self.base = base
+        # if base is set for the graph use that, if not and a base is given here, use that
+        if self.base is not None:
+            base = self.base
+        else:
+            pass  # i.e. base is set in this method
 
         serializer = plugin.get(format, Serializer)(self)
         if destination is None:
             stream = BytesIO()
-            serializer.serialize(stream, base=self.base, encoding=encoding, **args)
+            serializer.serialize(stream, base=base, encoding=encoding, **args)
             return stream.getvalue()
         if hasattr(destination, "write"):
             stream = destination
-            serializer.serialize(stream, base=self.base, encoding=encoding, **args)
+            serializer.serialize(stream, base=base, encoding=encoding, **args)
         else:
             location = destination
             scheme, netloc, path, params, _query, fragment = urlparse(location)
@@ -976,7 +978,7 @@ class Graph(Node):
                 return
             fd, name = tempfile.mkstemp()
             stream = os.fdopen(fd, "wb")
-            serializer.serialize(stream, base=self.base, encoding=encoding, **args)
+            serializer.serialize(stream, base=base, encoding=encoding, **args)
             stream.close()
             if hasattr(shutil, "move"):
                 shutil.move(name, path)
@@ -1657,13 +1659,13 @@ class Dataset(ConjunctiveGraph):
     .. versionadded:: 4.0
     """
 
-    def __init__(self, store="default", default_union=False):
+    def __init__(self, store="default", default_union=False, default_graph_base=None):
         super(Dataset, self).__init__(store=store, identifier=None)
 
         if not self.store.graph_aware:
             raise Exception("DataSet must be backed by a graph-aware store!")
         self.default_context = Graph(
-            store=self.store, identifier=DATASET_DEFAULT_GRAPH_ID
+            store=self.store, identifier=DATASET_DEFAULT_GRAPH_ID, base=default_graph_base
         )
 
         self.default_union = default_union
@@ -1674,7 +1676,7 @@ class Dataset(ConjunctiveGraph):
         )
         return pattern % self.store.__class__.__name__
 
-    def graph(self, identifier=None):
+    def graph(self, identifier=None, base=None):
         if identifier is None:
             from rdflib.term import rdflib_skolem_genid
 
@@ -1684,6 +1686,7 @@ class Dataset(ConjunctiveGraph):
             identifier = BNode().skolemize()
 
         g = self._graph(identifier)
+        g.base = base
 
         self.store.add_graph(g)
         return g
diff --git a/rdflib/plugins/serializers/rdfxml.py b/rdflib/plugins/serializers/rdfxml.py
index 631c8fe0..0da1cccd 100644
--- a/rdflib/plugins/serializers/rdfxml.py
+++ b/rdflib/plugins/serializers/rdfxml.py
@@ -46,7 +46,11 @@ class XMLSerializer(Serializer):
             yield prefix, namespace
 
     def serialize(self, stream, base=None, encoding=None, **args):
-        self.base = base
+        # if base is set for the graph use that, if not and a base is given here, use that
+        if self.store.base is not None:
+            self.base = self.store.base
+        else:
+            self.base = base
         self.__stream = stream
         self.__serialized = {}
         encoding = self.encoding
@@ -60,8 +64,8 @@ class XMLSerializer(Serializer):
         write('<rdf:RDF\n')
 
         # If provided, write xml:base attribute for the RDF
-        if "xml_base" in args:
-            write('   xml:base="%s"\n' % args['xml_base'])
+        if self.base:
+            write('   xml:base="%s"\n' % self.base)
         # TODO:
         # assert(
         #    namespaces["http://www.w3.org/1999/02/22-rdf-syntax-ns#"]=='rdf')
diff --git a/rdflib/plugins/serializers/trig.py b/rdflib/plugins/serializers/trig.py
index 6c05ad75..2cfc2145 100644
--- a/rdflib/plugins/serializers/trig.py
+++ b/rdflib/plugins/serializers/trig.py
@@ -39,7 +39,7 @@ class TrigSerializer(TurtleSerializer):
             for triple in context:
                 self.preprocessTriple(triple)
 
-            self._contexts[context]=(self.orderSubjects(), self._subjects, self._references)
+            self._contexts[context] = (self.orderSubjects(), self._subjects, self._references)
 
     def reset(self):
         super(TrigSerializer, self).reset()
@@ -49,7 +49,11 @@ class TrigSerializer(TurtleSerializer):
                   spacious=None, **args):
         self.reset()
         self.stream = stream
-        self.base = base
+        # if base is set for the graph use that, if not and a base is given here, use that
+        if self.store.base is not None:
+            self.base = self.store.base
+        else:
+            self.base = base
 
         if spacious is not None:
             self._spacious = spacious
diff --git a/rdflib/plugins/serializers/trix.py b/rdflib/plugins/serializers/trix.py
index fceec6bd..f3477eab 100644
--- a/rdflib/plugins/serializers/trix.py
+++ b/rdflib/plugins/serializers/trix.py
@@ -29,6 +29,10 @@ class TriXSerializer(Serializer):
         self.writer = XMLWriter(stream, nm, encoding, extra_ns={"": TRIXNS})
 
         self.writer.push(TRIXNS[u"TriX"])
+        if self.store.base:
+            base = self.store.base
+        if base is not None:
+            self.writer.attribute("http://www.w3.org/XML/1998/namespacebase", base)
         self.writer.namespaces()
 
         if isinstance(self.store, ConjunctiveGraph):
@@ -44,6 +48,8 @@ class TriXSerializer(Serializer):
 
     def _writeGraph(self, graph):
         self.writer.push(TRIXNS[u"graph"])
+        if graph.base:
+            self.writer.attribute("http://www.w3.org/XML/1998/namespacebase", graph.base)
         if isinstance(graph.identifier, URIRef):
             self.writer.element(
                 TRIXNS[u"uri"], content=text_type(graph.identifier))
diff --git a/rdflib/plugins/serializers/turtle.py b/rdflib/plugins/serializers/turtle.py
index 63f9da06..b7f50087 100644
--- a/rdflib/plugins/serializers/turtle.py
+++ b/rdflib/plugins/serializers/turtle.py
@@ -224,8 +224,10 @@ class TurtleSerializer(RecursiveSerializer):
                   spacious=None, **args):
         self.reset()
         self.stream = stream
-        # if base is set here, override previously set base if set at graph init
-        if base is not None:
+        # if base is set for the graph use that, if not and a base is given here, use that
+        if self.store.base is not None:
+            self.base = self.store.base
+        else:
             self.base = base
 
         if spacious is not None:
@@ -248,6 +250,8 @@ class TurtleSerializer(RecursiveSerializer):
         self.endDocument()
         stream.write(b("\n"))
 
+        self.base = None
+
     def preprocessTriple(self, triple):
         super(TurtleSerializer, self).preprocessTriple(triple)
         for i, node in enumerate(triple):