mia-accounting-django/mia_core/utils.py

494 lines
15 KiB
Python

# The core application of the Mia project.
# by imacat <imacat@mail.imacat.idv.tw>, 2020/7/1
# 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 utilities of the Mia core application.
"""
import random
import urllib.parse
from django.conf import settings
from django.db.models import Model, Q
from django.utils.translation import pgettext, get_language
def new_pk(cls):
"""Finds a random ID that does not conflict with the existing data records.
Args:
cls (class): The Django model class.
Returns:
int: The new random ID.
"""
while True:
pk = random.randint(100000000, 999999999)
try:
cls.objects.get(pk=pk)
except cls.DoesNotExist:
return pk
def strip_form(form):
"""Strips the values of a form. Empty strings are converted to None.
Args:
form (dict[str]): The form.
"""
for key in list(form.keys()):
form[key] = form[key].strip()
if form[key] == "":
del form[key]
class Language:
"""A language.
Args:
language (str): The Django language code.
Attributes:
id (str): The language ID
db (str): The database column suffix of this language.
locale (str); The locale name of this language.
is_default (bool): Whether this is the default language.
"""
def __init__(self, language):
self.id = language
self.db = "_" + language.lower().replace("-", "_")
if language == "zh-hant":
self.locale = "zh-TW"
elif language == "zh-hans":
self.locale = "zh-CN"
else:
self.locale = language
self.is_default = (language == settings.LANGUAGE_CODE)
@staticmethod
def default():
return Language(settings.LANGUAGE_CODE)
@staticmethod
def current():
return Language(get_language())
def get_multi_lingual_attr(model, name, default=None):
"""Returns a multi-lingual attribute of a data model.
Args:
model (object): The data model.
name (str): The attribute name.
default (str): The default language.
Returns:
(any): The attribute in this language, or in the default
language if there is no content in the current language.
"""
language = Language.current()
title = getattr(model, name + language.db)
if default is None:
default = Language.default().id
if language.id == default:
return title
if title is not None:
return title
return getattr(model, name + Language.default().db)
def set_multi_lingual_attr(model, name, value):
"""Sets a multi-lingual attribute of a data model.
Args:
model (object): The data model.
name (str): The attribute name.
value (any): The new value
"""
language = Language.current()
setattr(model, name + language.db, value)
def get_multi_lingual_search(attr, query):
"""Returns the query condition on a multi-lingual attribute.
Args:
attr (str): The base name of the multi-lingual attribute.
query (str): The query.
Returns:
Q: The query condition
"""
language = Language.current()
if language.is_default:
return Q(**{attr + language.db + "__icontains": query})
default = Language.default()
q = (Q(**{attr + language.db + "__isnull": False})
& Q(**{attr + language.db + "__icontains": query}))\
| (Q(**{attr + language.db + "__isnull": True})
& Q(**{attr + default.db + "__icontains": query}))
return q
class UrlBuilder:
"""The URL builder.
Attributes:
base_path (str): the base path
params (list[Param]): The query parameters
"""
def __init__(self, start_url):
"""Constructs a new URL builder.
Args:
start_url (str): The URL to start with
"""
pos = start_url.find("?")
if pos == -1:
self.base_path = start_url
self.params = []
return
self.base_path = start_url[:pos]
self.params = []
for piece in start_url[pos + 1:].split("&"):
pos = piece.find("=")
name = urllib.parse.unquote(piece[:pos])
value = urllib.parse.unquote(piece[pos + 1:])
self.params.append(self.Param(name, value))
def add(self, name, value):
"""Adds a query parameter.
Args:
name (str): The parameter name
value (str): The parameter value
Returns:
UrlBuilder: The URL builder itself, with the parameter
modified.
"""
if value is not None:
self.params.append(self.Param(name, value))
return self
def remove(self, name):
"""Removes a query parameter.
Args:
name (str): The parameter name
Returns:
UrlBuilder: The URL builder itself, with the parameter
modified.
"""
self.params = [x for x in self.params if x.name != name]
return self
def query(self, **kwargs):
"""A keyword-styled query parameter setter. The existing values are
always replaced. Multiple-values are added when the value is a list or
tuple. The existing values are dropped when the value is None.
"""
for key in kwargs:
self.remove(key)
if isinstance(kwargs[key], list) or isinstance(kwargs[key], tuple):
for value in kwargs[key]:
self.add(key, value)
elif kwargs[key] is None:
pass
else:
self.add(key, kwargs[key])
return self
def clone(self):
"""Returns a copy of this URL builder.
Returns:
UrlBuilder: A copy of this URL builder.
"""
another = UrlBuilder(self.base_path)
another.params = [
self.Param(x.name, x.value) for x in self.params]
return another
def __str__(self):
if len(self.params) == 0:
return self.base_path
return self.base_path + "?" + "&".join([
str(x) for x in self.params])
class Param:
"""A query parameter.
Attributes:
name (str): The parameter name
value (str): The parameter value
"""
def __init__(self, name, value):
"""Constructs a new query parameter
Args:
name (str): The parameter name
value (str): The parameter value
"""
self.name = name
self.value = value
def __str__(self):
"""Returns the string representation of this query
parameter.
Returns:
str: The string representation of this query
parameter
"""
return "%s=%s" % (
urllib.parse.quote(self.name),
urllib.parse.quote(self.value))
class Pagination:
"""The pagination.
Args:
request (HttpRequest): The request.
items (list): All the items.
is_reversed (bool): Whether we should display the last page first.
Raises:
PaginationException: With invalid pagination parameters
Attributes:
current_url (UrlBuilder): The current request URL.
is_reversed (bool): Whether we should display the last page first.
page_size (int): The page size.
total_pages (int): The total number of pages available.
is_paged (bool): Whether there are more than one page.
page_no (int): The current page number.
items (list[Model]): The items in the current page.
"""
DEFAULT_PAGE_SIZE = 10
def __init__(self, request, items, is_reversed=False):
self.current_url = UrlBuilder(request.get_full_path())
self.is_reversed = is_reversed
self.page_size = self.DEFAULT_PAGE_SIZE
self.total_pages = None
self.is_paged = None
self.page_no = 1
self.items = []
# The page size
try:
self.page_size = int(request.GET["page-size"])
if self.page_size == self.DEFAULT_PAGE_SIZE:
raise PaginationException(self.current_url.remove("page-size"))
if self.page_size < 1:
raise PaginationException(self.current_url.remove("page-size"))
except KeyError:
self.page_size = self.DEFAULT_PAGE_SIZE
except ValueError:
raise PaginationException(self.current_url.remove("page-size"))
self.total_pages = int(
(len(items) - 1) / self.page_size) + 1
default_page_no = 1 if not is_reversed else self.total_pages
self.is_paged = self.total_pages > 1
# The page number
try:
self.page_no = int(request.GET["page"])
if not self.is_paged:
raise PaginationException(self.current_url.remove("page"))
if self.page_no == default_page_no:
raise PaginationException(self.current_url.remove("page"))
if self.page_no < 1:
raise PaginationException(self.current_url.remove("page"))
if self.page_no > self.total_pages:
raise PaginationException(self.current_url.remove("page"))
except KeyError:
self.page_no = default_page_no
except ValueError:
raise PaginationException(self.current_url.remove("page"))
if not self.is_paged:
self.page_no = 1
self.items = items
return
start_no = self.page_size * (self.page_no - 1)
self.items = items[start_no:start_no + self.page_size]
def links(self):
"""Returns the navigation links of the pagination bar.
Returns:
list[Link]: The navigation links of the pagination bar.
"""
base_url = self.current_url.clone().remove("page").remove("s")
links = []
# The previous page
link = self.Link()
link.title = pgettext("Pagination|", "Previous")
if self.page_no > 1:
if self.page_no - 1 == 1:
if not self.is_reversed:
link.url = str(base_url)
else:
link.url = str(base_url.clone().add(
"page", "1"))
else:
link.url = str(base_url.clone().add(
"page", str(self.page_no - 1)))
link.is_small_screen = True
links.append(link)
# The first page
link = self.Link()
link.title = "1"
if not self.is_reversed:
link.url = str(base_url)
else:
link.url = str(base_url.clone().add(
"page", "1"))
if self.page_no == 1:
link.is_active = True
links.append(link)
# The previous ellipsis
if self.page_no > 4:
link = self.Link()
if self.page_no > 5:
link.title = pgettext("Pagination|", "...")
else:
link.title = "2"
link.url = str(base_url.clone().add(
"page", "2"))
links.append(link)
# The nearby pages
for no in range(self.page_no - 2, self.page_no + 3):
if no <= 1 or no >= self.total_pages:
continue
link = self.Link()
link.title = str(no)
link.url = str(base_url.clone().add(
"page", str(no)))
if no == self.page_no:
link.is_active = True
links.append(link)
# The next ellipsis
if self.page_no + 3 < self.total_pages:
link = self.Link()
if self.page_no + 4 < self.total_pages:
link.title = pgettext("Pagination|", "...")
else:
link.title = str(self.total_pages - 1)
link.url = str(base_url.clone().add(
"page", str(self.total_pages - 1)))
links.append(link)
# The last page
link = self.Link()
link.title = str(self.total_pages)
if self.is_reversed:
link.url = str(base_url)
else:
link.url = str(base_url.clone().add(
"page", str(self.total_pages)))
if self.page_no == self.total_pages:
link.is_active = True
links.append(link)
# The next page
link = self.Link()
link.title = pgettext("Pagination|", "Next")
if self.page_no < self.total_pages:
if self.page_no + 1 == self.total_pages:
if self.is_reversed:
link.url = str(base_url)
else:
link.url = str(base_url.clone().add(
"page", str(self.total_pages)))
else:
link.url = str(base_url.clone().add(
"page", str(self.page_no + 1)))
link.is_small_screen = True
links.append(link)
return links
class Link:
"""A navigation link in the pagination bar.
Attributes:
url (str): The link URL, or for a non-link slot.
title (str): The title of the link.
is_active (bool): Whether this link is currently active.
is_small_screen (bool): Whether this link is for small
screens
"""
def __int__(self):
self.url = None
self.title = None
self.is_active = False
self.is_small_screen = False
def page_size_options(self):
"""Returns the page size options.
Returns:
list[PageSizeOption]: The page size options.
"""
base_url = self.current_url.remove("page").remove("page-size")
return [self.PageSizeOption(x, self._page_size_url(base_url, x))
for x in [10, 100, 200]]
@staticmethod
def _page_size_url(base_url, size):
"""Returns the URL for a new page size.
Args:
base_url (UrlBuilder): The base URL builder.
size (int): The new page size.
Returns:
str: The URL for the new page size.
"""
if size == Pagination.DEFAULT_PAGE_SIZE:
return str(base_url)
return str(base_url.clone().add("page-size", str(size)))
class PageSizeOption:
"""A page size option.
Args:
size (int): The page size.
url (str): The URL of this page size.
Attributes:
size (int): The page size.
url (str): The URL for this page size.
"""
def __init__(self, size, url):
self.size = size
self.url = url
class PaginationException(Exception):
"""The exception thrown with invalid pagination parameters.
Args:
url_builder (UrlBuilder): The canonical URL to redirect to.
Attributes:
url (str): The canonical URL to redirect to.
"""
def __init__(self, url_builder):
self.url = str(url_builder)