RDF prefix not exported in .ttl

[vtoure]

Hi all,

I noticed that RDFlib version 5.0.0 does not export the RDF prefix in the Turtle file (even when explicitly coded with g.bind("rdf", RDF)). It worked with v4.2.2. It is a bug or done on purpose?

[tgbugs]

In 5.0.0 unless a prefix is used in the file (a does not count) then it will not be round tripped. You can specify which/all prefixes to roundtrip via the rountrip_prefixes attribute

rdflib/rdflib/plugins/serializers/turtle.py

Line 45 in c5ff127

roundtrip_prefixes = tuple()

. Here is how it works

rdflib/rdflib/plugins/serializers/turtle.py

Lines 118 to 125 in c5ff127

	if self.roundtrip_prefixes:
	if hasattr(self.roundtrip_prefixes, "__iter__"):
	for prefix, ns in self.store.namespaces():
	if prefix in self.roundtrip_prefixes:
	self.addNamespace(prefix, ns)
	else:
	for prefix, ns in self.store.namespaces():
	self.addNamespace(prefix, ns)

.