Source code for rdflib.plugins.sparql.results.jsonresults

import json
from typing import IO, Any, Dict, Optional, TextIO, Union

from rdflib.query import Result, ResultException, ResultSerializer, ResultParser
from rdflib import Literal, URIRef, BNode, Variable


"""A Serializer for SPARQL results in JSON:

http://www.w3.org/TR/rdf-sparql-json-res/

Bits and pieces borrowed from:
http://projects.bigasterisk.com/sparqlhttp/

Authors: Drew Perttula, Gunnar Aastrand Grimnes

"""


[docs]class JSONResultParser(ResultParser):
[docs] def parse(self, source, content_type=None): inp = source.read() if isinstance(inp, bytes): inp = inp.decode("utf-8") return JSONResult(json.loads(inp))
[docs]class JSONResultSerializer(ResultSerializer):
[docs] def __init__(self, result): ResultSerializer.__init__(self, result)
[docs] def serialize(self, stream: IO, encoding: str = None): # type: ignore[override] res: Dict[str, Any] = {} if self.result.type == "ASK": res["head"] = {} res["boolean"] = self.result.askAnswer else: # select res["results"] = {} res["head"] = {} res["head"]["vars"] = self.result.vars res["results"]["bindings"] = [ self._bindingToJSON(x) for x in self.result.bindings ] r = json.dumps(res, allow_nan=False, ensure_ascii=False) if encoding is not None: stream.write(r.encode(encoding)) else: stream.write(r)
def _bindingToJSON(self, b): res = {} for var in b: j = termToJSON(self, b[var]) if j is not None: res[var] = termToJSON(self, b[var]) return res
[docs]class JSONResult(Result):
[docs] def __init__(self, json): self.json = json if "boolean" in json: type_ = "ASK" elif "results" in json: type_ = "SELECT" else: raise ResultException("No boolean or results in json!") Result.__init__(self, type_) if type_ == "ASK": self.askAnswer = bool(json["boolean"]) else: self.bindings = self._get_bindings() self.vars = [Variable(x) for x in json["head"]["vars"]]
def _get_bindings(self): ret = [] for row in self.json["results"]["bindings"]: outRow = {} for k, v in row.items(): outRow[Variable(k)] = parseJsonTerm(v) ret.append(outRow) return ret
[docs]def parseJsonTerm(d): """rdflib object (Literal, URIRef, BNode) for the given json-format dict. input is like: { 'type': 'uri', 'value': 'http://famegame.com/2006/01/username' } { 'type': 'literal', 'value': 'drewp' } """ t = d["type"] if t == "uri": return URIRef(d["value"]) elif t == "literal": return Literal(d["value"], datatype=d.get("datatype"), lang=d.get("xml:lang")) elif t == "typed-literal": return Literal(d["value"], datatype=URIRef(d["datatype"])) elif t == "bnode": return BNode(d["value"]) else: raise NotImplementedError("json term type %r" % t)
[docs]def termToJSON(self, term): if isinstance(term, URIRef): return {"type": "uri", "value": str(term)} elif isinstance(term, Literal): r = {"type": "literal", "value": str(term)} if term.datatype is not None: r["datatype"] = str(term.datatype) if term.language is not None: r["xml:lang"] = term.language return r elif isinstance(term, BNode): return {"type": "bnode", "value": str(term)} elif term is None: return None else: raise ResultException("Unknown term type: %s (%s)" % (term, type(term)))