schema.org: add uploadDate for VideoObject serialization [+]

This is the remnant of a dead-end in providing more VideoObject structured
data per https://developers.google.com/search/docs/appearance/structured-data/video
since we were getting 'chided' by Google search console. Unfortunately, the
reality is that a record page is not a video watch page (it may contain multiple
videos + focus of page is on wider metadata) and a generic instance doesn't
have video thumbnails and perhaps doesn't want to expose video content file too
much. All of this resulted in only implementing the uploadDate field 🤷 .

invenio_rdm_records/resources/serializers/schemaorg/schema.py

@@ -199,6 +199,7 @@ class SchemaorgSchema(BaseSerializerSchema, CommonFieldsMixin):
     # Fields that are specific to certain resource types.
     measurementTechnique = fields.Method("get_measurement_techniques")
     distribution = fields.Method("get_distribution")
+    uploadDate = fields.Method("get_upload_date")
 
     def get_id(self, obj):
         """Get id. Use the DOI expressed as a URL."""
@@ -425,7 +426,7 @@ def get_sameAs(self, obj):
         return ids or missing
 
     def get_url(self, obj):
-        """Get Zenodo URL of the record."""
+        """Get URL of the record."""
         self_url = py_.get(obj, "links.self_html")
         return self_url or missing
 
@@ -504,3 +505,17 @@ def _filter_related_identifier_type(self, identifiers, relation_types):
             lambda x: x.get("relation_type", {}).get("id") in relation_types,
             identifiers,
         )
+
+    # Fields specific to https://schema.org/VideoObject
+    # Useful for video crawlers per
+    # https://developers.google.com/search/docs/appearance/structured-data/video
+    def _is_video(self, obj):
+        return self.get_type(obj) == "https://schema.org/VideoObject"
+
+    def get_upload_date(self, obj):
+        """Get uploadDate."""
+        if not self._is_video(obj):
+            return missing
+
+        # Creation date is closest in meaning to when video was uploaded
+        return self.get_creation_date(obj)