from pathlib import Path
import importlib
-T = TypeVar('T') # pylint: disable=invalid-name
+from .server.content_types import CONTENT_JSON
+
+T = TypeVar('T')
FormatFunc = Callable[[T, Mapping[str, Any]], str]
+ErrorFormatFunc = Callable[[str, str, int], str]
class FormatDispatcher:
- """ Helper class to conveniently create formatting functions in
- a module using decorators.
+ """ Container for formatting functions for results.
+ Functions can conveniently be added by using decorated functions.
"""
- def __init__(self) -> None:
+ def __init__(self, content_types: Optional[Mapping[str, str]] = None) -> None:
+ self.error_handler: ErrorFormatFunc = lambda ct, msg, status: f"ERROR {status}: {msg}"
+ self.content_types: Dict[str, str] = {}
+ if content_types:
+ self.content_types.update(content_types)
self.format_functions: Dict[Type[Any], Dict[str, FormatFunc[Any]]] = defaultdict(dict)
-
def format_func(self, result_class: Type[T],
fmt: str) -> Callable[[FormatFunc[T]], FormatFunc[T]]:
""" Decorator for a function that formats a given type of result into the
return decorator
+ def error_format_func(self, func: ErrorFormatFunc) -> ErrorFormatFunc:
+ """ Decorator for a function that formats error messges.
+ There is only one error formatter per dispatcher. Using
+ the decorator repeatedly will overwrite previous functions.
+ """
+ self.error_handler = func
+ return func
def list_formats(self, result_type: Type[Any]) -> List[str]:
""" Return a list of formats supported by this formatter.
"""
return list(self.format_functions[result_type].keys())
-
def supports_format(self, result_type: Type[Any], fmt: str) -> bool:
""" Check if the given format is supported by this formatter.
"""
return fmt in self.format_functions[result_type]
-
def format_result(self, result: Any, fmt: str, options: Mapping[str, Any]) -> str:
""" Convert the given result into a string using the given format.
"""
return self.format_functions[type(result)][fmt](result, options)
+ def format_error(self, content_type: str, msg: str, status: int) -> str:
+ """ Convert the given error message into a response string
+ taking the requested content_type into account.
+
+ Change the format using the error_format_func decorator.
+ """
+ return self.error_handler(content_type, msg, status)
+
+ def set_content_type(self, fmt: str, content_type: str) -> None:
+ """ Set the content type for the given format. This is the string
+ that will be returned in the Content-Type header of the HTML
+ response, when the given format is choosen.
+ """
+ self.content_types[fmt] = content_type
+
+ def get_content_type(self, fmt: str) -> str:
+ """ Return the content type for the given format.
+
+ If no explicit content type has been defined, then
+ JSON format is assumed.
+ """
+ return self.content_types.get(fmt, CONTENT_JSON)
+
def load_format_dispatcher(api_name: str, project_dir: Optional[Path]) -> FormatDispatcher:
""" Load the dispatcher for the given API.