fcr:content URI to force non-RDF content download.

doc/notes/fcrepo4_deltas.md

@@ -167,13 +167,22 @@ specs should not notice any difference.
 The following are improvements in performance or usability that can only be taken
 advantage of if client code is adjusted.
 
-### LDP-NR metadata by content negotiation
+### LDP-NR content and metadata
 
 FCREPO4 relies on the `/fcr:metadata` identifier to retrieve RDF metadata about
 an LDP-NR. LAKEsuperior supports this as a legacy option, but encourages the
-use of content negotiation to do the same. Any request to an LDP-NR with an
-`Accept` header set to one of the supported RDF serialization formats will
-yield the RDF metadata of the resource instead of the binary contents.
+use of content negotiation to do the same while offering explicit endpoints
+for RDF and non-RDF content retrieval.
+
+Any request to an LDP-NR with an `Accept` header set to one of the supported
+RDF serialization formats will yield the RDF metadata of the resource instead
+of the binary contents.
+
+The `fcr:metadata` URI returns the RDF metadata of a LDP-NR.
+
+The `fcr:content` URI returns the non-RDF content.
+
+The two optionsabove return an HTTP error if requested for a LDP-RS.
 
 ### "Include" and "Omit" options for children
 

lakesuperior/endpoints/ldp.py

@@ -107,9 +107,11 @@ def log_request_end(rsp):
 
 @ldp.route('/<path:uid>', methods=['GET'], strict_slashes=False)
 @ldp.route('/', defaults={'uid': '/'}, methods=['GET'], strict_slashes=False)
-@ldp.route('/<path:uid>/fcr:metadata', defaults={'force_rdf' : True},
+@ldp.route('/<path:uid>/fcr:metadata', defaults={'out_fmt' : 'rdf'},
+        methods=['GET'])
+@ldp.route('/<path:uid>/fcr:content', defaults={'out_fmt' : 'non_rdf'},
         methods=['GET'])
-def get_resource(uid, force_rdf=False):
+def get_resource(uid, out_fmt=None):
     '''
     https://www.w3.org/TR/ldp/#ldpr-HTTP_GET
 
@@ -137,16 +139,21 @@ def get_resource(uid, force_rdf=False):
     except TombstoneError as e:
         return _tombstone_response(e, uid)
     else:
+        if out_fmt is None:
+            out_fmt = (
+                    'rdf'
+                    if isinstance(rsrc, LdpRs) or is_accept_hdr_rdf_parsable()
+                    else 'non_rdf')
         out_headers.update(_headers_from_metadata(rsrc))
         uri = g.tbox.uid_to_uri(uid)
-        if (
-                isinstance(rsrc, LdpRs)
-                or is_accept_hdr_rdf_parsable()
-                or force_rdf):
+        if out_fmt == 'rdf':
             ggr = g.tbox.globalize_graph(rsrc.out_graph)
             ggr.namespace_manager = nsm
             return _negotiate_content(ggr, out_headers, uid=uid, uri=uri)
         else:
+            if not getattr(rsrc, 'filename', False):
+                return ('{} has no binary content.'.format(rsrc.uid), 404)
+
             logger.info('Streaming out binary content.')
             rsp = make_response(send_file(
                     rsrc.local_path, as_attachment=True,

lakesuperior/endpoints/templates/resource.html

@@ -23,6 +23,13 @@
 </nav>
 {% endblock %}
 {% block content %}
+{% if gr[gr.identifier : nsc['rdf'].type : nsc['ldp'].NonRDFSource] %}
+<div class="pull-right">
+    <a href="{{ gr.identifier }}/fcr:content" class="btn btn-success btn-lg">
+        <span class="glyphicon glyphicon-download" aria-hidden="true"></span>
+        Download Content</a>
+</div>
+{% endif %}
 {% set created_ts = arrow.get(
     gr.value(gr.identifier, nsc['fcrepo'].created)).replace(
     tzinfo='local') %}