nautilus_core/python/
serialization.rs

1// -------------------------------------------------------------------------------------------------
2//  Copyright (C) 2015-2026 Nautech Systems Pty Ltd. All rights reserved.
3//  https://nautechsystems.io
4//
5//  Licensed under the GNU Lesser General Public License Version 3.0 (the "License");
6//  You may not use this file except in compliance with the License.
7//  You may obtain a copy of the License at https://www.gnu.org/licenses/lgpl-3.0.en.html
8//
9//  Unless required by applicable law or agreed to in writing, software
10//  distributed under the License is distributed on an "AS IS" BASIS,
11//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12//  See the License for the specific language governing permissions and
13//  limitations under the License.
14// -------------------------------------------------------------------------------------------------
15
16//! (De)serialization utilities bridging Rust ↔︎ Python types.
17
18use std::{
19    collections::HashMap,
20    hash::{BuildHasher, Hash},
21};
22
23use indexmap::IndexMap;
24use pyo3::{
25    conversion::{FromPyObjectOwned, IntoPyObject},
26    prelude::*,
27    types::{PyAny, PyDict},
28};
29use serde::{Serialize, de::DeserializeOwned};
30
31use crate::python::to_pyvalue_err;
32
33/// Convert a Python dictionary to a Rust type that implements `DeserializeOwned`.
34///
35/// # Errors
36///
37/// Returns an error if:
38/// - The Python dictionary cannot be serialized to JSON.
39/// - The JSON string cannot be deserialized to type `T`.
40/// - The Python `json` module fails to import or execute.
41pub fn from_dict_pyo3<T>(py: Python<'_>, values: Py<PyDict>) -> Result<T, PyErr>
42where
43    T: DeserializeOwned,
44{
45    let values = values.into_any();
46    from_pyobject_pyo3(py, values.bind(py))
47}
48
49/// Convert a Python object to a Rust type that implements `DeserializeOwned`.
50///
51/// # Errors
52///
53/// Returns an error if:
54/// - The Python object cannot be serialized to JSON.
55/// - The JSON string cannot be deserialized to type `T`.
56/// - The Python `json` module fails to import or execute.
57pub fn from_pyobject_pyo3<T>(py: Python<'_>, value: &Bound<'_, PyAny>) -> Result<T, PyErr>
58where
59    T: DeserializeOwned,
60{
61    // `ensure_ascii=False` keeps non-ASCII characters as raw UTF-8 in the JSON output.
62    // Without this, `\uXXXX` escapes force `serde_json` onto the owned-string path,
63    // which `visit_str`-only visitors like `ustr::Ustr` reject as "expected a borrowed string".
64    let kwargs = PyDict::new(py);
65    kwargs.set_item("ensure_ascii", false)?;
66    let json_str: String = PyModule::import(py, "json")?
67        .call_method("dumps", (value,), Some(&kwargs))?
68        .extract()?;
69
70    let instance = serde_json::from_str(&json_str).map_err(to_pyvalue_err)?;
71    Ok(instance)
72}
73
74/// Convert a Rust type that implements `Serialize` to a Python dictionary.
75///
76/// # Errors
77///
78/// Returns an error if:
79/// - The Rust value cannot be serialized to JSON.
80/// - The JSON string cannot be parsed into a Python dictionary.
81/// - The Python `json` module fails to import or execute.
82pub fn to_dict_pyo3<T>(py: Python<'_>, value: &T) -> PyResult<Py<PyDict>>
83where
84    T: Serialize,
85{
86    let py_object = to_pyobject_pyo3(py, value)?;
87    let py_dict = py_object
88        .bind(py)
89        .cast::<PyDict>()
90        .map_err(Into::<PyErr>::into)?
91        .clone()
92        .unbind();
93    Ok(py_dict)
94}
95
96/// Convert a Rust type that implements `Serialize` to a Python object.
97///
98/// # Errors
99///
100/// Returns an error if:
101/// - The Rust value cannot be serialized to JSON.
102/// - The JSON string cannot be parsed into a Python object.
103/// - The Python `json` module fails to import or execute.
104pub fn to_pyobject_pyo3<T>(py: Python<'_>, value: &T) -> PyResult<Py<PyAny>>
105where
106    T: Serialize,
107{
108    let json_str = serde_json::to_string(value).map_err(to_pyvalue_err)?;
109    let py_object = PyModule::import(py, "json")?
110        .call_method("loads", (json_str,), None)?
111        .extract()?;
112    Ok(py_object)
113}
114
115/// Convert a Python mapping to an [`IndexMap`] using typed PyO3 objects when possible.
116///
117/// Falls back to the generic JSON bridge when the input is not a Python dict. Individual dict
118/// keys and values first try typed PyO3 extraction, then JSON/Serde extraction. This accepts both
119/// `{InstrumentId(...): Price(...)}` and `{"AUD/USD.SIM": "1.23456"}` style inputs.
120///
121/// # Errors
122///
123/// Returns an error if the Python object cannot be converted to the requested map type.
124pub fn indexmap_from_pyobject_pyo3<K, V>(
125    py: Python<'_>,
126    value: &Bound<'_, PyAny>,
127) -> PyResult<IndexMap<K, V>>
128where
129    K: for<'py> FromPyObjectOwned<'py> + DeserializeOwned + Eq + Hash,
130    V: for<'py> FromPyObjectOwned<'py> + DeserializeOwned,
131    IndexMap<K, V>: DeserializeOwned,
132{
133    let Ok(dict) = value.cast::<PyDict>() else {
134        return from_pyobject_pyo3(py, value);
135    };
136
137    let mut map = IndexMap::with_capacity(dict.len());
138    for (key, value) in dict.iter() {
139        map.insert(
140            extract_typed_or_json_pyo3(py, &key)?,
141            extract_typed_or_json_pyo3(py, &value)?,
142        );
143    }
144    Ok(map)
145}
146
147/// Convert a Python mapping to a [`HashMap`] using typed PyO3 objects when possible.
148///
149/// Falls back to the generic JSON bridge when the input is not a Python dict. Individual dict
150/// keys and values first try typed PyO3 extraction, then JSON/Serde extraction.
151///
152/// # Errors
153///
154/// Returns an error if the Python object cannot be converted to the requested map type.
155pub fn hashmap_from_pyobject_pyo3<K, V>(
156    py: Python<'_>,
157    value: &Bound<'_, PyAny>,
158) -> PyResult<HashMap<K, V>>
159where
160    K: for<'py> FromPyObjectOwned<'py> + DeserializeOwned + Eq + Hash,
161    V: for<'py> FromPyObjectOwned<'py> + DeserializeOwned,
162    HashMap<K, V>: DeserializeOwned,
163{
164    let Ok(dict) = value.cast::<PyDict>() else {
165        return from_pyobject_pyo3(py, value);
166    };
167
168    let mut map = HashMap::with_capacity(dict.len());
169    for (key, value) in dict.iter() {
170        map.insert(
171            extract_typed_or_json_pyo3(py, &key)?,
172            extract_typed_or_json_pyo3(py, &value)?,
173        );
174    }
175    Ok(map)
176}
177
178/// Convert an [`IndexMap`] to a Python dict using typed PyO3 keys and values.
179///
180/// # Errors
181///
182/// Returns an error if any key or value cannot be converted to Python.
183pub fn indexmap_to_pydict_pyo3<K, V>(py: Python<'_>, value: &IndexMap<K, V>) -> PyResult<Py<PyAny>>
184where
185    K: for<'py> IntoPyObject<'py> + Clone,
186    V: for<'py> IntoPyObject<'py> + Clone,
187{
188    let dict = PyDict::new(py);
189    for (key, value) in value {
190        dict.set_item(key.clone(), value.clone())?;
191    }
192    Ok(dict.into_any().unbind())
193}
194
195/// Convert a [`HashMap`] to a Python dict using typed PyO3 keys and values.
196///
197/// # Errors
198///
199/// Returns an error if any key or value cannot be converted to Python.
200pub fn hashmap_to_pydict_pyo3<K, V, S>(
201    py: Python<'_>,
202    value: &HashMap<K, V, S>,
203) -> PyResult<Py<PyAny>>
204where
205    K: for<'py> IntoPyObject<'py> + Clone,
206    V: for<'py> IntoPyObject<'py> + Clone,
207    S: BuildHasher,
208{
209    let dict = PyDict::new(py);
210    for (key, value) in value {
211        dict.set_item(key.clone(), value.clone())?;
212    }
213    Ok(dict.into_any().unbind())
214}
215
216fn extract_typed_or_json_pyo3<T>(py: Python<'_>, value: &Bound<'_, PyAny>) -> PyResult<T>
217where
218    T: for<'py> FromPyObjectOwned<'py> + DeserializeOwned,
219{
220    value.extract::<T>().or_else(|typed_err| {
221        let typed_err: PyErr = typed_err.into();
222        from_pyobject_pyo3(py, value).map_err(|json_err| {
223            to_pyvalue_err(format!(
224                "typed extraction failed: {typed_err}; JSON extraction failed: {json_err}"
225            ))
226        })
227    })
228}
229
230#[cfg(test)]
231mod tests {
232    use std::collections::HashMap;
233
234    use pyo3::types::PyDict;
235    use rstest::rstest;
236    use serde::{Deserialize, Serialize};
237
238    use super::*;
239
240    #[derive(Debug, PartialEq, Serialize, Deserialize)]
241    struct Payload {
242        values: HashMap<String, String>,
243    }
244
245    #[rstest]
246    fn test_from_pyobject_pyo3_preserves_non_ascii_strings() {
247        Python::initialize();
248        Python::attach(|py| {
249            let values = PyDict::new(py);
250            values.set_item("clé", "café").unwrap();
251
252            let dict = PyDict::new(py);
253            dict.set_item("values", values).unwrap();
254
255            let payload: Payload = from_pyobject_pyo3(py, dict.as_any()).unwrap();
256            assert_eq!(payload.values.get("clé").unwrap(), "café");
257        });
258    }
259}
nautilus_core/python/serialization.rs

nautilus_core/python/
serialization.rs
