OpenSlides/openslides/config/api.py

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#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
openslides.config.api
~~~~~~~~~~~~~~~~~~~~~
Api for the config app.
:copyright: 20112013 by OpenSlides team, see AUTHORS.
:license: GNU GPL, see LICENSE for more details.
"""
from .models import ConfigStore
from .exceptions import ConfigError, ConfigNotFound
from .signals import config_signal
class ConfigHandler(object):
"""
An simple object class to wrap the config variables. It is a container
object. To get a config variable use x = config[...], to set it use
config[...] = x.
"""
def __getitem__(self, key):
try:
return self._cache[key]
except KeyError:
raise ConfigNotFound('The config variable %s was not found.' % key)
except AttributeError:
self.setup_cache()
return self[key]
def __setitem__(self, key, value):
# Save the new value to the database
updated_rows = ConfigStore.objects.filter(key=key).update(value=value)
if not updated_rows:
ConfigStore.objects.create(key=key, value=value)
# Update cache
try:
self._cache[key] = value
except AttributeError:
# This happens, when a config-var is set, before __getitem__ was
# called. In this case nothing should happen.
pass
# Call on_change callback
for receiver, config_page in config_signal.send(sender='set_value'):
for config_variable in config_page.variables:
if config_variable.name == key and config_variable.on_change:
config_variable.on_change()
break
def get_default(self, key):
"""
Returns the default value for 'key'.
"""
for receiver, config_page in config_signal.send(sender='get_default'):
for config_variable in config_page.variables:
if config_variable.name == key:
return config_variable.default_value
raise ConfigNotFound('The config variable %s was not found.' % key)
def setup_cache(self):
"""
Loads all config variables from the database and by sending a
signal to get the default into the cache.
"""
self._cache = {}
for receiver, config_page in config_signal.send(sender='setup_cache'):
for config_variable in config_page.variables:
if config_variable.name in self._cache:
raise ConfigError('Too many values for config variable %s found.' % config_variable.name)
self._cache[config_variable.name] = config_variable.default_value
for config_object in ConfigStore.objects.all():
self._cache[config_object.key] = config_object.value
def __contains__(self, key):
try:
config[key]
except ConfigNotFound:
return False
else:
return True
config = ConfigHandler()
"""
Final entry point to get an set config variables. To get a config variable
use x = config[...], to set it use config[...] = x.
"""
class ConfigBasePage(object):
"""
An abstract base class for simple and grouped config pages. The
attributes title and url are required. The attribute weight is used
for the order of the links in the submenu of the views. The attribute
extra_context can be used to insert extra css and js files into the
template.
"""
def __init__(self, title, url, required_permission=None, weight=0, extra_context={}):
self.title = title
self.url = url
self.required_permission = required_permission
self.weight = weight
self.extra_context = extra_context
def is_shown(self):
"""
Returns True if at least one variable of the page has a form field.
"""
for variable in self.variables:
if variable.form_field is not None:
return True
else:
return False
class ConfigGroupedPage(ConfigBasePage):
"""
A simple object class for a grouped config page. Developers have to
set the groups attribute (tuple). The config variables are available
via the variables attribute. The page is shown as view in the config
tab, if there is at least one variable with a form field.
"""
def __init__(self, groups, **kwargs):
self.groups = groups
super(ConfigGroupedPage, self).__init__(**kwargs)
@property
def variables(self):
for group in self.groups:
for variable in group.variables:
yield variable
class ConfigPage(ConfigBasePage):
"""
A simple object class for a ungrouped config page. Developers have
to set the variables (tuple) directly. The page is shown as view in
the config tab, if there is at least one variable with a form field.
"""
def __init__(self, variables, **kwargs):
self.variables = variables
super(ConfigPage, self).__init__(**kwargs)
class ConfigGroup(object):
"""
A simple object class representing a group of variables (tuple) with
a special title.
"""
def __init__(self, title, variables):
self.title = title
self.variables = variables
def get_field_names(self):
return [variable.name for variable in self.variables if variable.form_field is not None]
class ConfigVariable(object):
"""
A simple object class to wrap new config variables. The keyword
arguments 'name' and 'default_value' are required. The keyword
argument 'form_field' has to be set, if the variable should appear
on the ConfigView. The argument 'on_change' can get a callback
which is called every time, the variable is changed.
"""
def __init__(self, name, default_value, form_field=None, on_change=None):
self.name = name
self.default_value = default_value
self.form_field = form_field
self.on_change = on_change