Python: query results I/O

python/docs/sparql.rst

@@ -9,7 +9,6 @@ Variable
 .. autoclass:: pyoxigraph.Variable
     :members:
 
-
 ``SELECT`` solutions
 """"""""""""""""""""
 .. autoclass:: pyoxigraph.QuerySolutions
@@ -17,7 +16,17 @@ Variable
 .. autoclass:: pyoxigraph.QuerySolution
     :members:
 
+``ASK`` results
+"""""""""""""""
+.. autoclass:: pyoxigraph.QueryBoolean
+    :members:
+
 ``CONSTRUCT`` results
 """""""""""""""""""""
 .. autoclass:: pyoxigraph.QueryTriples
     :members:
+
+Query results parsing
+"""""""""""""""""""""
+.. autoclass:: pyoxigraph.parse_query_results
+    :members:

python/src/io.rs

@@ -3,10 +3,11 @@
 use crate::model::{PyQuad, PyTriple};
 use oxigraph::io::{FromReadQuadReader, ParseError, RdfFormat, RdfParser, RdfSerializer};
 use oxigraph::model::QuadRef;
+use oxigraph::sparql::results::QueryResultsFormat;
 use pyo3::exceptions::{PySyntaxError, PyValueError};
+use pyo3::intern;
 use pyo3::prelude::*;
 use pyo3::types::PyBytes;
-use pyo3::{intern, wrap_pyfunction};
 use std::cmp::max;
 use std::error::Error;
 use std::ffi::OsStr;
@@ -14,11 +15,6 @@ use std::fs::File;
 use std::io::{self, BufWriter, Cursor, Read, Write};
 use std::path::{Path, PathBuf};
 
-pub fn add_to_module(module: &PyModule) -> PyResult<()> {
-    module.add_wrapped(wrap_pyfunction!(parse))?;
-    module.add_wrapped(wrap_pyfunction!(serialize))
-}
-
 /// Parses RDF graph and dataset serialization formats.
 ///
 /// It currently supports the following formats:
@@ -63,7 +59,7 @@ pub fn parse(
     py: Python<'_>,
 ) -> PyResult<PyObject> {
     let file_path = input.extract::<PathBuf>().ok();
-    let format = rdf_format(format, file_path.as_deref())?;
+    let format = parse_format(format, file_path.as_deref())?;
     let input = if let Some(file_path) = &file_path {
         PyReadable::from_file(file_path, py).map_err(map_io_err)?
     } else {
@@ -128,40 +124,31 @@ pub fn serialize<'a>(
     format: Option<&str>,
     py: Python<'a>,
 ) -> PyResult<Option<&'a PyBytes>> {
-    let file_path = output.and_then(|output| output.extract::<PathBuf>().ok());
-    let format = rdf_format(format, file_path.as_deref())?;
-    let output = if let Some(output) = output {
-        if let Some(file_path) = &file_path {
-            PyWritable::from_file(file_path, py).map_err(map_io_err)?
-        } else {
-            PyWritable::from_data(output)
-        }
-    } else {
-        PyWritable::Bytes(Vec::new())
-    };
-    let mut writer = RdfSerializer::from_format(format).serialize_to_write(BufWriter::new(output));
-    for i in input.iter()? {
-        let i = i?;
-        if let Ok(triple) = i.extract::<PyRef<PyTriple>>() {
-            writer.write_triple(&*triple)
-        } else {
-            let quad = i.extract::<PyRef<PyQuad>>()?;
-            let quad = QuadRef::from(&*quad);
-            if !quad.graph_name.is_default_graph() && !format.supports_datasets() {
-                return Err(PyValueError::new_err(
-                    "The {format} format does not support named graphs",
-                ));
+    PyWritable::do_write(
+        |output, format| {
+            let mut writer = RdfSerializer::from_format(format).serialize_to_write(output);
+            for i in input.iter()? {
+                let i = i?;
+                if let Ok(triple) = i.extract::<PyRef<PyTriple>>() {
+                    writer.write_triple(&*triple)
+                } else {
+                    let quad = i.extract::<PyRef<PyQuad>>()?;
+                    let quad = QuadRef::from(&*quad);
+                    if !quad.graph_name.is_default_graph() && !format.supports_datasets() {
+                        return Err(PyValueError::new_err(
+                            "The {format} format does not support named graphs",
+                        ));
+                    }
+                    writer.write_quad(quad)
+                }
+                .map_err(map_io_err)?;
             }
-            writer.write_quad(quad)
-        }
-        .map_err(map_io_err)?;
-    }
-    writer
-        .finish()
-        .map_err(map_io_err)?
-        .into_inner()
-        .map_err(|e| map_io_err(e.into_error()))?
-        .close(py)
+            writer.finish().map_err(map_io_err)
+        },
+        output,
+        format,
+        py,
+    )
 }
 
 #[pyclass(name = "QuadReader", module = "pyoxigraph")]
@@ -228,15 +215,33 @@ pub enum PyWritable {
 }
 
 impl PyWritable {
-    pub fn from_file(file: &Path, py: Python<'_>) -> io::Result<Self> {
-        Ok(Self::File(py.allow_threads(|| File::create(file))?))
-    }
-
-    pub fn from_data(data: &PyAny) -> Self {
-        Self::Io(PyIo(data.into()))
+    pub fn do_write<'a, F: Format>(
+        write: impl FnOnce(BufWriter<Self>, F) -> PyResult<BufWriter<Self>>,
+        output: Option<&PyAny>,
+        format: Option<&str>,
+        py: Python<'a>,
+    ) -> PyResult<Option<&'a PyBytes>> {
+        let file_path = output.and_then(|output| output.extract::<PathBuf>().ok());
+        let format = parse_format::<F>(format, file_path.as_deref())?;
+        let output = if let Some(output) = output {
+            if let Some(file_path) = &file_path {
+                Self::File(
+                    py.allow_threads(|| File::create(file_path))
+                        .map_err(map_io_err)?,
+                )
+            } else {
+                Self::Io(PyIo(output.into()))
+            }
+        } else {
+            PyWritable::Bytes(Vec::new())
+        };
+        let writer = write(BufWriter::new(output), format)?;
+        py.allow_threads(|| writer.into_inner())
+            .map_err(|e| map_io_err(e.into_error()))?
+            .close(py)
     }
 
-    pub fn close(self, py: Python<'_>) -> PyResult<Option<&PyBytes>> {
+    fn close(self, py: Python<'_>) -> PyResult<Option<&PyBytes>> {
         match self {
             Self::Bytes(bytes) => Ok(Some(PyBytes::new(py, &bytes))),
             Self::File(mut file) => {
@@ -320,7 +325,32 @@ impl Write for PyIo {
     }
 }
 
-pub fn rdf_format(format: Option<&str>, path: Option<&Path>) -> PyResult<RdfFormat> {
+pub trait Format: Sized {
+    fn from_media_type(media_type: &str) -> Option<Self>;
+    fn from_extension(extension: &str) -> Option<Self>;
+}
+
+impl Format for RdfFormat {
+    fn from_media_type(media_type: &str) -> Option<Self> {
+        Self::from_media_type(media_type)
+    }
+
+    fn from_extension(extension: &str) -> Option<Self> {
+        Self::from_extension(extension)
+    }
+}
+
+impl Format for QueryResultsFormat {
+    fn from_media_type(media_type: &str) -> Option<Self> {
+        Self::from_media_type(media_type)
+    }
+
+    fn from_extension(extension: &str) -> Option<Self> {
+        Self::from_extension(extension)
+    }
+}
+
+pub fn parse_format<F: Format>(format: Option<&str>, path: Option<&Path>) -> PyResult<F> {
     let format = if let Some(format) = format {
         format
     } else if let Some(path) = path {
@@ -338,11 +368,11 @@ pub fn rdf_format(format: Option<&str>, path: Option<&Path>) -> PyResult<RdfForm
         ));
     };
     if format.contains('/') {
-        RdfFormat::from_media_type(format).ok_or_else(|| {
+        F::from_media_type(format).ok_or_else(|| {
             PyValueError::new_err(format!("Not supported RDF format media type: {format}"))
         })
     } else {
-        RdfFormat::from_extension(format).ok_or_else(|| {
+        F::from_extension(format).ok_or_else(|| {
             PyValueError::new_err(format!("Not supported RDF format extension: {format}"))
         })
     }
@@ -404,7 +434,7 @@ pub fn map_parse_error(error: ParseError, file_path: Option<PathBuf>) -> PyErr {
 ///
 /// Code from pyo3: https://github.com/PyO3/pyo3/blob/a67180c8a42a0bc0fdc45b651b62c0644130cf47/src/python.rs#L366
 #[allow(unsafe_code)]
-pub fn allow_threads_unsafe<T>(f: impl FnOnce() -> T) -> T {
+pub fn allow_threads_unsafe<T>(_py: Python<'_>, f: impl FnOnce() -> T) -> T {
     struct RestoreGuard {
         tstate: *mut pyo3::ffi::PyThreadState,
     }

python/src/lib.rs

@@ -10,6 +10,7 @@ mod model;
 mod sparql;
 mod store;
 
+use crate::io::*;
 use crate::model::*;
 use crate::sparql::*;
 use crate::store::*;
@@ -34,5 +35,8 @@ fn pyoxigraph(_py: Python<'_>, module: &PyModule) -> PyResult<()> {
     module.add_class::<PyQuerySolution>()?;
     module.add_class::<PyQueryBoolean>()?;
     module.add_class::<PyQueryTriples>()?;
-    io::add_to_module(module)
+    module.add_wrapped(wrap_pyfunction!(parse))?;
+    module.add_wrapped(wrap_pyfunction!(parse_query_results))?;
+    module.add_wrapped(wrap_pyfunction!(serialize))?;
+    Ok(())
 }

python/src/sparql.rs

@@ -1,14 +1,23 @@
-use crate::io::{allow_threads_unsafe, map_io_err, map_parse_error};
-use crate::map_storage_error;
+use crate::io::*;
 use crate::model::*;
+use crate::store::map_storage_error;
+use oxigraph::io::RdfSerializer;
 use oxigraph::model::Term;
-use oxigraph::sparql::*;
+use oxigraph::sparql::results::{
+    ParseError, QueryResultsParser, QueryResultsReader, QueryResultsSerializer, SolutionsReader,
+};
+use oxigraph::sparql::{
+    EvaluationError, Query, QueryResults, QuerySolution, QuerySolutionIter, QueryTripleIter,
+    Variable,
+};
 use pyo3::basic::CompareOp;
 use pyo3::exceptions::{
     PyNotImplementedError, PyRuntimeError, PySyntaxError, PyTypeError, PyValueError,
 };
-
 use pyo3::prelude::*;
+use pyo3::types::PyBytes;
+use std::io::BufReader;
+use std::path::PathBuf;
 use std::vec::IntoIter;
 
 pub fn parse_query(
@@ -17,8 +26,9 @@ pub fn parse_query(
     use_default_graph_as_union: bool,
     default_graph: Option<&PyAny>,
     named_graphs: Option<&PyAny>,
+    py: Python<'_>,
 ) -> PyResult<Query> {
-    let mut query = allow_threads_unsafe(|| Query::parse(query, base_iri))
+    let mut query = allow_threads_unsafe(py, || Query::parse(query, base_iri))
         .map_err(|e| map_evaluation_error(e.into()))?;
 
     if use_default_graph_as_union && default_graph.is_some() {
@@ -63,7 +73,10 @@ pub fn parse_query(
 
 pub fn query_results_to_python(py: Python<'_>, results: QueryResults) -> PyObject {
     match results {
-        QueryResults::Solutions(inner) => PyQuerySolutions { inner }.into_py(py),
+        QueryResults::Solutions(inner) => PyQuerySolutions {
+            inner: PyQuerySolutionsVariant::Query(inner),
+        }
+        .into_py(py),
         QueryResults::Graph(inner) => PyQueryTriples { inner }.into_py(py),
         QueryResults::Boolean(inner) => PyQueryBoolean { inner }.into_py(py),
     }
@@ -172,7 +185,11 @@ impl SolutionValueIter {
 /// [<QuerySolution s=<NamedNode value=http://example.com>>]
 #[pyclass(unsendable, name = "QuerySolutions", module = "pyoxigraph")]
 pub struct PyQuerySolutions {
-    inner: QuerySolutionIter,
+    inner: PyQuerySolutionsVariant,
+}
+enum PyQuerySolutionsVariant {
+    Query(QuerySolutionIter),
+    Reader(SolutionsReader<BufReader<PyReadable>>),
 }
 
 #[pymethods]
@@ -185,22 +202,99 @@ impl PyQuerySolutions {
     /// [<Variable value=s>]
     #[getter]
     fn variables(&self) -> Vec<PyVariable> {
-        self.inner
-            .variables()
-            .iter()
-            .map(|v| v.clone().into())
-            .collect()
+        match &self.inner {
+            PyQuerySolutionsVariant::Query(inner) => {
+                inner.variables().iter().map(|v| v.clone().into()).collect()
+            }
+            PyQuerySolutionsVariant::Reader(inner) => {
+                inner.variables().iter().map(|v| v.clone().into()).collect()
+            }
+        }
+    }
+
+    /// Writes the query results into a file.
+    ///
+    /// It currently supports the following formats:
+    ///
+    /// * `XML <https://www.w3.org/TR/rdf-sparql-XMLres/>`_ (``application/sparql-results+xml`` or ``srx``)
+    /// * `JSON <https://www.w3.org/TR/sparql11-results-json/>`_ (``application/sparql-results+json`` or ``srj``)
+    /// * `CSV <https://www.w3.org/TR/sparql11-results-csv-tsv/>`_ (``text/csv`` or ``csv``)
+    /// * `TSV <https://www.w3.org/TR/sparql11-results-csv-tsv/>`_ (``text/tab-separated-values`` or ``tsv``)
+    ///
+    /// It supports also some media type and extension aliases.
+    /// For example, ``application/json`` could also be used for `JSON <https://www.w3.org/TR/sparql11-results-json/>`_.
+    ///
+    /// :param output: The binary I/O object or file path to write to. For example, it could be a file path as a string or a file writer opened in binary mode with ``open('my_file.ttl', 'wb')``. If :py:const:`None`, a :py:func:`bytes` buffer is returned with the serialized content.
+    /// :type output: io(bytes) or str or pathlib.Path or None, optional
+    /// :param format: the format of the query results serialization using a media type like ``text/csv`` or an extension like `csv`. If :py:const:`None`, the format is guessed from the file name extension.
+    /// :type format: str or None, optional
+    /// :rtype: bytes or None
+    /// :raises ValueError: if the format is not supported.
+    /// :raises OSError: if an error happens during a file writing.
+    ///
+    /// >>> store = Store()
+    /// >>> store.add(Quad(NamedNode('http://example.com'), NamedNode('http://example.com/p'), Literal('1')))
+    /// >>> results = store.query("SELECT ?s ?p ?o WHERE { ?s ?p ?o }")
+    /// >>> results.serialize(format="json")
+    /// b'{"head":{"vars":["s","p","o"]},"results":{"bindings":[{"s":{"type":"uri","value":"http://example.com"},"p":{"type":"uri","value":"http://example.com/p"},"o":{"type":"literal","value":"1"}}]}}'
+    #[pyo3(signature = (output = None, /, format = None))]
+    fn serialize<'a>(
+        &mut self,
+        output: Option<&PyAny>,
+        format: Option<&str>,
+        py: Python<'a>,
+    ) -> PyResult<Option<&'a PyBytes>> {
+        PyWritable::do_write(
+            |output, format| {
+                let mut writer = QueryResultsSerializer::from_format(format)
+                    .solutions_writer(
+                        output,
+                        match &self.inner {
+                            PyQuerySolutionsVariant::Query(inner) => inner.variables().to_vec(),
+                            PyQuerySolutionsVariant::Reader(inner) => inner.variables().to_vec(),
+                        },
+                    )
+                    .map_err(map_io_err)?;
+                match &mut self.inner {
+                    PyQuerySolutionsVariant::Query(inner) => {
+                        for solution in inner {
+                            writer
+                                .write(&solution.map_err(map_evaluation_error)?)
+                                .map_err(map_io_err)?;
+                        }
+                    }
+                    PyQuerySolutionsVariant::Reader(inner) => {
+                        for solution in inner {
+                            writer
+                                .write(&solution.map_err(map_query_results_parse_error)?)
+                                .map_err(map_io_err)?;
+                        }
+                    }
+                }
+
+                writer.finish().map_err(map_io_err)
+            },
+            output,
+            format,
+            py,
+        )
     }
 
     fn __iter__(slf: PyRef<'_, Self>) -> PyRef<Self> {
         slf
     }
 
-    fn __next__(&mut self) -> PyResult<Option<PyQuerySolution>> {
-        Ok(allow_threads_unsafe(|| self.inner.next())
-            .transpose()
-            .map_err(map_evaluation_error)?
-            .map(move |inner| PyQuerySolution { inner }))
+    fn __next__(&mut self, py: Python<'_>) -> PyResult<Option<PyQuerySolution>> {
+        Ok(match &mut self.inner {
+            PyQuerySolutionsVariant::Query(inner) => allow_threads_unsafe(py, || {
+                inner.next().transpose().map_err(map_evaluation_error)
+            }),
+            PyQuerySolutionsVariant::Reader(inner) => inner
+                .next()
+                .transpose()
+                .map_err(map_query_results_parse_error),
+        }?
+        .map(move |inner| PyQuerySolution { inner }))
     }
 }
 
@@ -219,6 +313,52 @@ pub struct PyQueryBoolean {
 
 #[pymethods]
 impl PyQueryBoolean {
+    /// Writes the query results into a file.
+    ///
+    /// It currently supports the following formats:
+    ///
+    /// * `XML <https://www.w3.org/TR/rdf-sparql-XMLres/>`_ (``application/sparql-results+xml`` or ``srx``)
+    /// * `JSON <https://www.w3.org/TR/sparql11-results-json/>`_ (``application/sparql-results+json`` or ``srj``)
+    /// * `CSV <https://www.w3.org/TR/sparql11-results-csv-tsv/>`_ (``text/csv`` or ``csv``)
+    /// * `TSV <https://www.w3.org/TR/sparql11-results-csv-tsv/>`_ (``text/tab-separated-values`` or ``tsv``)
+    ///
+    /// It supports also some media type and extension aliases.
+    /// For example, ``application/json`` could also be used for `JSON <https://www.w3.org/TR/sparql11-results-json/>`_.
+    ///
+    /// :param output: The binary I/O object or file path to write to. For example, it could be a file path as a string or a file writer opened in binary mode with ``open('my_file.ttl', 'wb')``. If :py:const:`None`, a :py:func:`bytes` buffer is returned with the serialized content.
+    /// :type output: io(bytes) or str or pathlib.Path or None, optional
+    /// :param format: the format of the query results serialization using a media type like ``text/csv`` or an extension like `csv`. If :py:const:`None`, the format is guessed from the file name extension.
+    /// :type format: str or None, optional
+    /// :rtype: bytes or None
+    /// :raises ValueError: if the format is not supported.
+    /// :raises OSError: if an error happens during a file writing.
+    ///
+    /// >>> store = Store()
+    /// >>> store.add(Quad(NamedNode('http://example.com'), NamedNode('http://example.com/p'), Literal('1')))
+    /// >>> results = store.query("ASK { ?s ?p ?o }")
+    /// >>> results.serialize(format="json")
+    /// b'{"head":{},"boolean":true}'
+    #[pyo3(signature = (output = None, /, format = None))]
+    fn serialize<'a>(
+        &mut self,
+        output: Option<&PyAny>,
+        format: Option<&str>,
+        py: Python<'a>,
+    ) -> PyResult<Option<&'a PyBytes>> {
+        PyWritable::do_write(
+            |output, format| {
+                py.allow_threads(|| {
+                    QueryResultsSerializer::from_format(format)
+                        .write_boolean_result(output, self.inner)
+                        .map_err(map_io_err)
+                })
+            },
+            output,
+            format,
+            py,
+        )
+    }
+
     fn __bool__(&self) -> bool {
         self.inner
     }
@@ -249,29 +389,129 @@ pub struct PyQueryTriples {
 
 #[pymethods]
 impl PyQueryTriples {
+    /// Writes the query results into a file.
+    ///
+    /// It currently supports the following formats:
+    ///
+    /// * `N-Triples <https://www.w3.org/TR/n-triples/>`_ (``application/n-triples`` or ``nt``)
+    /// * `N-Quads <https://www.w3.org/TR/n-quads/>`_ (``application/n-quads`` or ``nq``)
+    /// * `Turtle <https://www.w3.org/TR/turtle/>`_ (``text/turtle`` or ``ttl``)
+    /// * `TriG <https://www.w3.org/TR/trig/>`_ (``application/trig`` or ``trig``)
+    /// * `N3 <https://w3c.github.io/N3/spec/>`_ (``text/n3`` or ``n3``)
+    /// * `RDF/XML <https://www.w3.org/TR/rdf-syntax-grammar/>`_ (``application/rdf+xml`` or ``rdf``)
+    ///
+    /// It supports also some media type and extension aliases.
+    /// For example, ``application/turtle`` could also be used for `Turtle <https://www.w3.org/TR/turtle/>`_
+    /// and ``application/xml`` or ``xml`` for `RDF/XML <https://www.w3.org/TR/rdf-syntax-grammar/>`_.
+    ///
+    /// :param output: The binary I/O object or file path to write to. For example, it could be a file path as a string or a file writer opened in binary mode with ``open('my_file.ttl', 'wb')``. If :py:const:`None`, a :py:func:`bytes` buffer is returned with the serialized content.
+    /// :type output: io(bytes) or str or pathlib.Path or None, optional
+    /// :param format: the format of the RDF serialization using a media type like ``text/turtle`` or an extension like `ttl`. If :py:const:`None`, the format is guessed from the file name extension.
+    /// :type format: str or None, optional
+    /// :rtype: bytes or None
+    /// :raises ValueError: if the format is not supported.
+    /// :raises OSError: if an error happens during a file writing.
+    ///
+    /// >>> store = Store()
+    /// >>> store.add(Quad(NamedNode('http://example.com'), NamedNode('http://example.com/p'), Literal('1')))
+    /// >>> results = store.query("CONSTRUCT { ?s ?p ?o } WHERE { ?s ?p ?o }")
+    /// >>> results.serialize(format="nt")
+    /// b'<http://example.com> <http://example.com/p> "1" .\n'
+    #[pyo3(signature = (output = None, /, format = None))]
+    fn serialize<'a>(
+        &mut self,
+        output: Option<&PyAny>,
+        format: Option<&str>,
+        py: Python<'a>,
+    ) -> PyResult<Option<&'a PyBytes>> {
+        PyWritable::do_write(
+            |output, format| {
+                let mut writer = RdfSerializer::from_format(format).serialize_to_write(output);
+                for triple in &mut self.inner {
+                    writer
+                        .write_triple(&triple.map_err(map_evaluation_error)?)
+                        .map_err(map_io_err)?;
+                }
+                writer.finish().map_err(map_io_err)
+            },
+            output,
+            format,
+            py,
+        )
+    }
+
     fn __iter__(slf: PyRef<'_, Self>) -> PyRef<Self> {
         slf
     }
 
-    fn __next__(&mut self) -> PyResult<Option<PyTriple>> {
-        Ok(allow_threads_unsafe(|| self.inner.next())
+    fn __next__(&mut self, py: Python<'_>) -> PyResult<Option<PyTriple>> {
+        Ok(allow_threads_unsafe(py, || self.inner.next())
             .transpose()
             .map_err(map_evaluation_error)?
             .map(Into::into))
     }
 }
 
+/// Parses SPARQL query results.
+///
+/// It currently supports the following formats:
+///
+/// * `XML <https://www.w3.org/TR/rdf-sparql-XMLres/>`_ (``application/sparql-results+xml`` or ``srx``)
+/// * `JSON <https://www.w3.org/TR/sparql11-results-json/>`_ (``application/sparql-results+json`` or ``srj``)
+/// * `CSV <https://www.w3.org/TR/sparql11-results-csv-tsv/>`_ (``text/csv`` or ``csv``)
+/// * `TSV <https://www.w3.org/TR/sparql11-results-csv-tsv/>`_ (``text/tab-separated-values`` or ``tsv``)
+///
+/// It supports also some media type and extension aliases.
+/// For example, ``application/json`` could also be used for `JSON <https://www.w3.org/TR/sparql11-results-json/>`_.
+///
+/// :param input: The I/O object or file path to read from. For example, it could be a file path as a string or a file reader opened in binary mode with ``open('my_file.ttl', 'rb')``.
+/// :type input: io(bytes) or io(str) or str or pathlib.Path
+/// :param format: the format of the RDF serialization using a media type like ``text/turtle`` or an extension like `ttl`. If :py:const:`None`, the format is guessed from the file name extension.
+/// :type format: str or None, optional
+/// :return: an iterator of :py:class:`QuerySolution` or a :py:func:`bool`.
+/// :rtype: QuerySolutions or QueryBoolean
+/// :raises ValueError: if the format is not supported.
+/// :raises SyntaxError: if the provided data is invalid.
+///
+/// >>> input = io.BytesIO(b'?s\t?p\t?o\n<http://example.com/s>\t<http://example.com/s>\t1\n')
+/// >>> list(parse_query_results(input, "text/tsv"))
+/// [<QuerySolution s=<NamedNode value=http://example.com/s> p=<NamedNode value=http://example.com/s> o=<Literal value=1 datatype=<NamedNode value=http://www.w3.org/2001/XMLSchema#integer>>>]
+///
+/// >>> input = io.BytesIO(b'{"head":{},"boolean":true}')
+/// >>> parse_query_results(input, "application/sparql-results+json")
+/// <QueryBoolean true>
+#[pyfunction]
+#[pyo3(signature = (input, /, format = None))]
+pub fn parse_query_results(
+    input: &PyAny,
+    format: Option<&str>,
+    py: Python<'_>,
+) -> PyResult<PyObject> {
+    let file_path = input.extract::<PathBuf>().ok();
+    let format = parse_format(format, file_path.as_deref())?;
+    let input = if let Some(file_path) = &file_path {
+        PyReadable::from_file(file_path, py).map_err(map_io_err)?
+    } else {
+        PyReadable::from_data(input)
+    };
+    let results = QueryResultsParser::from_format(format)
+        .read_results(BufReader::new(input))
+        .map_err(map_query_results_parse_error)?;
+    Ok(match results {
+        QueryResultsReader::Solutions(inner) => PyQuerySolutions {
+            inner: PyQuerySolutionsVariant::Reader(inner),
+        }
+        .into_py(py),
+        QueryResultsReader::Boolean(inner) => PyQueryBoolean { inner }.into_py(py),
+    })
+}
+
 pub fn map_evaluation_error(error: EvaluationError) -> PyErr {
     match error {
         EvaluationError::Parsing(error) => PySyntaxError::new_err(error.to_string()),
         EvaluationError::Storage(error) => map_storage_error(error),
         EvaluationError::GraphParsing(error) => map_parse_error(error, None),
-        EvaluationError::ResultsParsing(error) => match error {
-            oxigraph::sparql::results::ParseError::Syntax(error) => {
-                PySyntaxError::new_err(error.to_string())
-            }
-            oxigraph::sparql::results::ParseError::Io(error) => map_io_err(error),
-        },
+        EvaluationError::ResultsParsing(error) => map_query_results_parse_error(error),
         EvaluationError::ResultsSerialization(error) => map_io_err(error),
         EvaluationError::Service(error) => match error.downcast() {
             Ok(error) => map_io_err(*error),
@@ -280,3 +520,10 @@ pub fn map_evaluation_error(error: EvaluationError) -> PyErr {
         _ => PyRuntimeError::new_err(error.to_string()),
     }
 }
+
+pub fn map_query_results_parse_error(error: ParseError) -> PyErr {
+    match error {
+        ParseError::Syntax(error) => PySyntaxError::new_err(error.to_string()),
+        ParseError::Io(error) => map_io_err(error),
+    }
+}

python/src/store.rs

@@ -1,17 +1,17 @@
 #![allow(clippy::needless_option_as_deref)]
 
 use crate::io::{
-    allow_threads_unsafe, map_io_err, map_parse_error, rdf_format, PyReadable, PyWritable,
+    allow_threads_unsafe, map_io_err, map_parse_error, parse_format, PyReadable, PyWritable,
 };
 use crate::model::*;
 use crate::sparql::*;
+use oxigraph::io::RdfFormat;
 use oxigraph::model::{GraphName, GraphNameRef};
 use oxigraph::sparql::Update;
 use oxigraph::store::{self, LoaderError, SerializerError, StorageError, Store};
 use pyo3::exceptions::{PyRuntimeError, PyValueError};
 use pyo3::prelude::*;
 use pyo3::types::PyBytes;
-use std::io::BufWriter;
 use std::path::PathBuf;
 
 /// RDF store.
@@ -251,7 +251,7 @@ impl PyStore {
     /// :type default_graph: NamedNode or BlankNode or DefaultGraph or list(NamedNode or BlankNode or DefaultGraph) or None, optional
     /// :param named_graphs: list of the named graphs that could be used in SPARQL `GRAPH` clause. By default, all the store named graphs are available.
     /// :type named_graphs: list(NamedNode or BlankNode) or None, optional
-    /// :return: a :py:class:`QueryBoolean` for ``ASK`` queries, an iterator of :py:class:`Triple` for ``CONSTRUCT`` and ``DESCRIBE`` queries and an iterator of :py:class:`QuerySolution` for ``SELECT`` queries.
+    /// :return: a :py:func:`bool` for ``ASK`` queries, an iterator of :py:class:`Triple` for ``CONSTRUCT`` and ``DESCRIBE`` queries and an iterator of :py:class:`QuerySolution` for ``SELECT`` queries.
     /// :rtype: QuerySolutions or QueryBoolean or QueryTriples
     /// :raises SyntaxError: if the provided query is invalid.
     /// :raises OSError: if an error happens while reading the store.
@@ -292,9 +292,10 @@ impl PyStore {
             use_default_graph_as_union,
             default_graph,
             named_graphs,
+            py,
         )?;
         let results =
-            allow_threads_unsafe(|| self.inner.query(query)).map_err(map_evaluation_error)?;
+            allow_threads_unsafe(py, || self.inner.query(query)).map_err(map_evaluation_error)?;
         Ok(query_results_to_python(py, results))
     }
 
@@ -393,7 +394,7 @@ impl PyStore {
             None
         };
         let file_path = input.extract::<PathBuf>().ok();
-        let format = rdf_format(format, file_path.as_deref())?;
+        let format = parse_format::<RdfFormat>(format, file_path.as_deref())?;
         let input = if let Some(file_path) = &file_path {
             PyReadable::from_file(file_path, py).map_err(map_io_err)?
         } else {
@@ -462,7 +463,7 @@ impl PyStore {
             None
         };
         let file_path = input.extract::<PathBuf>().ok();
-        let format = rdf_format(format, file_path.as_deref())?;
+        let format = parse_format::<RdfFormat>(format, file_path.as_deref())?;
         let input = if let Some(file_path) = &file_path {
             PyReadable::from_file(file_path, py).map_err(map_io_err)?
         } else {
@@ -505,7 +506,7 @@ impl PyStore {
     /// :type from_graph: NamedNode or BlankNode or DefaultGraph or None, optional
     /// :rtype: bytes or None
     /// :raises ValueError: if the format is not supported or the `from_graph` parameter is not given with a syntax not supporting named graphs.
-    /// :raises OSError: if an error happens during a quad lookup
+    /// :raises OSError: if an error happens during a quad lookup or file writing.
     ///
     /// >>> store = Store()
     /// >>> store.add(Quad(NamedNode('http://example.com'), NamedNode('http://example.com/p'), Literal('1')))
@@ -531,29 +532,21 @@ impl PyStore {
         } else {
             None
         };
-        let file_path = output.and_then(|output| output.extract::<PathBuf>().ok());
-        let format = rdf_format(format, file_path.as_deref())?;
-        let output = if let Some(output) = output {
-            if let Some(file_path) = &file_path {
-                PyWritable::from_file(file_path, py).map_err(map_io_err)?
-            } else {
-                PyWritable::from_data(output)
-            }
-        } else {
-            PyWritable::Bytes(Vec::new())
-        };
-        py.allow_threads(|| {
-            let output = BufWriter::new(output);
-            if let Some(from_graph_name) = &from_graph_name {
-                self.inner.dump_graph(output, format, from_graph_name)
-            } else {
-                self.inner.dump_dataset(output, format)
-            }
-            .map_err(map_serializer_error)?
-            .into_inner()
-            .map_err(|e| map_io_err(e.into_error()))
-        })?
-        .close(py)
+        PyWritable::do_write::<RdfFormat>(
+            |output, format| {
+                py.allow_threads(|| {
+                    if let Some(from_graph_name) = &from_graph_name {
+                        self.inner.dump_graph(output, format, from_graph_name)
+                    } else {
+                        self.inner.dump_dataset(output, format)
+                    }
+                    .map_err(map_serializer_error)
+                })
+            },
+            output,
+            format,
+            py,
+        )
     }
 
     /// Returns an iterator over all the store named graphs.

python/tests/test_io.py

@@ -3,7 +3,16 @@ import unittest
 from io import BytesIO, StringIO, UnsupportedOperation
 from tempfile import NamedTemporaryFile, TemporaryFile
 
-from pyoxigraph import Literal, NamedNode, Quad, parse, serialize
+from pyoxigraph import (
+    Literal,
+    NamedNode,
+    Quad,
+    QueryBoolean,
+    QuerySolutions,
+    parse,
+    parse_query_results,
+    serialize,
+)
 
 EXAMPLE_TRIPLE = Quad(
     NamedNode("http://example.com/foo"),
@@ -131,7 +140,7 @@ class TestParse(unittest.TestCase):
 class TestSerialize(unittest.TestCase):
     def test_serialize_to_bytes(self) -> None:
         self.assertEqual(
-            serialize([EXAMPLE_TRIPLE.triple], None, "text/turtle").decode(),
+            (serialize([EXAMPLE_TRIPLE.triple], None, "text/turtle") or b"").decode(),
             '<http://example.com/foo> <http://example.com/p> "éù" .\n',
         )
 
@@ -162,3 +171,37 @@ class TestSerialize(unittest.TestCase):
             output.getvalue(),
             b'<http://example.com/g> {\n\t<http://example.com/foo> <http://example.com/p> "1" .\n}\n',
         )
+
+
+class TestParseQuerySolutions(unittest.TestCase):
+    def test_parse_file(self) -> None:
+        with NamedTemporaryFile(suffix=".tsv") as fp:
+            fp.write(
+                b'?s\t?p\t?o\n<http://example.com/s>\t<http://example.com/s>\t"1"\n'
+            )
+            fp.flush()
+            r = parse_query_results(fp.name)
+            self.assertIsInstance(r, QuerySolutions)
+            results = list(r)  # type: ignore[arg-type]
+            self.assertEqual(results[0]["s"], NamedNode("http://example.com/s"))
+            self.assertEqual(results[0][2], Literal("1"))
+
+    def test_parse_not_existing_file(self) -> None:
+        with self.assertRaises(IOError) as _:
+            parse_query_results(
+                "/tmp/not-existing-oxigraph-file.ttl", "application/json"
+            )
+
+    def test_parse_str_io(self) -> None:
+        result = parse_query_results(StringIO("true"), "tsv")
+        self.assertIsInstance(result, QueryBoolean)
+        self.assertTrue(result)
+
+    def test_parse_bytes_io(self) -> None:
+        result = parse_query_results(BytesIO(b"false"), "tsv")
+        self.assertIsInstance(result, QueryBoolean)
+        self.assertFalse(result)
+
+    def test_parse_io_error(self) -> None:
+        with self.assertRaises(UnsupportedOperation) as _, TemporaryFile("wb") as fp:
+            parse_query_results(fp, "srx")

python/tests/test_store.py

@@ -189,6 +189,39 @@ class TestStore(unittest.TestCase):
         )
         self.assertEqual(len(list(results)), 2)
 
+    def test_select_query_dump(self) -> None:
+        store = Store()
+        store.add(Quad(foo, bar, baz))
+        results = store.query("SELECT ?s WHERE { ?s ?p ?o }")
+        output = BytesIO()
+        results.serialize(output, "csv")
+        self.assertEqual(
+            output.getvalue().decode(),
+            "s\r\nhttp://foo\r\n",
+        )
+
+    def test_ask_query_dump(self) -> None:
+        store = Store()
+        store.add(Quad(foo, bar, baz))
+        results = store.query("ASK { ?s ?p ?o }")
+        output = BytesIO()
+        results.serialize(output, "csv")
+        self.assertEqual(
+            output.getvalue().decode(),
+            "true",
+        )
+
+    def test_construct_query_dump(self) -> None:
+        store = Store()
+        store.add(Quad(foo, bar, baz))
+        results = store.query("CONSTRUCT WHERE { ?s ?p ?o }")
+        output = BytesIO()
+        results.serialize(output, "nt")
+        self.assertEqual(
+            output.getvalue().decode(),
+            "<http://foo> <http://bar> <http://baz> .\n",
+        )
+
     def test_update_insert_data(self) -> None:
         store = Store()
         store.update("INSERT DATA { <http://foo> <http://foo> <http://foo> }")