replace incomplete example in intro_to_sparql.rst
@@ -17,55 +17,61 @@ Queries can be evaluated against a graph with the
:meth:`rdflib.graph.Graph.update`.
The query method returns a :class:`rdflib.query.Result` instance. For
-SELECT queries, iterating over this return
+SELECT queries, iterating over this returns
:class:`rdflib.query.ResultRow` instances, each containing a set of
variable bindings. For CONSTRUCT/DESCRIBE queries, iterating over the
-result object gives the triples. For ASK queries, iterating will yield
-the single boolean answer, or evaluating the result object in a
-boolean-context (i.e. ``bool(result)``)
+result object yields triples. For ASK queries, the single Boolean
+answer is obtained by iterating over the result object or by
+evaluating the result object in a Boolean context
+(i.e. ``bool(result)``).
-Continuing the example...
+Consider the example...
.. code-block:: python
import rdflib
-
g = rdflib.Graph()
+ g.parse("http://danbri.org/foaf.rdf#")
- # ... add some triples to g somehow ...
- g.parse("some_foaf_file.rdf")
-
- qres = g.query(
- """SELECT DISTINCT ?aname ?bname
+ knows_query = """
+ SELECT DISTINCT ?aname ?bname
WHERE {
?a foaf:knows ?b .
?a foaf:name ?aname .
?b foaf:name ?bname .
- }""")
+ }"""
- for row in qres:
+ for row in g.query(knows_query):
print("%s knows %s" % row)
The results are tuples of values in the same order as your SELECT
-arguments. Alternatively, the values can be accessed by variable
-name, either as attributes, or as items: ``row.b`` and ``row["b"]`` is
-equivalent.
+arguments. The values can be accessed individually by variable
+name, either as attributes (``row.b``) or as items (``row["b"]``).
.. code-block:: text
- Timothy Berners-Lee knows Edd Dumbill
- Timothy Berners-Lee knows Jennifer Golbeck
- Timothy Berners-Lee knows Nicholas Gibbins
- Timothy Berners-Lee knows Nigel Shadbolt
- Dan Brickley knows binzac
- Timothy Berners-Lee knows Eric Miller
- Drew Perttula knows David McClosky
- Timothy Berners-Lee knows Dan Connolly
+ Dan Brickley knows Tim Berners-Lee
+ Dan Brickley knows Dean Jackson
+ Dan Brickley knows Mischa Tuffield
+ Dan Brickley knows Ludovic Hirlimann
+ Dan Brickley knows Libby Miller
...
As an alternative to using ``PREFIX`` in the SPARQL query, namespace
-bindings can be passed in with the ``initNs`` kwarg, see
-:doc:`namespaces_and_bindings`.
+bindings can be passed in with the ``initNs`` kwarg (see
+:doc:`namespaces_and_bindings`):
+
+.. code-block:: python
+
+ import rdflib
+ from rdflib import FOAF
+ g = rdflib.Graph()
+ g.parse("http://danbri.org/foaf.rdf#")
+
+ result = g.query(knows_query, initNs={ 'foaf': FOAF })
+
+ for row in result:
+ print(f"{row.aname} knows {row['bname']}")
Variables can also be pre-bound, using ``initBindings`` kwarg can be
used to pass in a ``dict`` of initial bindings, this is particularly
