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"""Wrap requests functions with monads."""
import traceback
from typing import Union, Optional, Callable
import requests
from requests.models import Response
from pymonad.either import Left, Right, Either
from flask import (
flash,
request,
redirect,
render_template,
current_app as app,
escape as flask_escape)
# HTML Status codes indicating a successful request.
SUCCESS_CODES = (200, 201, 202, 203, 204, 205, 206, 207, 208, 226)
# Possible error(s) that can be encontered while attempting to do a request.
PossibleError = Union[Response, Exception]
def make_error_handler(
redirect_to: Optional[Response] = None,
cleanup_thunk: Callable = lambda *args: None
) -> Callable[[PossibleError], Response]:
"""
Build a function to gracefully handle errors encountered while doing
requests.
:rtype: Callable
"""
redirect_to = redirect_to or redirect(request.url)
def __handler__(resp_or_exc: PossibleError) -> Response:
cleanup_thunk()
if issubclass(type(resp_or_exc), Exception):
# Is an exception!
return render_template(
"unhandled_exception.html",
trace=traceback.format_exception(resp_or_exc))
if isinstance(resp_or_exc, Response):
flash("The authorisation server responded with "
f"({flask_escape(resp_or_exc.status_code)}, "
f"{flask_escape(resp_or_exc.reason)}) for the request to "
f"'{flask_escape(resp_or_exc.request.url)}'",
"alert-danger")
return redirect_to
flash("Unspecified error!", "alert-danger")
app.logger.debug("Error (%s): %s", type(resp_or_exc), resp_or_exc)
return redirect_to
return __handler__
def get(url, params=None, **kwargs) -> Either:
"""
A wrapper around `requests.get` function.
Takes the same arguments as `requests.get`.
:rtype: pymonad.either.Either
"""
try:
resp = requests.get(url, params=params, **kwargs)
if resp.status_code in SUCCESS_CODES:
return Right(resp.json())
return Left(resp)
except requests.exceptions.RequestException as exc:
return Left(exc)
def post(url, data=None, json=None, **kwargs) -> Either:
"""
A wrapper around `requests.post` function.
Takes the same arguments as `requests.post`.
:rtype: pymonad.either.Either
"""
try:
resp = requests.post(url, data=data, json=json, **kwargs)
if resp.status_code in SUCCESS_CODES:
return Right(resp.json())
return Left(resp)
except requests.exceptions.RequestException as exc:
return Left(exc)
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