feat(python): Add conversion helper functions to Python extension. (#231

)

New helper functions for converting from Pywr v1.x to v2.x JSON
strings added to the Python extension. Includes a new wrapper
around `Metric`.

pywr-python/Cargo.toml

@@ -22,7 +22,7 @@ pyo3-log = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 chrono = { workspace = true }
-
+pywr-v1-schema = { workspace = true }
 pywr-core = { path = "../pywr-core" }
 pywr-schema = { path = "../pywr-schema" }
 

pywr-python/pywr/__init__.py

@@ -1,7 +1,7 @@
 from pathlib import Path
 from typing import Optional
 
-from .pywr import Schema, Model  # type: ignore
+from .pywr import Schema, Model, convert_model_from_v1_json_string, convert_metric_from_v1_json_string  # type: ignore
 
 
 def run_from_path(

pywr-python/src/lib.rs

@@ -1,7 +1,7 @@
 use chrono::NaiveDateTime;
 use pyo3::exceptions::PyRuntimeError;
 use pyo3::prelude::*;
-use pyo3::types::{PyDict, PyType};
+use pyo3::types::{PyDict, PyTuple, PyType};
 
 /// Python API
 ///
@@ -16,6 +16,8 @@ use pywr_core::solvers::{ClpSolver, ClpSolverSettings, ClpSolverSettingsBuilder}
 #[cfg(feature = "highs")]
 use pywr_core::solvers::{HighsSolver, HighsSolverSettings, HighsSolverSettingsBuilder};
 use pywr_schema::model::DateType;
+use pywr_schema::parameters::TryIntoV2Parameter;
+use pywr_schema::ConversionError;
 use std::fmt;
 use std::path::PathBuf;
 use std::str::FromStr;
@@ -95,13 +97,56 @@ impl Schema {
         Ok(data)
     }
 
-    /// Convert the schema to a Pywr model.
+    /// Build the schema in to a Pywr model.
     fn build(&mut self, data_path: Option<PathBuf>, output_path: Option<PathBuf>) -> PyResult<Model> {
         let model = self.schema.build_model(data_path.as_deref(), output_path.as_deref())?;
         Ok(Model { model })
     }
 }
 
+/// Convert a Pywr v1.x JSON string to a Pywr v2.x schema.
+#[pyfunction]
+fn convert_model_from_v1_json_string(py: Python, data: &str) -> PyResult<Py<PyTuple>> {
+    // Try to convert
+    let (schema, errors) =
+        pywr_schema::PywrModel::from_v1_str(data).map_err(|e| PyRuntimeError::new_err(e.to_string()))?;
+
+    // Create a new schema object
+    let py_schema = Schema { schema };
+    let py_errors = errors.into_iter().map(|e| e.to_string()).collect::<Vec<_>>();
+
+    let result = PyTuple::new_bound(py, &[py_schema.into_py(py), py_errors.into_py(py)]).into();
+    Ok(result)
+}
+
+#[pyclass]
+pub struct Metric {
+    metric: pywr_schema::metric::Metric,
+}
+
+#[pymethods]
+impl Metric {
+    /// Serialize the metric to a JSON string.
+    fn to_json_string(&self) -> PyResult<String> {
+        let data = serde_json::to_string_pretty(&self.metric).map_err(|e| PyRuntimeError::new_err(e.to_string()))?;
+        Ok(data)
+    }
+}
+
+/// Convert a Pywr v1.x JSON string to a Pywr v2.x metric.
+#[pyfunction]
+fn convert_metric_from_v1_json_string(_py: Python, data: &str) -> PyResult<Metric> {
+    let v1: pywr_v1_schema::parameters::ParameterValue =
+        serde_json::from_str(data).map_err(|e| PyRuntimeError::new_err(e.to_string()))?;
+
+    let metric = v1
+        .try_into_v2_parameter(None, &mut 0)
+        .map_err(|e: ConversionError| PyRuntimeError::new_err(e.to_string()))?;
+
+    let py_metric = Metric { metric };
+    Ok(py_metric)
+}
+
 #[pyclass]
 pub struct Model {
     model: pywr_core::models::Model,
@@ -203,8 +248,11 @@ fn build_highs_settings(kwargs: Option<&Bound<'_, PyDict>>) -> PyResult<HighsSol
 fn pywr(_py: Python, m: &Bound<'_, PyModule>) -> PyResult<()> {
     pyo3_log::init();
 
+    m.add_function(wrap_pyfunction!(convert_model_from_v1_json_string, m)?)?;
+    m.add_function(wrap_pyfunction!(convert_metric_from_v1_json_string, m)?)?;
     m.add_class::<Schema>()?;
     m.add_class::<Model>()?;
+    m.add_class::<Metric>()?;
 
     Ok(())
 }

pywr-schema/src/model.rs

@@ -667,6 +667,15 @@ impl PywrModel {
             errors,
         )
     }
+
+    /// Convert a v1 JSON string to a v2 model.
+    ///
+    /// See [`PywrModel::from_v1`] for more information.
+    pub fn from_v1_str(v1: &str) -> Result<(Self, Vec<ConversionError>), pywr_v1_schema::model::PywrSchemaError> {
+        let v1_model: pywr_v1_schema::PywrModel = serde_json::from_str(v1)?;
+
+        Ok(Self::from_v1(v1_model))
+    }
 }
 
 #[derive(serde::Deserialize, serde::Serialize, Clone)]