Merge pull request #23 from AtomGraph/fix-to-graph-jsonld-array

Fix to graph jsonld array

Author: namedgraph

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "web-algebra"
-version = "1.4.0"
+version = "1.4.1"
 description = "Composable RDF operations in JSON"
 readme = "README.md"
 license = "Apache-2.0"

src/web_algebra/operation.py

@@ -222,18 +222,23 @@ def to_graph(data: Any, *, base: Optional[str] = None) -> Graph:
         already a `Graph` (e.g. the output of an upstream op such as CONSTRUCT)
         passes through unchanged.
 
+        Both shapes of JSON-LD document are accepted: a single node object
+        (`dict`) and a top-level array of nodes (`list`) — the latter is what
+        SPARQL DESCRIBE/CONSTRUCT over multiple subjects returns. rdflib's
+        JSON-LD parser handles both natively.
+
         `base` is the document's base IRI — typically the target URL of the
         enclosing op — used to resolve any relative IRIs in the JSON-LD.
         """
         if isinstance(data, Graph):
             return data
-        if isinstance(data, dict):
+        if isinstance(data, (dict, list)):
             graph = Graph()
             graph.parse(data=json.dumps(data), format="json-ld", publicID=base)
             return graph
         raise TypeError(
             f"Cannot convert {type(data).__name__} to Graph; "
-            "expected a JSON-LD dict or an rdflib.Graph"
+            "expected a JSON-LD dict/list or an rdflib.Graph"
         )
 
     @staticmethod

tests/unit/test_to_graph.py

@@ -10,12 +10,14 @@
 
 import pytest
 from rdflib import Graph, URIRef
+from rdflib.namespace import RDF
 
 from web_algebra.operation import Operation
 
 DOC_URI = URIRef("https://example.org/doc/")
 PROV_GENERATED_BY = URIRef("http://www.w3.org/ns/prov#wasGeneratedBy")
 ACTIVITY_URI = URIRef("https://example.org/activity/#this")
+DOC_TYPE = URIRef("https://example.org/T")
 
 
 class TestToGraph:
@@ -30,6 +32,20 @@ def test_dict_is_parsed_as_jsonld(self):
         assert isinstance(graph, Graph)
         assert (DOC_URI, PROV_GENERATED_BY, ACTIVITY_URI) in graph
 
+    def test_top_level_array_is_parsed_as_jsonld(self):
+        # SPARQL DESCRIBE/CONSTRUCT over multiple subjects returns a top-level
+        # JSON-LD array of nodes; to_graph must accept it, not raise.
+        data = [
+            {"@id": str(DOC_URI), "@type": [str(DOC_TYPE)]},
+            {"@id": str(ACTIVITY_URI), str(PROV_GENERATED_BY): {"@id": str(DOC_URI)}},
+        ]
+
+        graph = Operation.to_graph(data)
+
+        assert isinstance(graph, Graph)
+        assert (DOC_URI, RDF.type, DOC_TYPE) in graph
+        assert (ACTIVITY_URI, PROV_GENERATED_BY, DOC_URI) in graph
+
     def test_graph_passes_through_unchanged(self):
         # An upstream op (e.g. CONSTRUCT) already produced a Graph — identity.
         g = Graph()