implement __reduce__ to make SchemaValidator picklable (pydantic#53)

* attempt at implementing __reduce__

* python version

* remove loc

* back to rust

* use array

* minimize changes

* again use array

* remove import

* test all protocol versions

* Update src/validators/mod.rs

Co-authored-by: Samuel Colvin <[email protected]>

* Update src/validators/mod.rs

Co-authored-by: Samuel Colvin <[email protected]>

* pr feedback

* pointlessly tweak layout

Co-authored-by: Samuel Colvin <[email protected]>
Co-authored-by: Samuel Colvin <[email protected]>

Author: adriangb

src/validators/mod.rs

@@ -28,11 +28,12 @@ mod set;
 mod string;
 mod union;
 
-#[pyclass]
+#[pyclass(module = "pydantic_core._pydantic_core")]
 #[derive(Debug, Clone)]
 pub struct SchemaValidator {
     validator: CombinedValidator,
     slots: Vec<CombinedValidator>,
+    schema: PyObject,
 }
 
 #[pymethods]
@@ -50,7 +51,17 @@ impl SchemaValidator {
             }
         };
         let slots = slots_builder.into_slots()?;
-        Ok(Self { validator, slots })
+        Ok(Self {
+            validator,
+            slots,
+            schema: schema.into_py(py),
+        })
+    }
+
+    fn __reduce__(&self, py: Python) -> PyResult<PyObject> {
+        let args = (self.schema.as_ref(py),);
+        let cls = Py::new(py, self.to_owned())?.getattr(py, "__class__")?;
+        Ok((cls, args).into_py(py))
     }
 
     fn validate_python(&self, py: Python, input: &PyAny) -> PyResult<PyObject> {

tests/test_build.py

@@ -1,3 +1,5 @@
+import pickle
+
 import pytest
 
 from pydantic_core import SchemaError, SchemaValidator
@@ -39,3 +41,13 @@ def test_schema_wrong_type():
     assert exc_info.value.args[0] == (
         "Schema build error:\n  TypeError: 'int' object cannot be converted to 'PyString'"
     )
+
+
+@pytest.mark.parametrize('pickle_protocol', range(1, pickle.HIGHEST_PROTOCOL + 1))
+def test_pickle(pickle_protocol: int) -> None:
+    v1 = SchemaValidator({'type': 'bool'})
+    assert v1.validate_python('tRuE') is True
+    p = pickle.dumps(v1, protocol=pickle_protocol)
+    v2 = pickle.loads(p)
+    assert v2.validate_python('tRuE') is True
+    assert repr(v1) == repr(v2)