mia-accounting-django/mia_core/stored_post.py

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# The core application of the Mia project.
# by imacat <imacat@mail.imacat.idv.tw>, 2020/7/24
# Copyright (c) 2020 imacat.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""The session-based POST data storage management of the Mia core application.
"""
import random
from django.http import HttpResponseRedirect
from .utils import UrlBuilder
STORAGE_KEY = "stored_post"
def error_redirect(request, url, post):
"""Redirects to a specific URL on error, with the POST data ID appended
as the query parameter "s". The POST data can be loaded with the
get_previous_post() utility.
Args:
request (HttpRequest): The request.
url (str): The destination URL.
post (dict[str]): The POST data.
Returns:
HttpResponseRedirect: The redirect response.
"""
post_id = _store(request, post)
return HttpResponseRedirect(str(UrlBuilder(url).query(s=post_id)))
def get_previous_post(request):
"""Retrieves the previously-stored POST data.
Args:
request (HttpRequest): The request.
Returns:
dict: The previously-stored POST data.
"""
if "s" not in request.GET:
return None
return _retrieve(request, request.GET["s"])
def _store(request, post):
"""Stores the POST data into the session, and returns the POST data ID that
can be used to retrieve it later with _retrieve().
Args:
request (HttpRequest): The request.
post (dict): The POST data.
Returns:
str: The POST data ID
"""
if STORAGE_KEY not in request.session:
request.session[STORAGE_KEY] = {}
post_id = _new_post_id(request.session[STORAGE_KEY])
request.session[STORAGE_KEY][post_id] = post
return post_id
def _retrieve(request, post_id):
"""Retrieves the POST data from the storage.
Args:
request (HttpRequest): The request.
post_id (str): The POST data ID.
Returns:
dict: The POST data, or None if the corresponding data does not exist.
"""
if STORAGE_KEY not in request.session:
return None
if post_id not in request.session[STORAGE_KEY]:
return None
return request.session[STORAGE_KEY][post_id]
def _new_post_id(post_store):
"""Generates and returns a new POST ID that does not exist yet.
Args:
post_store (dict): The POST storage.
Returns:
str: The newly-generated POST ID.
"""
while True:
post_id = ""
while len(post_id) < 16:
n = random.randint(1, 64)
if n < 26:
post_id = post_id + chr(ord("a") + n)
elif n < 52:
post_id = post_id + chr(ord("a") + (n - 26))
elif n < 62:
post_id = post_id + chr(ord("0") + (n - 52))
else:
post_id = post_id + "-_."[n - 62]
if post_id not in post_store:
return post_id