From e32f8ff3e537bda306e7794fdce2b1305be621ff Mon Sep 17 00:00:00 2001
From: Birger Schacht <birger.schacht@oeaw.ac.at>
Date: Wed, 18 Dec 2024 13:51:21 +0100
Subject: [PATCH] feat(generic): refactor GenericRDFBaseRenderer and add CIDOC
 renderers

The GenericRDFBaseRenderer now uses graphs instead of working with
triples. Additionaly it is possible to override the serialization format
by setting the renderers `rdflib_format` attribute. If this is not set,
the serialization uses the `format` attribute from the renderer as
serialization format.
---
 apis_core/generic/renderers.py | 78 ++++++++++++++++++++++++++++------
 1 file changed, 65 insertions(+), 13 deletions(-)

diff --git a/apis_core/generic/renderers.py b/apis_core/generic/renderers.py
index 30a300ca6..696c994f4 100644
--- a/apis_core/generic/renderers.py
+++ b/apis_core/generic/renderers.py
@@ -2,32 +2,84 @@
 
 from rdflib import Graph
 from rest_framework import renderers
+from rest_framework.exceptions import APIException
 
 logger = logging.getLogger(__name__)
 
 
 class GenericRDFBaseRenderer(renderers.BaseRenderer):
+    """
+    Base class to render RDF graphs to various formats.
+    This renderer expects the serialized data to either be a rdflib grap **or**
+    to contain a list of rdflib graphs. If it works with a list of graphs, those
+    are combined to one graph.
+    This graph is then serialized and the result is returned. The serialization
+    format can be set using the `rdflib_format` attribute. If this is not set, the
+    `format` attribute of the renderer is used as serialization format (this is the
+    format as it is used by the Django Rest Framework for content negotiation.
+    """
+
+    format = "ttl"
+    rdflib_format = None
+
     def render(self, data, accepted_media_type=None, renderer_context=None):
-        g = Graph()
-        for result in data.get("results", []):
-            match result:
-                case tuple(_, _, _):
-                    g.add(result)
-                case other:
-                    logger.debug("Could not add %s to RDF graph: not a tuple", other)
-        return g.serialize(format=self.media_type)
+        result = Graph()
 
+        match data:
+            case {"results": results, **rest}:  # noqa: F841
+                # Handle case where data is a dict with multiple graphs
+                for graph in results:
+                    if isinstance(graph, Graph):
+                        # Merge triples
+                        for triple in graph:
+                            result.add(triple)
+                        # Merge namespace bindings
+                        for prefix, namespace in graph.namespaces():
+                            result.bind(prefix, namespace, override=False)
+            case {"detail": detail}:
+                raise APIException(detail)
+            case Graph():
+                # Handle case where data is a single graph
+                result = data
+                # Ensure namespaces are properly bound in the single graph case
+                for prefix, namespace in data.namespaces():
+                    result.bind(prefix, namespace, override=False)
+            case _:
+                raise ValueError(
+                    "Invalid data format. Expected rdflib Graph or dict with 'results' key containing graphs"
+                )
+        return result.serialize(format=self.graph_format)
 
-class GenericRDFXMLRenderer(GenericRDFBaseRenderer):
-    media_type = "application/rdf+xml"
-    format = "rdf+xml"
+    @property
+    def graph_format(self):
+        return self.rdflib_format or self.format
 
 
 class GenericRDFTurtleRenderer(GenericRDFBaseRenderer):
+    format = "ttl"
     media_type = "text/turtle"
-    format = "rdf+turtle"
+    rdflib_format = "turtle"
+
+
+class GenericRDFXMLRenderer(GenericRDFBaseRenderer):
+    format = "rdf"
+    media_type = "application/rdf+xml"
+    rdflib_format = "xml"
 
 
 class GenericRDFN3Renderer(GenericRDFBaseRenderer):
+    format = "rdf"
     media_type = "text/n3"
-    format = "rdf+n3"
+    rdflib_format = "n3"
+
+
+class CidocTTLRenderer(GenericRDFBaseRenderer):
+    format = "cidoc"
+    media_type = "text/ttl"
+    rdflib_format = "ttl"
+
+
+class CidocXMLRenderer(GenericRDFBaseRenderer):
+    format = "cidoc"
+    media_type = "application/rdf+xml"
+    rdflib_format = "xml"