refactor(serializers.dcat): extend checksum with spdx clauses

* add spdx clauses as parents classes and properties to checksum.

* add XML namespace prefix spdx and binds it to the SPDX RDF vocabulary at that base IRI.

Author: Mahmoud Hassan

invenio_rdm_records/resources/serializers/dcat/__init__.py

@@ -75,31 +75,50 @@ def access_url(file):
             url = file.get("access_url")
             return {"{{{rdf}}}resource".format(**ns): url} if url else None
 
-        def checksum(file):
-            return file["checksum"] if file.get("checksum") else None
-
         files_fields = {
             "{{{dcat}}}downloadURL": download_url,
             "{{{dcat}}}mediaType": media_type,
             "{{{dcat}}}byteSize": byte_size,
             "{{{dcat}}}accessURL": access_url,
-            "{{{dcat}}}checksum": checksum,
         }
 
-        for f in files:
+        for file in files:
             dist_wrapper = ET.SubElement(root[0], "{{{dcat}}}distribution".format(**ns))
             dist = ET.SubElement(dist_wrapper, "{{{dcat}}}Distribution".format(**ns))
 
             for tag, func in files_fields.items():
-                tag_value = func(f)
-
+                tag_value = func(file)
                 if tag_value:
                     el = ET.SubElement(dist, tag.format(**ns))
                     if isinstance(tag_value, str):
                         el.text = tag_value
                     if isinstance(tag_value, dict):
                         el.attrib.update(tag_value)
 
+            checksum = file.get("checksum") if file.get("checksum") else None
+            if checksum:
+                value = checksum.split(":")[1]
+                spdx_checksum_el = ET.SubElement(
+                    dist, "{{{spdx}}}checksum".format(**ns)
+                )
+                spdx_checksum_obj = ET.SubElement(
+                    spdx_checksum_el, "{{{spdx}}}Checksum".format(**ns)
+                )
+
+                algo_el = ET.SubElement(
+                    spdx_checksum_obj,
+                    "{{{spdx}}}algorithm".format(**ns),
+                )
+                algo_el.attrib["{{{rdf}}}resource".format(**ns)] = (
+                    f"http://spdx.org/rdf/terms#checksumAlgorithm_md5"
+                )
+
+                value_el = ET.SubElement(
+                    spdx_checksum_obj,
+                    "{{{spdx}}}checksumValue".format(**ns),
+                )
+                value_el.text = value
+
     def add_missing_creatibutor_links(self, rdf_tree):
         """Add missing `rdf:about` attributes to <rdf:Description> within <dct:creator> and <dct:contributor> and <foaf:Organization> within <org:memberOf>."""
         namespaces = rdf_tree.nsmap

invenio_rdm_records/resources/serializers/dcat/datacite-to-dcat-ap.xsl

@@ -53,6 +53,7 @@
     xmlns:dct    = "http://purl.org/dc/terms/"
     xmlns:dctype = "http://purl.org/dc/dcmitype/"
     xmlns:dcat   = "http://www.w3.org/ns/dcat#"
+    xmlns:spdx   = "http://spdx.org/rdf/terms#"
     xmlns:foaf   = "http://xmlns.com/foaf/0.1/"
     xmlns:gsp    = "http://www.opengis.net/ont/geosparql#"
     xmlns:locn   = "http://www.w3.org/ns/locn#"

tests/resources/serializers/test_dcat_serializer.py

@@ -40,6 +40,7 @@ def test_dcat_serializer(running_app, full_record_to_dict):
         'xmlns:dct="http://purl.org/dc/terms/" '
         'xmlns:dctype="http://purl.org/dc/dcmitype/" '
         'xmlns:dcat="http://www.w3.org/ns/dcat#" '
+        'xmlns:spdx="http://spdx.org/rdf/terms#" '
         'xmlns:foaf="http://xmlns.com/foaf/0.1/" '
         'xmlns:gsp="http://www.opengis.net/ont/geosparql#" '
         'xmlns:locn="http://www.w3.org/ns/locn#" '
@@ -253,7 +254,13 @@ def test_dcat_serializer(running_app, full_record_to_dict):
         "        <dcat:byteSize>9</dcat:byteSize>\n"
         "        <dcat:accessURL "
         'rdf:resource="https://doi.org/10.1234/12345-abcde"/>\n'
-        "        <dcat:checksum>md5:e795abeef2c38de2b064be9f6364ceae</dcat:checksum>\n"
+        "        <spdx:checksum>\n"
+        "          <spdx:Checksum>\n"
+        "            <spdx:algorithm "
+        'rdf:resource="http://spdx.org/rdf/terms#checksumAlgorithm_md5"/>\n'
+        "            <spdx:checksumValue>e795abeef2c38de2b064be9f6364ceae</spdx:checksumValue>\n"
+        "          </spdx:Checksum>\n"
+        "        </spdx:checksum>\n"
         "      </dcat:Distribution>\n"
         "    </dcat:distribution>\n"
         "  </rdf:Description>\n"