I remember asking a similar question 5 years ago :) https://mail-archives.apache.org/mod_mbox/jena-users/201610.mbox/%3cCAE35VmwR+QjzGiEcWwO0sVJcFcnb=CTYqHc-fp7iF550=1b...@mail.gmail.com%3e
ModelFactory.createUnion() might to be an option. https://jena.apache.org/documentation/javadoc/jena/org/apache/jena/rdf/model/ModelFactory.html#createUnion(org.apache.jena.rdf.model.Model,org.apache.jena.rdf.model.Model) On Sat, Aug 28, 2021 at 3:43 PM Andy Seaborne <a...@apache.org> wrote: > > > > On 27/08/2021 12:23, Zak Mc Kracken wrote: > > Hi all, > > > > I have a little RDF file (describing a dataset metadata), which I want > > to read in an helper class and return as a read-only view on the file. > > The reason to return it as read-only is that I also keep a simple cache > > of uri/Object, which is a simplified view of RDF resources in the file, > > so a modifiable Model would make it impossible to keep the two aligned. > > > > That said, I wonder if there is some read-only wrapper for the Jena's > > Model interface, something similar to Collections.unmodifiableXXX(), > > which of course, would be based on the decorator pattern, with > > delegation to a base Model for most of the interface methods, except > > interceptors for addXXX(), which would throw > > UnsupportedOperationException. Would be easy to implement it, but I > > don't like to reinvent wheels, if something like that already exists. > > Apparently there isn't one. Not sure why not. > > There is a read-only graph (and a read-only DatasetGraph) so one way to > create a read-only model is: > > Model model = ModelFactory.createDefaultModel(); > Graph graphRO = new GraphReadOnly(model.getGraph()); > Model modelRO = ModelFactory.createModelForGraph(graphRO); > > Graph is a narrower interface do catching things here is less code. In > fact, GraphBase is read-only unless add/delete(Triple) are overwritten. > > Andy > > > > Thanks, > > Marco. > > > >
