Introduce exactness into Decimal validation logic (#1405)

Author: sydney-runkle

src/input/input_abstract.rs

@@ -98,18 +98,7 @@ pub trait Input<'py>: fmt::Debug + ToPyObject {
 
     fn validate_float(&self, strict: bool) -> ValMatch<EitherFloat<'_>>;
 
-    fn validate_decimal(&self, strict: bool, py: Python<'py>) -> ValResult<Bound<'py, PyAny>> {
-        if strict {
-            self.strict_decimal(py)
-        } else {
-            self.lax_decimal(py)
-        }
-    }
-    fn strict_decimal(&self, py: Python<'py>) -> ValResult<Bound<'py, PyAny>>;
-    #[cfg_attr(has_coverage_attribute, coverage(off))]
-    fn lax_decimal(&self, py: Python<'py>) -> ValResult<Bound<'py, PyAny>> {
-        self.strict_decimal(py)
-    }
+    fn validate_decimal(&self, strict: bool, py: Python<'py>) -> ValMatch<Bound<'py, PyAny>>;
 
     type Dict<'a>: ValidatedDict<'py>
     where

src/input/input_json.rs

@@ -167,12 +167,13 @@ impl<'py, 'data> Input<'py> for JsonValue<'data> {
         }
     }
 
-    fn strict_decimal(&self, py: Python<'py>) -> ValResult<Bound<'py, PyAny>> {
+    fn validate_decimal(&self, _strict: bool, py: Python<'py>) -> ValMatch<Bound<'py, PyAny>> {
         match self {
-            JsonValue::Float(f) => create_decimal(&PyString::new_bound(py, &f.to_string()), self),
-
+            JsonValue::Float(f) => {
+                create_decimal(&PyString::new_bound(py, &f.to_string()), self).map(ValidationMatch::strict)
+            }
             JsonValue::Str(..) | JsonValue::Int(..) | JsonValue::BigInt(..) => {
-                create_decimal(self.to_object(py).bind(py), self)
+                create_decimal(self.to_object(py).bind(py), self).map(ValidationMatch::strict)
             }
             _ => Err(ValError::new(ErrorTypeDefaults::DecimalType, self)),
         }
@@ -399,8 +400,8 @@ impl<'py> Input<'py> for str {
         str_as_float(self, self).map(ValidationMatch::lax)
     }
 
-    fn strict_decimal(&self, py: Python<'py>) -> ValResult<Bound<'py, PyAny>> {
-        create_decimal(self.to_object(py).bind(py), self)
+    fn validate_decimal(&self, _strict: bool, py: Python<'py>) -> ValMatch<Bound<'py, PyAny>> {
+        create_decimal(self.to_object(py).bind(py), self).map(ValidationMatch::lax)
     }
 
     type Dict<'a> = Never;

src/input/input_python.rs

@@ -251,8 +251,8 @@ impl<'py> Input<'py> for Bound<'py, PyAny> {
                     str_as_int(self, s)
                 } else if self.is_exact_instance_of::<PyFloat>() {
                     float_as_int(self, self.extract::<f64>()?)
-                } else if let Ok(decimal) = self.strict_decimal(self.py()) {
-                    decimal_as_int(self, &decimal)
+                } else if let Ok(decimal) = self.validate_decimal(true, self.py()) {
+                    decimal_as_int(self, &decimal.into_inner())
                 } else if let Ok(float) = self.extract::<f64>() {
                     float_as_int(self, float)
                 } else if let Some(enum_val) = maybe_as_enum(self) {
@@ -310,48 +310,44 @@ impl<'py> Input<'py> for Bound<'py, PyAny> {
         Err(ValError::new(ErrorTypeDefaults::FloatType, self))
     }
 
-    fn strict_decimal(&self, py: Python<'py>) -> ValResult<Bound<'py, PyAny>> {
+    fn validate_decimal(&self, strict: bool, py: Python<'py>) -> ValMatch<Bound<'py, PyAny>> {
         let decimal_type = get_decimal_type(py);
+
         // Fast path for existing decimal objects
         if self.is_exact_instance(decimal_type) {
-            return Ok(self.to_owned());
+            return Ok(ValidationMatch::exact(self.to_owned().clone()));
+        }
+
+        if !strict {
+            if self.is_instance_of::<PyString>() || (self.is_instance_of::<PyInt>() && !self.is_instance_of::<PyBool>())
+            {
+                // Checking isinstance for str / int / bool is fast compared to decimal / float
+                return create_decimal(self, self).map(ValidationMatch::lax);
+            }
+
+            if self.is_instance_of::<PyFloat>() {
+                return create_decimal(self.str()?.as_any(), self).map(ValidationMatch::lax);
+            }
         }
 
-        // Try subclasses of decimals, they will be upcast to Decimal
         if self.is_instance(decimal_type)? {
-            return create_decimal(self, self);
+            // Upcast subclasses to decimal
+            return create_decimal(self, self).map(ValidationMatch::strict);
         }
 
-        Err(ValError::new(
+        let error_type = if strict {
             ErrorType::IsInstanceOf {
                 class: decimal_type
                     .qualname()
                     .and_then(|name| name.extract())
                     .unwrap_or_else(|_| "Decimal".to_owned()),
                 context: None,
-            },
-            self,
-        ))
-    }
-
-    fn lax_decimal(&self, py: Python<'py>) -> ValResult<Bound<'py, PyAny>> {
-        let decimal_type = get_decimal_type(py);
-        // Fast path for existing decimal objects
-        if self.is_exact_instance(decimal_type) {
-            return Ok(self.to_owned().clone());
-        }
-
-        if self.is_instance_of::<PyString>() || (self.is_instance_of::<PyInt>() && !self.is_instance_of::<PyBool>()) {
-            // checking isinstance for str / int / bool is fast compared to decimal / float
-            create_decimal(self, self)
-        } else if self.is_instance(decimal_type)? {
-            // upcast subclasses to decimal
-            return create_decimal(self, self);
-        } else if self.is_instance_of::<PyFloat>() {
-            create_decimal(self.str()?.as_any(), self)
+            }
         } else {
-            Err(ValError::new(ErrorTypeDefaults::DecimalType, self))
-        }
+            ErrorTypeDefaults::DecimalType
+        };
+
+        Err(ValError::new(error_type, self))
     }
 
     type Dict<'a> = GenericPyMapping<'a, 'py> where Self: 'a;

src/input/input_string.rs

@@ -143,9 +143,9 @@ impl<'py> Input<'py> for StringMapping<'py> {
         }
     }
 
-    fn strict_decimal(&self, _py: Python<'py>) -> ValResult<Bound<'py, PyAny>> {
+    fn validate_decimal(&self, _strict: bool, _py: Python<'py>) -> ValMatch<Bound<'py, PyAny>> {
         match self {
-            Self::String(s) => create_decimal(s, self),
+            Self::String(s) => create_decimal(s, self).map(ValidationMatch::strict),
             Self::Mapping(_) => Err(ValError::new(ErrorTypeDefaults::DecimalType, self)),
         }
     }

src/validators/decimal.rs

@@ -122,7 +122,7 @@ impl Validator for DecimalValidator {
         input: &(impl Input<'py> + ?Sized),
         state: &mut ValidationState<'_, 'py>,
     ) -> ValResult<PyObject> {
-        let decimal = input.validate_decimal(state.strict_or(self.strict), py)?;
+        let decimal = input.validate_decimal(state.strict_or(self.strict), py)?.unpack(state);
 
         if !self.allow_inf_nan || self.check_digits {
             if !decimal.call_method0(intern!(py, "is_finite"))?.extract()? {

tests/validators/test_decimal.py

@@ -9,7 +9,7 @@
 import pytest
 from dirty_equals import FunctionCheck, IsStr
 
-from pydantic_core import SchemaValidator, ValidationError
+from pydantic_core import SchemaValidator, ValidationError, core_schema
 
 from ..conftest import Err, PyAndJson, plain_repr
 
@@ -467,3 +467,23 @@ def test_validate_max_digits_and_decimal_places_edge_case() -> None:
     assert v.validate_python(Decimal('9999999999999999.999999999999999999')) == Decimal(
         '9999999999999999.999999999999999999'
     )
+
+
+def test_str_validation_w_strict() -> None:
+    s = SchemaValidator(core_schema.decimal_schema(strict=True))
+
+    with pytest.raises(ValidationError):
+        assert s.validate_python('1.23')
+
+
+def test_str_validation_w_lax() -> None:
+    s = SchemaValidator(core_schema.decimal_schema(strict=False))
+
+    assert s.validate_python('1.23') == Decimal('1.23')
+
+
+def test_union_with_str_prefers_str() -> None:
+    s = SchemaValidator(core_schema.union_schema([core_schema.decimal_schema(), core_schema.str_schema()]))
+
+    assert s.validate_python('1.23') == '1.23'
+    assert s.validate_python(1.23) == Decimal('1.23')