make linktemplate rules assume blank nodes

Author: rob-metalinkage

_sources/v1/schemas/linkTemplate/bblock.json

@@ -16,5 +16,5 @@
     "ogcapi-records",
     "records"
   ],
-  "abstract": "This building block corresponds to the schema for an OGC API Records linkTemplate"
+  "abstract": "This building block corresponds to the schema for an OGC API Records linkTemplate."
 }

_sources/v1/schemas/linkTemplate/description.md

@@ -0,0 +1,11 @@
+## Link Template
+
+### JSON-LD mapping
+
+This Building block maps variables to **blank nodes** - this means that multiple mappings can co-exist in a system without clashing, even if the same variable name is re-used.
+
+(if identification of variables is required at a global level @id can be used in variable names)
+
+### Tests:
+ 
+tests if variables present in uriTemplates exist in variable declarations using SHACL

_sources/v1/schemas/linkTemplate/example.json

@@ -14,6 +14,7 @@
       "maxItems": 4
     },
     "crs": {
+      "@id": "https://org.org/some-standard-param-set/crs",
       "description": "...",
       "type": "string",
       "enum": [

_sources/v1/schemas/linkTemplate/rules.shacl

@@ -17,14 +17,13 @@ rec:testVarExists
       SELECT $this ?path ?value ?template
       WHERE {
         BIND (rec:hasVariable as ?path)
-        $this rec:hasVariable ?var .
+        $this rec:hasVariable/dct:identifier ?var .
         $this rec:uriTemplate ?template .
-        BIND ( STRAFTER ( STR(?var),STR( rec: ) ) AS ?value )
       }
       GROUP BY $this ?path ?value ?template
-      HAVING ( COUNT(?var) = SUM(
+      HAVING ( COUNT(?var) != SUM(
          IF(
-            CONTAINS(?template, CONCAT("{",?value,"}"  )),1,0 )
+            CONTAINS(?template, CONCAT("{",?var,"}"  )),1,0 )
   ) )
 
     """ ; ]

_sources/v1/schemas/linkTemplate/tests/var-exists-fail.json

@@ -0,0 +1,17 @@
+{
+  "rel": "describes",
+  "title": "World Ozone and Ultraviolet Radiation Data Centre (WOUDC) stations",
+  "uriTemplate": "https://geo.woudc.org/ows?crs={crs}&bbox={bbox}",
+  "variables": {
+    "bbox": {
+      "description": "...",
+      "type": "array",
+      "items": {
+        "type": "number",
+        "format": "double"
+      },
+      "minItems": 4,
+      "maxItems": 4
+    }
+  }
+}

_sources/v1/schemas/linkTemplate/tests/var-exists-fail.ttl

@@ -0,0 +1,28 @@
+import rdflib
+
+
+g = rdflib.Graph()
+g.parse('build-local/tests/api/records/v1/schemas/linkTemplate/var-exists-fail.ttl', format='turtle')
+
+# Define the SPARQL query
+query = """
+            PREFIX rec:    <https://www.opengis.net/def/ogc-api/records/>
+      prefix oa: <http://www.w3.org/ns/oa#>
+      SELECT COUNT(?var) 
+      WHERE {
+        BIND (rec:hasVariable as ?path)
+        $this rec:hasVariable/dct:identifier ?var .
+        $this rec:uriTemplate ?template .
+        
+      }
+      GROUP BY $this ?path ?value ?template
+      
+"""
+
+# Run the query against the local graph
+qres = g.query(query)
+
+for row in qres:
+    print(f"Subject: {row.s}, Predicate: {row.p}, Object: {row.o}")
+    # Or by index:
+    # print(f"Subject: {row[0]}, Predicate: {row[1]}, Object: {row[2]}")