Fix JSON type + update Enum (#72)

* The JSON type can also be a list, and is not restricted to a dict.
* Added the `enums` attribute to `Enum` class

Author: mehdigmira

sqlalchemy-stubs/sql/sqltypes.pyi

@@ -172,6 +172,7 @@ class Enum(Emulated, String, SchemaType):
     native_enum: bool = ...
     create_constraint: bool = ...
     validate_strings: bool = ...
+    enums: List[typing_Text] = ...  # This is set inside _setup_for_values.
     def __init__(self, *enums: Any, **kw: Any) -> None: ...
     @property
     def native(self) -> bool: ...
@@ -243,7 +244,9 @@ class Interval(Emulated, _AbstractInterval[timedelta], TypeDecorator[timedelta])
     def bind_processor(self, dialect: Dialect) -> Callable[[Optional[timedelta]], str]: ...
     def result_processor(self, dialect: Dialect, coltype: Any) -> Callable[[Optional[str]], Optional[timedelta]]: ...
 
-class JSON(Indexable, TypeEngine[Dict[str, Any]]):
+_JSONT = Union[Dict[str, Any], List[Any]]
+
+class JSON(Indexable, TypeEngine[_JSONT]):
     __visit_name__: str = ...
     hashable: bool = ...
     NULL: util.symbol = ...
@@ -257,12 +260,13 @@ class JSON(Indexable, TypeEngine[Dict[str, Any]]):
     class JSONIndexType(JSONElementType): ...
     class JSONPathType(JSONElementType): ...
     comparator_factory: Type[Any] = ...
+    # This method returns `dict`, but it seems to be a bug in SQLAlchemy.
     @property
     def python_type(self) -> Type[Dict[str, Any]]: ...
     @property
     def should_evaluate_none(self) -> bool: ...  # type: ignore  # incompatible with supertype "TypeEngine"
-    def bind_processor(self, dialect: Dialect) -> Callable[[Optional[Dict[str, Any]]], Optional[str]]: ...
-    def result_processor(self, dialect: Dialect, coltype: Any) -> Callable[[Optional[str]], Optional[Dict[str, Any]]]: ...
+    def bind_processor(self, dialect: Dialect) -> Callable[[Optional[_JSONT]], Optional[str]]: ...
+    def result_processor(self, dialect: Dialect, coltype: Any) -> Callable[[Optional[str]], Optional[_JSONT]]: ...
 
 class ARRAY(Indexable, Concatenable, TypeEngine[List[_T]]):
     __visit_name__: str = ...