Update error message for enum validator (#673)

* Update error message for enum validator

* Update history

HISTORY.rst

@@ -8,6 +8,7 @@ v0.31 (unreleased)
 * better support for floating point `multiple_of` values, #652 by @justindujardin
 * fix schema generation for ``NewType`` and ``Literal``, #649 by @dmontagu
 * fix ``alias_generator`` and field config conflict, #645 by @gmetzker and #658 by @MrMrRobat
+* more detailed message for ``EnumError``, #673 by @dmontagu
 * add advanced exclude support for ``dict``, ``json`` and ``copy``, #648 by @MrMrRobat
 * fix bug in ``GenericModel`` for models with concrete parameterized fields, #672 by @dmontagu
 * add documentation for Literal type, #651 by @dmontagu

pydantic/errors.py

@@ -86,7 +86,9 @@ class UrlRegexError(PydanticValueError):
 
 
 class EnumError(PydanticTypeError):
-    msg_template = 'value is not a valid enumeration member'
+    def __str__(self) -> str:
+        permitted = ', '.join(repr(v.value) for v in self.ctx['enum_type'])  # type: ignore
+        return f'value is not a valid enumeration member; permitted: {permitted}'
 
 
 class IntegerError(PydanticTypeError):

pydantic/validators.py

@@ -219,9 +219,10 @@ def set_validator(v: Any) -> Set[Any]:
 
 
 def enum_validator(v: Any, field: 'Field', config: 'BaseConfig') -> Enum:
-    with change_exception(errors.EnumError, ValueError):
+    try:
         enum_v = field.type_(v)
-
+    except ValueError:
+        raise errors.EnumError(enum_type=field.type_)
     return enum_v.value if config.use_enum_values else enum_v
 
 

tests/test_types.py

@@ -473,7 +473,12 @@ def test_enum_fails():
     with pytest.raises(ValueError) as exc_info:
         CookingModel(tool=3)
     assert exc_info.value.errors() == [
-        {'loc': ('tool',), 'msg': 'value is not a valid enumeration member', 'type': 'type_error.enum'}
+        {
+            'loc': ('tool',),
+            'msg': 'value is not a valid enumeration member; permitted: 1, 2',
+            'type': 'type_error.enum',
+            'ctx': {'enum_type': ToolEnum},
+        }
     ]