"""
This is an RDFLib store around Ivan Herman et al.'s SPARQL service wrapper.
This was first done in layer-cake, and then ported to RDFLib
"""
from __future__ import annotations
import collections
import re
from typing import (
TYPE_CHECKING,
Any,
Callable,
Dict,
Generator,
Iterable,
Iterator,
List,
Mapping,
Optional,
Tuple,
Union,
overload,
)
from rdflib.graph import DATASET_DEFAULT_GRAPH_ID, Graph
from rdflib.plugins.stores.regexmatching import NATIVE_REGEX
from rdflib.store import Store
from rdflib.term import BNode, Identifier, Node, URIRef, Variable
if TYPE_CHECKING:
import typing_extensions as te # noqa: I001
from rdflib.graph import (
_TripleType,
_ContextType,
_QuadType,
_TriplePatternType,
_SubjectType,
_PredicateType,
_ObjectType,
_ContextIdentifierType,
)
from rdflib.plugins.sparql.sparql import Query, Update
from rdflib.query import Result, ResultRow
from .sparqlconnector import SPARQLConnector
# Defines some SPARQL keywords
LIMIT = "LIMIT"
OFFSET = "OFFSET"
ORDERBY = "ORDER BY"
BNODE_IDENT_PATTERN = re.compile(r"(?P<label>_\:[^\s]+)")
_NodeToSparql = Callable[["Node"], str]
def _node_to_sparql(node: Node) -> str:
if isinstance(node, BNode):
raise Exception(
"SPARQLStore does not support BNodes! "
"See http://www.w3.org/TR/sparql11-query/#BGPsparqlBNodes"
)
return node.n3()
[docs]class SPARQLStore(SPARQLConnector, Store):
"""An RDFLib store around a SPARQL endpoint
This is context-aware and should work as expected
when a context is specified.
For ConjunctiveGraphs, reading is done from the "default graph". Exactly
what this means depends on your endpoint, because SPARQL does not offer a
simple way to query the union of all graphs as it would be expected for a
ConjuntiveGraph. This is why we recommend using Dataset instead, which is
motivated by the SPARQL 1.1.
Fuseki/TDB has a flag for specifying that the default graph
is the union of all graphs (``tdb:unionDefaultGraph`` in the Fuseki config).
.. warning:: By default the SPARQL Store does not support blank-nodes!
As blank-nodes act as variables in SPARQL queries,
there is no way to query for a particular blank node without
using non-standard SPARQL extensions.
See http://www.w3.org/TR/sparql11-query/#BGPsparqlBNodes
You can make use of such extensions through the ``node_to_sparql``
argument. For example if you want to transform BNode('0001') into
"<bnode:b0001>", you can use a function like this:
>>> def my_bnode_ext(node):
... if isinstance(node, BNode):
... return '<bnode:b%s>' % node
... return _node_to_sparql(node)
>>> store = SPARQLStore('http://dbpedia.org/sparql',
... node_to_sparql=my_bnode_ext)
You can request a particular result serialization with the
``returnFormat`` parameter. This is a string that must have a
matching plugin registered. Built in is support for ``xml``,
``json``, ``csv``, ``tsv`` and ``application/rdf+xml``.
The underlying SPARQLConnector uses the urllib library.
Any extra kwargs passed to the SPARQLStore connector are passed to
urllib when doing HTTP calls. I.e. you have full control of
cookies/auth/headers.
Form example:
>>> store = SPARQLStore('...my endpoint ...', auth=('user','pass'))
will use HTTP basic auth.
"""
formula_aware = False
transaction_aware = False
graph_aware = True
regex_matching = NATIVE_REGEX
[docs] def __init__(
self,
query_endpoint: Optional[str] = None,
sparql11: bool = True,
context_aware: bool = True,
node_to_sparql: _NodeToSparql = _node_to_sparql,
returnFormat: str = "xml", # noqa: N803
auth: Optional[Tuple[str, str]] = None,
**sparqlconnector_kwargs,
):
super(SPARQLStore, self).__init__(
query_endpoint=query_endpoint,
returnFormat=returnFormat,
auth=auth,
**sparqlconnector_kwargs,
)
self.node_to_sparql = node_to_sparql
self.nsBindings: Dict[str, Any] = {}
self.sparql11 = sparql11
self.context_aware = context_aware
self.graph_aware = context_aware
self._queries = 0
# type error: Missing return statement
[docs] def open(self, configuration: str, create: bool = False) -> Optional[int]: # type: ignore[return]
"""This method is included so that calls to this Store via Graph, e.g. Graph("SPARQLStore"),
can set the required parameters
"""
if type(configuration) == str: # noqa: E721
self.query_endpoint = configuration
else:
raise Exception(
"configuration must be a string (a single query endpoint URI)"
)
# Database Management Methods
[docs] def create(self, configuration: str) -> None:
raise TypeError(
"The SPARQL Store is read only. Try SPARQLUpdateStore for read/write."
)
[docs] def destroy(self, configuration: str) -> None:
raise TypeError("The SPARQL store is read only")
# Transactional interfaces
[docs] def commit(self) -> None:
raise TypeError("The SPARQL store is read only")
[docs] def rollback(self) -> None:
raise TypeError("The SPARQL store is read only")
[docs] def add(
self, _: _TripleType, context: _ContextType = None, quoted: bool = False
) -> None:
raise TypeError("The SPARQL store is read only")
[docs] def addN(self, quads: Iterable[_QuadType]) -> None: # noqa: N802
raise TypeError("The SPARQL store is read only")
# type error: Signature of "remove" incompatible with supertype "Store"
[docs] def remove( # type: ignore[override]
self, _: _TriplePatternType, context: Optional[_ContextType]
) -> None:
raise TypeError("The SPARQL store is read only")
# type error: Signature of "update" incompatible with supertype "SPARQLConnector"
[docs] def update( # type: ignore[override]
self,
query: Union[Update, str],
initNs: Dict[str, Any] = {}, # noqa: N803
initBindings: Dict[str, Identifier] = {}, # noqa: N803
queryGraph: Identifier = None, # noqa: N803
DEBUG: bool = False, # noqa: N803
) -> None:
raise TypeError("The SPARQL store is read only")
def _query(self, *args: Any, **kwargs: Any) -> Result:
self._queries += 1
return super(SPARQLStore, self).query(*args, **kwargs)
def _inject_prefixes(self, query: str, extra_bindings: Mapping[str, Any]) -> str:
bindings = set(list(self.nsBindings.items()) + list(extra_bindings.items()))
if not bindings:
return query
return "\n".join(
[
"\n".join(["PREFIX %s: <%s>" % (k, v) for k, v in bindings]),
"", # separate ns_bindings from query with an empty line
query,
]
)
# type error: Signature of "query" incompatible with supertype "SPARQLConnector"
# type error: Signature of "query" incompatible with supertype "Store"
[docs] def query( # type: ignore[override]
self,
query: Union[Query, str],
initNs: Optional[Mapping[str, Any]] = None, # noqa: N803
initBindings: Optional[Mapping[str, Identifier]] = None, # noqa: N803
queryGraph: Optional[str] = None, # noqa: N803
DEBUG: bool = False, # noqa: N803
) -> Result:
self.debug = DEBUG
assert isinstance(query, str)
if initNs is not None and len(initNs) > 0:
query = self._inject_prefixes(query, initNs)
if initBindings:
if not self.sparql11:
raise Exception("initBindings not supported for SPARQL 1.0 Endpoints.")
v = list(initBindings)
# VALUES was added to SPARQL 1.1 on 2012/07/24
query += "\nVALUES ( %s )\n{ ( %s ) }\n" % (
" ".join("?" + str(x) for x in v),
" ".join(self.node_to_sparql(initBindings[x]) for x in v),
)
return self._query(
query, default_graph=queryGraph if self._is_contextual(queryGraph) else None
)
# type error: Return type "Iterator[Tuple[Tuple[Node, Node, Node], None]]" of "triples" incompatible with return type "Iterator[Tuple[Tuple[Node, Node, Node], Iterator[Optional[Graph]]]]"
[docs] def triples( # type: ignore[override]
self, spo: _TriplePatternType, context: Optional[_ContextType] = None
) -> Iterator[Tuple[_TripleType, None]]:
"""
- tuple **(s, o, p)**
the triple used as filter for the SPARQL select.
(None, None, None) means anything.
- context **context**
the graph effectively calling this method.
Returns a tuple of triples executing essentially a SPARQL like
SELECT ?subj ?pred ?obj WHERE { ?subj ?pred ?obj }
**context** may include three parameter
to refine the underlying query:
* LIMIT: an integer to limit the number of results
* OFFSET: an integer to enable paging of results
* ORDERBY: an instance of Variable('s'), Variable('o') or Variable('p') or, by default, the first 'None' from the given triple
.. warning::
- Using LIMIT or OFFSET automatically include ORDERBY otherwise this is
because the results are retrieved in a not deterministic way (depends on
the walking path on the graph)
- Using OFFSET without defining LIMIT will discard the first OFFSET - 1 results
.. code-block:: python
a_graph.LIMIT = limit
a_graph.OFFSET = offset
triple_generator = a_graph.triples(mytriple):
# do something
# Removes LIMIT and OFFSET if not required for the next triple() calls
del a_graph.LIMIT
del a_graph.OFFSET
"""
s, p, o = spo
vars = []
if not s:
s = Variable("s")
vars.append(s)
if not p:
p = Variable("p")
vars.append(p)
if not o:
o = Variable("o")
vars.append(o)
if vars:
v = " ".join([term.n3() for term in vars])
verb = "SELECT %s " % v
else:
verb = "ASK"
nts = self.node_to_sparql
query = "%s { %s %s %s }" % (verb, nts(s), nts(p), nts(o))
# The ORDER BY is necessary
if (
hasattr(context, LIMIT)
or hasattr(context, OFFSET)
or hasattr(context, ORDERBY)
):
var = None
if isinstance(s, Variable):
var = s
elif isinstance(p, Variable):
var = p
elif isinstance(o, Variable):
var = o
elif hasattr(context, ORDERBY) and isinstance(
getattr(context, ORDERBY), Variable
):
var = getattr(context, ORDERBY)
# type error: Item "None" of "Optional[Variable]" has no attribute "n3"
query = query + " %s %s" % (ORDERBY, var.n3()) # type: ignore[union-attr]
try:
query = query + " LIMIT %s" % int(getattr(context, LIMIT))
except (ValueError, TypeError, AttributeError):
pass
try:
query = query + " OFFSET %s" % int(getattr(context, OFFSET))
except (ValueError, TypeError, AttributeError):
pass
result = self._query(
query,
# type error: Item "None" of "Optional[Graph]" has no attribute "identifier"
default_graph=context.identifier if self._is_contextual(context) else None, # type: ignore[union-attr]
)
if vars:
if type(result) == tuple:
if result[0] == 401:
raise ValueError(
"It looks like you need to authenticate with this SPARQL Store. HTTP unauthorized"
)
for row in result:
if TYPE_CHECKING:
# This will be a ResultRow because if vars is truthish then
# the query will be a SELECT query.
assert isinstance(row, ResultRow)
yield (
# type error: No overload variant of "get" of "ResultRow" matches argument types "Node", "Node"
row.get(s, s), # type: ignore[call-overload]
row.get(p, p), # type: ignore[call-overload]
row.get(o, o), # type: ignore[call-overload]
), None # why is the context here not the passed in graph 'context'?
else:
if result.askAnswer:
yield (s, p, o), None
[docs] def triples_choices(
self,
_: Tuple[
Union[_SubjectType, List[_SubjectType]],
Union[_PredicateType, List[_PredicateType]],
Union[_ObjectType, List[_ObjectType]],
],
context: Optional[_ContextType] = None,
) -> Generator[
Tuple[
Tuple[_SubjectType, _PredicateType, _ObjectType],
Iterator[Optional[_ContextType]],
],
None,
None,
]:
"""
A variant of triples that can take a list of terms instead of a
single term in any slot. Stores can implement this to optimize
the response time from the import default 'fallback' implementation,
which will iterate over each term in the list and dispatch to
triples.
"""
raise NotImplementedError("Triples choices currently not supported")
[docs] def __len__(self, context: Optional[_ContextType] = None) -> int:
if not self.sparql11:
raise NotImplementedError(
"For performance reasons, this is not"
+ "supported for sparql1.0 endpoints"
)
else:
q = "SELECT (count(*) as ?c) WHERE {?s ?p ?o .}"
result = self._query(
q,
# type error: Item "None" of "Optional[Graph]" has no attribute "identifier"
default_graph=(
context.identifier # type: ignore[union-attr]
if self._is_contextual(context)
else None
),
)
# type error: Item "Tuple[Node, ...]" of "Union[Tuple[Node, Node, Node], bool, ResultRow]" has no attribute "c"
return int(next(iter(result)).c) # type: ignore[union-attr]
# type error: Return type "Generator[Identifier, None, None]" of "contexts" incompatible with return type "Generator[Graph, None, None]" in supertype "Store"
[docs] def contexts( # type: ignore[override]
self, triple: Optional[_TripleType] = None
) -> Generator[_ContextIdentifierType, None, None]:
"""
Iterates over results to "SELECT ?NAME { GRAPH ?NAME { ?s ?p ?o } }"
or "SELECT ?NAME { GRAPH ?NAME {} }" if triple is `None`.
Returns instances of this store with the SPARQL wrapper
object updated via addNamedGraph(?NAME).
This causes a named-graph-uri key / value pair to be sent over
the protocol.
Please note that some SPARQL endpoints are not able to find empty named
graphs.
"""
if triple:
nts = self.node_to_sparql
s, p, o = triple
params = (
nts(s if s else Variable("s")),
nts(p if p else Variable("p")),
nts(o if o else Variable("o")),
)
q = "SELECT ?name WHERE { GRAPH ?name { %s %s %s }}" % params
else:
q = "SELECT ?name WHERE { GRAPH ?name {} }"
result = self._query(q)
# type error: Item "bool" of "Union[Tuple[Node, Node, Node], bool, ResultRow]" has no attribute "name"
# error: Generator has incompatible item type "Union[Any, Identifier]"; expected "IdentifiedNode"
return (row.name for row in result) # type: ignore[union-attr,misc]
# Namespace persistence interface implementation
[docs] def bind(self, prefix: str, namespace: URIRef, override: bool = True) -> None:
bound_prefix = self.prefix(namespace)
if override and bound_prefix:
del self.nsBindings[bound_prefix]
self.nsBindings[prefix] = namespace
[docs] def prefix(self, namespace: URIRef) -> Optional[str]:
""" """
return dict([(v, k) for k, v in self.nsBindings.items()]).get(namespace)
[docs] def namespace(self, prefix: str) -> Optional[URIRef]:
return self.nsBindings.get(prefix)
[docs] def namespaces(self) -> Iterator[Tuple[str, URIRef]]:
for prefix, ns in self.nsBindings.items():
yield prefix, ns
[docs] def add_graph(self, graph: Graph) -> None:
raise TypeError("The SPARQL store is read only")
[docs] def remove_graph(self, graph: Graph) -> None:
raise TypeError("The SPARQL store is read only")
@overload
def _is_contextual(self, graph: None) -> te.Literal[False]: ...
@overload
def _is_contextual(self, graph: Optional[Union[Graph, str]]) -> bool: ...
def _is_contextual(self, graph: Optional[Union[Graph, str]]) -> bool:
"""Returns `True` if the "GRAPH" keyword must appear
in the final SPARQL query sent to the endpoint.
"""
if (not self.context_aware) or (graph is None):
return False
if isinstance(graph, str):
return graph != "__UNION__"
else:
return graph.identifier != DATASET_DEFAULT_GRAPH_ID
[docs] def subjects(
self,
predicate: Optional[_PredicateType] = None,
object: Optional[_ObjectType] = None,
) -> Generator[_SubjectType, None, None]:
"""A generator of subjects with the given predicate and object"""
for t, c in self.triples((None, predicate, object)):
yield t[0]
[docs] def predicates(
self,
subject: Optional[_SubjectType] = None,
object: Optional[_ObjectType] = None,
) -> Generator[_PredicateType, None, None]:
"""A generator of predicates with the given subject and object"""
for t, c in self.triples((subject, None, object)):
yield t[1]
[docs] def objects(
self,
subject: Optional[_SubjectType] = None,
predicate: Optional[_PredicateType] = None,
) -> Generator[_ObjectType, None, None]:
"""A generator of objects with the given subject and predicate"""
for t, c in self.triples((subject, predicate, None)):
yield t[2]
[docs] def subject_predicates(
self, object: Optional[_ObjectType] = None
) -> Generator[Tuple[_SubjectType, _PredicateType], None, None]:
"""A generator of (subject, predicate) tuples for the given object"""
for t, c in self.triples((None, None, object)):
yield t[0], t[1]
[docs] def subject_objects(
self, predicate: Optional[_PredicateType] = None
) -> Generator[Tuple[_SubjectType, _ObjectType], None, None]:
"""A generator of (subject, object) tuples for the given predicate"""
for t, c in self.triples((None, predicate, None)):
yield t[0], t[2]
[docs] def predicate_objects(
self, subject: Optional[_SubjectType] = None
) -> Generator[Tuple[_PredicateType, _ObjectType], None, None]:
"""A generator of (predicate, object) tuples for the given subject"""
for t, c in self.triples((subject, None, None)):
yield t[1], t[2]
[docs]class SPARQLUpdateStore(SPARQLStore):
"""A store using SPARQL queries for reading and SPARQL Update for changes.
This can be context-aware, if so, any changes will be to the given named
graph only.
In favor of the SPARQL 1.1 motivated Dataset, we advise against using this
with ConjunctiveGraphs, as it reads and writes from and to the
"default graph". Exactly what this means depends on the endpoint and can
result in confusion.
For Graph objects, everything works as expected.
See the :class:`SPARQLStore` base class for more information.
"""
where_pattern = re.compile(r"""(?P<where>WHERE\s*\{)""", re.IGNORECASE)
##############################################################
# Regex for injecting GRAPH blocks into updates on a context #
##############################################################
# Observations on the SPARQL grammar (http://www.w3.org/TR/2013/REC-sparql11-query-20130321/):
# 1. Only the terminals STRING_LITERAL1, STRING_LITERAL2,
# STRING_LITERAL_LONG1, STRING_LITERAL_LONG2, and comments can contain
# curly braces.
# 2. The non-terminals introduce curly braces in pairs only.
# 3. Unescaped " can occur only in strings and comments.
# 3. Unescaped ' can occur only in strings, comments, and IRIRefs.
# 4. \ always escapes the following character, especially \", \', and
# \\ denote literal ", ', and \ respectively.
# 5. # always starts a comment outside of string and IRI
# 6. A comment ends at the next newline
# 7. IRIREFs need to be detected, as they may contain # without starting a comment
# 8. PrefixedNames do not contain a #
# As a consequence, it should be rather easy to detect strings and comments
# in order to avoid unbalanced curly braces.
# From the SPARQL grammar
STRING_LITERAL1 = "'([^'\\\\]|\\\\.)*'"
STRING_LITERAL2 = '"([^"\\\\]|\\\\.)*"'
STRING_LITERAL_LONG1 = "'''(('|'')?([^'\\\\]|\\\\.))*'''"
STRING_LITERAL_LONG2 = '"""(("|"")?([^"\\\\]|\\\\.))*"""'
String = "(%s)|(%s)|(%s)|(%s)" % (
STRING_LITERAL1,
STRING_LITERAL2,
STRING_LITERAL_LONG1,
STRING_LITERAL_LONG2,
)
IRIREF = '<([^<>"{}|^`\\]\\\\[\\x00-\\x20])*>'
COMMENT = "#[^\\x0D\\x0A]*([\\x0D\\x0A]|\\Z)"
# Simplified grammar to find { at beginning and } at end of blocks
BLOCK_START = "{"
BLOCK_END = "}"
ESCAPED = "\\\\."
# Match anything that doesn't start or end a block:
BlockContent = "(%s)|(%s)|(%s)|(%s)" % (String, IRIREF, COMMENT, ESCAPED)
BlockFinding = "(?P<block_start>%s)|(?P<block_end>%s)|(?P<block_content>%s)" % (
BLOCK_START,
BLOCK_END,
BlockContent,
)
BLOCK_FINDING_PATTERN = re.compile(BlockFinding)
# Note that BLOCK_FINDING_PATTERN.finditer() will not cover the whole
# string with matches. Everything that is not matched will have to be
# part of the modified query as is.
##################################################################
[docs] def __init__(
self,
query_endpoint: Optional[str] = None,
update_endpoint: Optional[str] = None,
sparql11: bool = True,
context_aware: bool = True,
postAsEncoded: bool = True, # noqa: N803
autocommit: bool = True,
dirty_reads: bool = False,
**kwds,
):
"""
:param autocommit if set, the store will commit after every
writing operations. If False, we only make queries on the
server once commit is called.
:param dirty_reads if set, we do not commit before reading. So you
cannot read what you wrote before manually calling commit.
"""
SPARQLStore.__init__(
self,
query_endpoint,
sparql11,
context_aware,
update_endpoint=update_endpoint,
**kwds,
)
self.postAsEncoded = postAsEncoded
self.autocommit = autocommit
self.dirty_reads = dirty_reads
self._edits: Optional[List[str]] = None
self._updates = 0
[docs] def query(self, *args: Any, **kwargs: Any) -> Result:
if not self.autocommit and not self.dirty_reads:
self.commit()
return SPARQLStore.query(self, *args, **kwargs)
# type error: Signature of "triples" incompatible with supertype "Store"
[docs] def triples( # type: ignore[override]
self, *args: Any, **kwargs: Any
) -> Iterator[Tuple[_TripleType, None]]:
if not self.autocommit and not self.dirty_reads:
self.commit()
return SPARQLStore.triples(self, *args, **kwargs)
# type error: Signature of "contexts" incompatible with supertype "Store"
[docs] def contexts( # type: ignore[override]
self, *args: Any, **kwargs: Any
) -> Generator[_ContextIdentifierType, None, None]:
if not self.autocommit and not self.dirty_reads:
self.commit()
return SPARQLStore.contexts(self, *args, **kwargs)
[docs] def __len__(self, *args: Any, **kwargs: Any) -> int:
if not self.autocommit and not self.dirty_reads:
self.commit()
return SPARQLStore.__len__(self, *args, **kwargs)
[docs] def open(
self, configuration: Union[str, Tuple[str, str]], create: bool = False
) -> None:
"""
sets the endpoint URLs for this SPARQLStore
:param configuration: either a tuple of (query_endpoint, update_endpoint),
or a string with the endpoint which is configured as query and update endpoint
:param create: if True an exception is thrown.
"""
if create:
raise Exception("Cannot create a SPARQL Endpoint")
if isinstance(configuration, tuple):
self.query_endpoint = configuration[0]
if len(configuration) > 1:
self.update_endpoint = configuration[1]
else:
self.query_endpoint = configuration
self.update_endpoint = configuration
def _transaction(self) -> List[str]:
if self._edits is None:
self._edits = []
return self._edits
# Transactional interfaces
[docs] def commit(self) -> None:
"""add(), addN(), and remove() are transactional to reduce overhead of many small edits.
Read and update() calls will automatically commit any outstanding edits.
This should behave as expected most of the time, except that alternating writes
and reads can degenerate to the original call-per-triple situation that originally existed.
"""
if self._edits and len(self._edits) > 0:
self._update("\n;\n".join(self._edits))
self._edits = None
[docs] def rollback(self) -> None:
self._edits = None
[docs] def add(
self,
spo: _TripleType,
context: Optional[_ContextType] = None,
quoted: bool = False,
) -> None:
"""Add a triple to the store of triples."""
if not self.update_endpoint:
raise Exception("UpdateEndpoint is not set")
assert not quoted
(subject, predicate, obj) = spo
nts = self.node_to_sparql
triple = "%s %s %s ." % (nts(subject), nts(predicate), nts(obj))
if self._is_contextual(context):
if TYPE_CHECKING:
# _is_contextual will never return true if context is None
assert context is not None
q = "INSERT DATA { GRAPH %s { %s } }" % (nts(context.identifier), triple)
else:
q = "INSERT DATA { %s }" % triple
self._transaction().append(q)
if self.autocommit:
self.commit()
[docs] def addN(self, quads: Iterable[_QuadType]) -> None: # noqa: N802
"""Add a list of quads to the store."""
if not self.update_endpoint:
raise Exception("UpdateEndpoint is not set - call 'open'")
contexts = collections.defaultdict(list)
for subject, predicate, obj, context in quads:
contexts[context].append((subject, predicate, obj))
data: List[str] = []
nts = self.node_to_sparql
for context in contexts:
triples = [
"%s %s %s ." % (nts(subject), nts(predicate), nts(obj))
for subject, predicate, obj in contexts[context]
]
data.append(
"INSERT DATA { GRAPH %s { %s } }\n"
% (nts(context.identifier), "\n".join(triples))
)
self._transaction().extend(data)
if self.autocommit:
self.commit()
# type error: Signature of "remove" incompatible with supertype "Store"
[docs] def remove( # type: ignore[override]
self, spo: _TriplePatternType, context: Optional[_ContextType]
) -> None:
"""Remove a triple from the store"""
if not self.update_endpoint:
raise Exception("UpdateEndpoint is not set - call 'open'")
(subject, predicate, obj) = spo
if not subject:
subject = Variable("S")
if not predicate:
predicate = Variable("P")
if not obj:
obj = Variable("O")
nts = self.node_to_sparql
triple = "%s %s %s ." % (nts(subject), nts(predicate), nts(obj))
if self._is_contextual(context):
if TYPE_CHECKING:
# _is_contextual will never return true if context is None
assert context is not None
cid = nts(context.identifier)
q = "WITH %(graph)s DELETE { %(triple)s } WHERE { %(triple)s }" % {
"graph": cid,
"triple": triple,
}
else:
q = "DELETE { %s } WHERE { %s } " % (triple, triple)
self._transaction().append(q)
if self.autocommit:
self.commit()
[docs] def setTimeout(self, timeout) -> None: # noqa: N802
self._timeout = int(timeout)
def _update(self, update):
self._updates += 1
SPARQLConnector.update(self, update)
# type error: Signature of "update" incompatible with supertype "SPARQLConnector"
# type error: Signature of "update" incompatible with supertype "Store"
[docs] def update( # type: ignore[override]
self,
query: Union[Update, str],
initNs: Dict[str, Any] = {}, # noqa: N803
initBindings: Dict[str, Identifier] = {}, # noqa: N803
queryGraph: Optional[str] = None, # noqa: N803
DEBUG: bool = False, # noqa: N803
):
"""
Perform a SPARQL Update Query against the endpoint,
INSERT, LOAD, DELETE etc.
Setting initNs adds PREFIX declarations to the beginning of
the update. Setting initBindings adds inline VALUEs to the
beginning of every WHERE clause. By the SPARQL grammar, all
operations that support variables (namely INSERT and DELETE)
require a WHERE clause.
Important: initBindings fails if the update contains the
substring 'WHERE {' which does not denote a WHERE clause, e.g.
if it is part of a literal.
.. admonition:: Context-aware query rewriting
- **When:** If context-awareness is enabled and the graph is not the default graph of the store.
- **Why:** To ensure consistency with the :class:`~rdflib.plugins.stores.memory.Memory` store.
The graph must accept "local" SPARQL requests (requests with no GRAPH keyword)
as if it was the default graph.
- **What is done:** These "local" queries are rewritten by this store.
The content of each block of a SPARQL Update operation is wrapped in a GRAPH block
except if the block is empty.
This basically causes INSERT, INSERT DATA, DELETE, DELETE DATA and WHERE to operate
only on the context.
- **Example:** ``"INSERT DATA { <urn:michel> <urn:likes> <urn:pizza> }"`` is converted into
``"INSERT DATA { GRAPH <urn:graph> { <urn:michel> <urn:likes> <urn:pizza> } }"``.
- **Warning:** Queries are presumed to be "local" but this assumption is **not checked**.
For instance, if the query already contains GRAPH blocks, the latter will be wrapped in new GRAPH blocks.
- **Warning:** A simplified grammar is used that should tolerate
extensions of the SPARQL grammar. Still, the process may fail in
uncommon situations and produce invalid output.
"""
if not self.update_endpoint:
raise Exception("Update endpoint is not set!")
self.debug = DEBUG
assert isinstance(query, str)
query = self._inject_prefixes(query, initNs)
if self._is_contextual(queryGraph):
if TYPE_CHECKING:
# _is_contextual will never return true if context is None
assert queryGraph is not None
query = self._insert_named_graph(query, queryGraph)
if initBindings:
# For INSERT and DELETE the WHERE clause is obligatory
# (http://www.w3.org/TR/2013/REC-sparql11-query-20130321/#rModify)
# Other query types do not allow variables and don't
# have a WHERE clause. This also works for updates with
# more than one INSERT/DELETE.
v = list(initBindings)
values = "\nVALUES ( %s )\n{ ( %s ) }\n" % (
" ".join("?" + str(x) for x in v),
" ".join(self.node_to_sparql(initBindings[x]) for x in v),
)
query = self.where_pattern.sub("WHERE { " + values, query)
self._transaction().append(query)
if self.autocommit:
self.commit()
def _insert_named_graph(self, query: str, query_graph: str) -> str:
"""
Inserts GRAPH <query_graph> {} into blocks of SPARQL Update operations
For instance, "INSERT DATA { <urn:michel> <urn:likes> <urn:pizza> }"
is converted into
"INSERT DATA { GRAPH <urn:graph> { <urn:michel> <urn:likes> <urn:pizza> } }"
"""
if isinstance(query_graph, Node):
query_graph = self.node_to_sparql(query_graph)
else:
query_graph = "<%s>" % query_graph
graph_block_open = " GRAPH %s {" % query_graph
graph_block_close = "} "
# SPARQL Update supports the following operations:
# LOAD, CLEAR, DROP, ADD, MOVE, COPY, CREATE, INSERT DATA, DELETE DATA, DELETE/INSERT, DELETE WHERE
# LOAD, CLEAR, DROP, ADD, MOVE, COPY, CREATE do not make much sense in a context.
# INSERT DATA, DELETE DATA, and DELETE WHERE require the contents of their block to be wrapped in a GRAPH <?> { }.
# DELETE/INSERT supports the WITH keyword, which sets the graph to be
# used for all following DELETE/INSERT instruction including the
# non-optional WHERE block. Equivalently, a GRAPH block can be added to
# all blocks.
#
# Strategy employed here: Wrap the contents of every top-level block into a `GRAPH <?> { }`.
level = 0
modified_query = []
pos = 0
for match in self.BLOCK_FINDING_PATTERN.finditer(query):
if match.group("block_start") is not None:
level += 1
if level == 1:
modified_query.append(query[pos : match.end()])
modified_query.append(graph_block_open)
pos = match.end()
elif match.group("block_end") is not None:
if level == 1:
since_previous_pos = query[pos : match.start()]
if modified_query[-1] is graph_block_open and (
since_previous_pos == "" or since_previous_pos.isspace()
):
# In this case, adding graph_block_start and
# graph_block_end results in an empty GRAPH block. Some
# endpoints (e.g. TDB) can not handle this. Therefore
# remove the previously added block_start.
modified_query.pop()
modified_query.append(since_previous_pos)
else:
modified_query.append(since_previous_pos)
modified_query.append(graph_block_close)
pos = match.start()
level -= 1
modified_query.append(query[pos:])
return "".join(modified_query)
[docs] def add_graph(self, graph: Graph) -> None:
if not self.graph_aware:
Store.add_graph(self, graph)
elif graph.identifier != DATASET_DEFAULT_GRAPH_ID:
self.update("CREATE GRAPH %s" % self.node_to_sparql(graph.identifier))
[docs] def remove_graph(self, graph: Graph) -> None:
if not self.graph_aware:
Store.remove_graph(self, graph)
elif graph.identifier == DATASET_DEFAULT_GRAPH_ID:
self.update("DROP DEFAULT")
else:
self.update("DROP GRAPH %s" % self.node_to_sparql(graph.identifier))
[docs] def subjects(
self,
predicate: Optional[_PredicateType] = None,
object: Optional[_ObjectType] = None,
) -> Generator[_SubjectType, None, None]:
"""A generator of subjects with the given predicate and object"""
for t, c in self.triples((None, predicate, object)):
yield t[0]
[docs] def predicates(
self,
subject: Optional[_SubjectType] = None,
object: Optional[_ObjectType] = None,
) -> Generator[_PredicateType, None, None]:
"""A generator of predicates with the given subject and object"""
for t, c in self.triples((subject, None, object)):
yield t[1]
[docs] def objects(
self,
subject: Optional[_SubjectType] = None,
predicate: Optional[_PredicateType] = None,
) -> Generator[_ObjectType, None, None]:
"""A generator of objects with the given subject and predicate"""
for t, c in self.triples((subject, predicate, None)):
yield t[2]
[docs] def subject_predicates(
self, object: Optional[_ObjectType] = None
) -> Generator[Tuple[_SubjectType, _PredicateType], None, None]:
"""A generator of (subject, predicate) tuples for the given object"""
for t, c in self.triples((None, None, object)):
yield t[0], t[1]
[docs] def subject_objects(
self, predicate: Optional[_PredicateType] = None
) -> Generator[Tuple[_SubjectType, _ObjectType], None, None]:
"""A generator of (subject, object) tuples for the given predicate"""
for t, c in self.triples((None, predicate, None)):
yield t[0], t[2]
[docs] def predicate_objects(
self, subject: Optional[_SubjectType] = None
) -> Generator[Tuple[_PredicateType, _ObjectType], None, None]:
"""A generator of (predicate, object) tuples for the given subject"""
for t, c in self.triples((subject, None, None)):
yield t[1], t[2]
__all__ = ["SPARQLUpdateStore", "SPARQLStore"]
