feat: Update cast exception to include original value

Prior, the cast exception would contain the cast-value and not the original value, which can be confusing when reporting the validation error to users.

Author: courtney-miles

src/Fields/BaseField.php

@@ -151,17 +151,25 @@ final public function castValue($val)
             }
 
             return null;
-        } else {
-            $val = $this->validateCastValue($val);
-            if (!$this->constraintsDisabled) {
-                $validationErrors = $this->checkConstraints($val);
-                if (count($validationErrors) > 0) {
-                    throw new FieldValidationException($validationErrors);
+        }
+
+        $castVal = $this->validateCastValue($val);
+
+        if (!$this->constraintsDisabled) {
+            $validationErrors = $this->checkConstraints($castVal);
+
+            if (count($validationErrors) > 0) {
+                foreach ($validationErrors as $i => $schemaError) {
+                    \assert($schemaError instanceof SchemaValidationError);
+                    $schemaError->extraDetails['value'] = $val;
+                    $validationErrors[$i] = $schemaError;
                 }
-            }
 
-            return $val;
+                throw new FieldValidationException($validationErrors);
+            }
         }
+
+        return $castVal;
     }
 
     public function validateValue($val)
@@ -171,12 +179,6 @@ public function validateValue($val)
 
             return [];
         } catch (FieldValidationException $e) {
-            foreach ($e->validationErrors as $ve) {
-                // Replace the cast-value for the violation, with the original value.
-                // This so the error message contains the original representation of the invalid value.
-                $ve->extraDetails['value'] = $val;
-            }
-
             return $e->validationErrors;
         }
     }

tests/Fields/BaseFieldTest.php

@@ -4,6 +4,7 @@
 
 namespace Fields;
 
+use frictionlessdata\tableschema\Exceptions\FieldValidationException;
 use frictionlessdata\tableschema\Fields\BaseField;
 use PHPUnit\Framework\TestCase;
 
@@ -12,7 +13,7 @@
  */
 class BaseFieldTest extends TestCase
 {
-    public function testPreserveOriginalValueInValidationError(): void
+    public function testPreserveOriginalValueInValidateError(): void
     {
         $descriptor = (object) [
             'name' => 'date_col',
@@ -38,4 +39,44 @@ protected function validateCastValue($val)
             $error->extraDetails['value']
         );
     }
+
+    public function testPreserveOriginalValueInCastError(): void
+    {
+        $descriptor = (object) [
+            'name' => 'date_col',
+            'constraints' => (object) ['minimum' => '2025-07-01'],
+        ];
+
+        $sut = new class($descriptor) extends BaseField {
+            protected function validateCastValue($val)
+            {
+                // If the logic is wrong, this object will be in the error
+                // instead of the original date string.
+                return new \DateTimeImmutable($val);
+            }
+        };
+
+        $validatedValue = '2025-06-30';
+        $exception = null;
+
+        try {
+            $sut->castValue($validatedValue);
+        } catch (FieldValidationException $exception) {
+        }
+
+        self::assertNotNull($exception, 'An exception is expected for this test.');
+        self::assertSame(
+            'date_col: value is below minimum ("2025-06-30")',
+            $exception->getMessage()
+        );
+
+        $errors = $exception->validationErrors;
+
+        self::assertCount(1, $errors);
+        $error = reset($errors);
+        self::assertSame(
+            $validatedValue,
+            $error->extraDetails['value']
+        );
+    }
 }