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- from typing import Any, Callable, Dict, List
- def before_request(
- hook: Callable[[], Any] = None, only: List[str] = None
- ) -> Callable[..., Any]:
- """
- This decorator provides a way to hook into the request
- lifecycle by enqueueing methods to be invoked before
- each handler in the view. If the method returns a value
- other than :code:`None`, then that value will be returned
- to the client. If invoked with the :code:`only` kwarg,
- the hook will only be invoked for the given list of
- handler methods.
- Examples::
- class MyFeature(ModelView)
- @before_request
- def ensure_feature_is_enabled(self):
- if self.feature_is_disabled:
- return self.response_404()
- return None
- # etc...
- class MyView(ModelRestAPI):
- @before_request(only=["create", "update", "delete"])
- def ensure_write_mode_enabled(self):
- if self.read_only:
- return self.response_400()
- return None
- # etc...
- :param hook:
- A callable to be invoked before handlers in the class. If the
- hook returns :code:`None`, then the request proceeds and the
- handler is invoked. If it returns something other than :code:`None`,
- then execution halts and that value is returned to the client.
- :param only:
- An optional list of the names of handler methods. If present,
- :code:`hook` will only be invoked before the handlers specified
- in the list. If absent, :code:`hook` will be invoked for before
- all handlers in the class.
- """
- def wrap(hook: Callable[[], Any]) -> Callable[[], Any]:
- hook._before_request_hook = True
- hook._before_request_only = only
- return hook
- return wrap if hook is None else wrap(hook)
- def wrap_route_handler_with_hooks(
- handler_name: str,
- handler: Callable[..., Any],
- before_request_hooks: List[Callable[[], Any]],
- ) -> Callable[..., Any]:
- applicable_hooks = []
- for hook in before_request_hooks:
- only = hook._before_request_only
- applicable_hook = only is None or handler_name in only
- if applicable_hook:
- applicable_hooks.append(hook)
- if not applicable_hooks:
- return handler
- def wrapped_handler(*args: List[Any], **kwargs: Dict[str, Any]) -> Any:
- for hook in applicable_hooks:
- result = hook()
- if result is not None:
- return result
- return handler(*args, **kwargs)
- return wrapped_handler
- def get_before_request_hooks(view_or_api_instance: Any) -> List[Callable[[], Any]]:
- before_request_hooks = []
- for attr_name in dir(view_or_api_instance):
- attr = getattr(view_or_api_instance, attr_name)
- if hasattr(attr, "_before_request_hook") and attr._before_request_hook is True:
- before_request_hooks.append(attr)
- return before_request_hooks
|
